Draft framework and model for refactoring composite actions

.github/workflows/build.yml

@@ -1,7 +1,6 @@
 name: Runner CI
 
 on:
-  workflow_dispatch:
   push:
     branches:
     - master

docs/adrs/0549-composite-run-steps.md

@@ -1,275 +0,0 @@
-# ADR 054x: Composite Run Steps
-
-**Date**: 2020-06-17
-
-**Status**: Proposed
-
-**Relevant PR**: https://github.com/actions/runner/pull/549
-
-## Context
-
-Customers want to be able to compose actions from actions (ex: https://github.com/actions/runner/issues/438)
-
-An important step towards meeting this goal is to build in functionality for actions where users can simply execute any number of steps. 
-
-## Guiding Principles
-
-We don't want the workflow author to need to know how the internal workings of the action work. Users shouldn't know the internal workings of the composite action (for example, `default.shell` and `default.workingDir` should not be inherited from the workflow file to the action file). When deciding how to design certain parts of composite run steps, we want to think one logical step from the consumer.
-
-A composite action is treated as **one** individual job step (aka encapsulation).
-
-
-## Decision
-
-**In this ADR, we only support running multiple run steps in an Action.** In doing so, we build in support for mapping and flowing the inputs, outputs, and env variables (ex: All nested steps should have access to its parents' input variables and nested steps can overwrite the input variables).
-
-## Steps
-
-Example `workflow.yml`
-
-```yaml
-jobs:
-  build:
-    runs-on: self-hosted
-    steps:
-    - id: step1
-      uses: actions/setup-python@v1
-    - id: step2
-      uses: actions/setup-node@v2
-    - uses: actions/checkout@v2
-    - uses: user/composite@v1
-    - name: workflow step 1
-      run: echo hello world 3
-    - name: workflow step 2
-      run: echo hello world 4
-```
-
-Example `user/composite/action.yml`
-
-```yaml
-runs:
-  using: "composite"
-  steps:
-    - run: pip install -r requirements.txt
-    - run: npm install
-```
-
-Example Output
-
-```yaml
-[npm installation output]
-[pip requirements output]
-echo hello world 3
-echo hello world 4
-```
-
-We add a token called "composite" which allows our Runner code to process composite actions. By invoking "using: composite", our Runner code then processes the "steps" attribute, converts this template code to a list of steps, and finally runs each run step sequentially. If any step fails and there are no `if` conditions defined, the whole composite action job fails. 
-
-## Inputs
-
-Example `workflow.yml`:
-
-```yaml
-steps: 
-  - id: foo
-    uses: user/composite@v1
-    with:
-      your_name: "Octocat"
-```
-
-Example `user/composite/action.yml`:
-
-```yaml
-inputs:
-  your_name:
-    description: 'Your name'
-    default: 'Ethan'
-runs:
-  using: "composite"
-  steps: 
-    - run: echo hello ${{ inputs.your_name }}
-```
-
-Example Output:
-
-```
-hello Octocat
-```
-
-Each input variable in the composite action is only viewable in its own scope.
-
-## Outputs
-
-Example `workflow.yml`:
-
-```yaml
-...
-steps: 
-  - id: foo
-    uses: user/composite@v1
-  - run: echo random-number ${{ steps.foo.outputs.random-number }} 
-```
-
-Example `user/composite/action.yml`:
-
-```yaml
-outputs:
-  random-number: 
-    description: "Random number"
-    value: ${{ steps.random-number-generator.outputs.random-id }}
-runs:
-  using: "composite"
-  steps: 
-    - id: random-number-generator
-      run: echo "::set-output name=random-number::$(echo $RANDOM)"
-```
-
-Example Output:
-
-```
-::set-output name=my-output::43243
-random-number 43243
-```
-
-Each of the output variables from the composite action is viewable from the workflow file that uses the composite action. In other words, every child action output(s) is viewable only by its parent using dot notation (ex `steps.foo.outputs.random-number`).
-
-Moreover, the output ids are only accessible within the scope where it was defined. Note that in the example above, in our `workflow.yml` file, it should not have access to output id (i.e. `random-id`). The reason why we are doing this is because we don't want to require the workflow author to know the internal workings of the composite action.
-
-## Context
-
-Similar to the workflow file, the composite action has access to the [same context objects](https://help.github.com/en/actions/reference/context-and-expression-syntax-for-github-actions#contexts) (ex: `github`, `env`, `strategy`). 
-
-## Environment
-
-In the Composite Action, you'll only be able to use `::set-env::` to set environment variables just like you could with other actions.
-
-## Secrets
-
-**Note** : This feature will be focused on in a future ADR.
-
-We'll pass the secrets from the composite action's parents (ex: the workflow file) to the composite action. Secrets can be created in the composite action with the secrets context. In the actions yaml, we'll automatically mask the secret. 
-
-
-## If Condition
-
-Example `workflow.yml`:
-
-```yaml
-steps:
-  - run: exit 1
-  - uses: user/composite@v1  # <--- this will run, as it's marked as always runing
-    if: always()
-```
-
-Example `user/composite/action.yml`:
-
-```yaml
-runs:
-  using: "composite"
-  steps:
-    - run: echo "just succeeding"
-    - run: echo "I will run, as my current scope is succeeding"
-      if: success()
-    - run: exit 1
-    - run: echo "I will not run, as my current scope is now failing"
-```
-
-See the paragraph below for a rudimentary approach (thank you to @cybojenix for the idea, example, and explanation for this approach):
-
-The `if` statement in the parent (in the example above, this is the `workflow.yml`) shows whether or not we should run the composite action. So, our composite action will run since the `if` condition for running the composite action is `always()`.
-
-**Note that the if condition on the parent does not propogate to the rest of its children though.**
-
-In the child action (in this example, this is the `action.yml`), it starts with a clean slate (in other words, no imposing if conditions). Similar to the logic in the paragraph above, `echo "I will run, as my current scope is succeeding"` will run since the `if` condition checks if the previous steps **within this composite action** has not failed. `run: echo "I will not run, as my current scope is now failing"` will not run since the previous step resulted in an error and by default, the if expression is set to `success()` if the if condition is not set for a step.
-
-
-What if a step has `cancelled()`? We do the opposite of our approach above if `cancelled()` is used for any of our composite run steps. We will cancel any step that has this condition if the workflow is cancelled at all.
-    
-## Timeout-minutes
-
-Example `workflow.yml`:
-
-```yaml
-steps: 
-  - id: bar
-    uses: user/test@v1
-    timeout-minutes: 50
-```
-
-Example `user/composite/action.yml`:
-
-```yaml
-runs:
-  using: "composite"
-  steps: 
-    - id: foo1
-      run: echo test 1
-      timeout-minutes: 10
-    - id: foo2
-      run: echo test 2
-    - id: foo3
-      run: echo test 3
-      timeout-minutes: 10
-```
-
-A composite action in its entirety is a job. You can set both timeout-minutes for the whole composite action or its steps as long as the the sum of the `timeout-minutes` for each composite action step that has the attribute `timeout-minutes` is less than or equals to `timeout-minutes` for the composite action. There is no default timeout-minutes for each composite action step. 
-
-If the time taken for any of the steps in combination or individually exceed the whole composite action `timeout-minutes` attribute, the whole job will fail (1). If an individual step exceeds its own `timeout-minutes` attribute but the total time that has been used including this step is below the overall composite action `timeout-minutes`, the individual step will fail but the rest of the steps will run based on their own `timeout-minutes` attribute (they will still abide by condition (1) though).
-
-For reference, in the example above, if the composite step `foo1` takes 11 minutes to run, that step will fail but the rest of the steps, `foo1` and `foo2`, will proceed as long as their total runtime with the previous failed `foo1` action is less than the composite action's `timeout-minutes` (50 minutes). If the composite step `foo2` takes 51 minutes to run, it will cause the whole composite action job to fail. I
-
-The rationale behind this is that users can configure their steps with the `if` condition to conditionally set how steps rely on each other. Due to the additional capabilities that are offered with combining `timeout-minutes` and/or `if`, we wanted the `timeout-minutes` condition to be as dumb as possible and not effect other steps. 
-
-[Usage limits still apply](https://help.github.com/en/actions/reference/workflow-syntax-for-github-actions?query=if%28%29#usage-limits)
-
-
-## Continue-on-error
-
-Example `workflow.yml`:
-
-```yaml
-steps: 
-  - run: exit 1
-  - id: bar
-    uses: user/test@v1
-    continue-on-error: false
-  - id: foo
-    run: echo "Hello World" <------- This step will not run
-```
-
-Example `user/composite/action.yml`:
-
-```yaml
-runs:
-  using: "composite"
-  steps: 
-    - run: exit 1
-      continue-on-error: true
-    - run: echo "Hello World 2" <----- This step will run
-```
-
-If any of the steps fail in the composite action and the `continue-on-error` is set to `false` for the whole composite action step in the workflow file, then the steps below it will run. On the flip side, if `continue-on-error` is set to `true` for the whole composite action step in the workflow file, the next job step will run.
-
-For the composite action steps, it follows the same logic as above. In this example, `"Hello World 2"` will be outputted because the previous step has `continue-on-error` set to `true` although that previous step errored. 
-
-## Defaults
-
-The composite action author will be required to set the `shell` and `workingDir` of the composite action. Moreover, the composite action author will be able to explicitly set the shell for each composite run step. The workflow author will not have the ability to change these attributes. 
-
-## Visualizing Composite Action in the GitHub Actions UI
-We want all the composite action's steps to be condensed into the original composite action node. 
-
-Here is a visual represenation of the [first example](#Steps)
-
-```yaml
-| composite_action_node |
-    | echo hello world 1 | 
-    | echo hello world 2 |
-| echo hello world 3 | 
-| echo hello world 4 |
-
-```
-
-
-## Conclusion
-This ADR lays the framework for eventually supporting nested Composite Actions within Composite Actions. This ADR allows for users to run multiple run steps within a GitHub Composite Action with the support of inputs, outputs, environment, and context for use in any steps as well as the if, timeout-minutes, and the continue-on-error attributes for each Composite Action step. 

src/Misc/externals.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 PACKAGERUNTIME=$1
 PRECACHE=$2
 

src/Misc/layoutbin/darwin.svc.sh.template

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 
 SVC_NAME="{{SvcNameVar}}"
 SVC_NAME=${SVC_NAME// /_}

src/Misc/layoutbin/installdependencies.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 
 user_id=`id -u`
 

src/Misc/layoutbin/runsvc.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 
 # convert SIGTERM signal to SIGINT
 # for more info on how to propagate SIGTERM to a child process see: http://veithen.github.io/2014/11/16/sigterm-propagation.html

src/Misc/layoutbin/systemd.svc.sh.template

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 
 SVC_NAME="{{SvcNameVar}}"
 SVC_NAME=${SVC_NAME// /_}

src/Misc/layoutbin/update.sh.template

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 
 # runner will replace key words in the template and generate a batch script to run.
 # Keywords: 

src/Misc/layoutroot/config.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 
 user_id=`id -u`
 

src/Misc/layoutroot/env.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 
 varCheckList=(
     'LANG' 

src/Misc/layoutroot/run.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 
 # Validate not sudo
 user_id=`id -u`

src/Runner.Worker/ActionManager.cs

@@ -398,10 +398,8 @@ namespace GitHub.Runner.Worker
                     else if (definition.Data.Execution.ExecutionType == ActionExecutionType.Composite && !string.IsNullOrEmpty(Environment.GetEnvironmentVariable("TESTING_COMPOSITE_ACTIONS_ALPHA")))
                     {
                         var compositeAction = definition.Data.Execution as CompositeActionExecutionData;
-                        Trace.Info($"Load {compositeAction.Steps?.Count ?? 0} action steps.");
-                        Trace.Verbose($"Details: {StringUtil.ConvertToJson(compositeAction?.Steps)}");
-                        Trace.Info($"Load: {compositeAction.Outputs?.Count ?? 0} number of outputs");
-                        Trace.Info($"Details: {StringUtil.ConvertToJson(compositeAction?.Outputs)}");
+                        Trace.Info($"Load {compositeAction.Steps.Count} action steps.");
+                        Trace.Verbose($"Details: {StringUtil.ConvertToJson(compositeAction.Steps)}");
                     }
                     else
                     {
@@ -1224,7 +1222,6 @@ namespace GitHub.Runner.Worker
         public override bool HasPre => false;
         public override bool HasPost => false;
         public List<Pipelines.ActionStep> Steps { get; set; }
-        public MappingToken Outputs { get; set; }
     }
 
     public abstract class ActionExecutionData

src/Runner.Worker/ActionManifestManager.cs

@@ -23,15 +23,11 @@ namespace GitHub.Runner.Worker
     {
         ActionDefinitionData Load(IExecutionContext executionContext, string manifestFile);
 
-        DictionaryContextData EvaluateCompositeOutputs(IExecutionContext executionContext, TemplateToken token, IDictionary<string, PipelineContextData> extraExpressionValues);
-
         List<string> EvaluateContainerArguments(IExecutionContext executionContext, SequenceToken token, IDictionary<string, PipelineContextData> extraExpressionValues);
 
         Dictionary<string, string> EvaluateContainerEnvironment(IExecutionContext executionContext, MappingToken token, IDictionary<string, PipelineContextData> extraExpressionValues);
 
         string EvaluateDefaultInput(IExecutionContext executionContext, string inputName, TemplateToken token);
-
-        void SetAllCompositeOutputs(IExecutionContext parentExecutionContext, DictionaryContextData actionOutputs);
     }
 
     public sealed class ActionManifestManager : RunnerService, IActionManifestManager
@@ -93,9 +89,6 @@ namespace GitHub.Runner.Worker
                 }
 
                 var actionMapping = token.AssertMapping("action manifest root");
-                var actionOutputs = default(MappingToken);
-                var actionRunValueToken = default(TemplateToken);
-
                 foreach (var actionPair in actionMapping)
                 {
                     var propertyName = actionPair.Key.AssertString($"action.yml property key");
@@ -106,15 +99,6 @@ namespace GitHub.Runner.Worker
                             actionDefinition.Name = actionPair.Value.AssertString("name").Value;
                             break;
 
-                        case "outputs":
-                            if (!string.IsNullOrEmpty(Environment.GetEnvironmentVariable("TESTING_COMPOSITE_ACTIONS_ALPHA")))
-                            {
-                                actionOutputs = actionPair.Value.AssertMapping("outputs");
-                                break;
-                            }
-                            Trace.Info($"Ignore action property outputs. Outputs for a whole action is not supported yet.");
-                            break;
-
                         case "description":
                             actionDefinition.Description = actionPair.Value.AssertString("description").Value;
                             break;
@@ -124,21 +108,13 @@ namespace GitHub.Runner.Worker
                             break;
 
                         case "runs":
-                            // Defer runs token evaluation to after for loop to ensure that order of outputs doesn't matter.
-                            actionRunValueToken = actionPair.Value;
+                            actionDefinition.Execution = ConvertRuns(executionContext, templateContext, actionPair.Value);
                             break;
-
                         default:
                             Trace.Info($"Ignore action property {propertyName}.");
                             break;
                     }
                 }
-
-                // Evaluate Runs Last
-                if (actionRunValueToken != null)
-                {
-                    actionDefinition.Execution = ConvertRuns(executionContext, templateContext, actionRunValueToken, actionOutputs);
-                }
             }
             catch (Exception ex)
             {
@@ -170,61 +146,6 @@ namespace GitHub.Runner.Worker
             return actionDefinition;
         }
 
-        public void SetAllCompositeOutputs(
-            IExecutionContext parentExecutionContext,
-            DictionaryContextData actionOutputs)
-        {
-            // Each pair is structured like this
-            // We ignore "description" for now
-            // {
-            //   "the-output-name": {
-            //     "description": "",
-            //     "value": "the value"
-            //   },
-            //   ...
-            // }
-            foreach (var pair in actionOutputs)
-            {
-                var outputsName = pair.Key;
-                var outputsAttributes = pair.Value as DictionaryContextData;
-                outputsAttributes.TryGetValue("value", out var val);
-                var outputsValue = val as StringContextData;
-
-                // Set output in the whole composite scope. 
-                if (!String.IsNullOrEmpty(outputsName) && !String.IsNullOrEmpty(outputsValue))
-                {
-                    parentExecutionContext.SetOutput(outputsName, outputsValue, out _);
-                }
-            }
-        }
-
-        public DictionaryContextData EvaluateCompositeOutputs(
-            IExecutionContext executionContext,
-            TemplateToken token,
-            IDictionary<string, PipelineContextData> extraExpressionValues)
-        {
-            var result = default(DictionaryContextData);
-
-            if (token != null)
-            {
-                var context = CreateContext(executionContext, extraExpressionValues);
-                try
-                {
-                    token = TemplateEvaluator.Evaluate(context, "outputs", token, 0, null, omitHeader: true);
-                    context.Errors.Check();
-                    result = token.ToContextData().AssertDictionary("composite outputs");
-                }
-                catch (Exception ex) when (!(ex is TemplateValidationException))
-                {
-                    context.Errors.Add(ex);
-                }
-
-                context.Errors.Check();
-            }
-
-            return result ?? new DictionaryContextData();
-        }
-
         public List<string> EvaluateContainerArguments(
             IExecutionContext executionContext,
             SequenceToken token,
@@ -388,8 +309,7 @@ namespace GitHub.Runner.Worker
         private ActionExecutionData ConvertRuns(
             IExecutionContext executionContext,
             TemplateContext context,
-            TemplateToken inputsToken,
-            MappingToken outputs = null)
+            TemplateToken inputsToken)
         {
             var runsMapping = inputsToken.AssertMapping("runs");
             var usingToken = default(StringToken);
@@ -405,7 +325,7 @@ namespace GitHub.Runner.Worker
             var postToken = default(StringToken);
             var postEntrypointToken = default(StringToken);
             var postIfToken = default(StringToken);
-            var stepsLoaded = default(List<Pipelines.ActionStep>);
+            var stepsLoaded = default(List<Pipelines.Step>);
 
             foreach (var run in runsMapping)
             {
@@ -456,6 +376,7 @@ namespace GitHub.Runner.Worker
                         {
                             var steps = run.Value.AssertSequence("steps");
                             var evaluator = executionContext.ToPipelineTemplateEvaluator();
+                            // TODO: Change this so that we process each type of step
                             stepsLoaded = evaluator.LoadCompositeSteps(steps);
                             break;
                         }
@@ -519,7 +440,6 @@ namespace GitHub.Runner.Worker
                         return new CompositeActionExecutionData()
                         {
                             Steps = stepsLoaded,
-                            Outputs = outputs
                         };
                     }
                 }

src/Runner.Worker/ExecutionContext.cs

@@ -6,7 +6,6 @@ using System.Globalization;
 using System.IO;
 using System.Linq;
 using System.Text;
-using System.Text.RegularExpressions;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Web;
@@ -53,6 +52,7 @@ namespace GitHub.Runner.Worker
         IDictionary<String, IDictionary<String, String>> JobDefaults { get; }
         Dictionary<string, VariableValue> JobOutputs { get; }
         IDictionary<String, String> EnvironmentVariables { get; }
+        IDictionary<String, ContextScope> Scopes { get; }
         IList<String> FileTable { get; }
         StepsContext StepsContext { get; }
         DictionaryContextData ExpressionValues { get; }
@@ -70,12 +70,10 @@ namespace GitHub.Runner.Worker
 
         bool EchoOnActionCommand { get; set; }
 
-        IExecutionContext FinalizeContext { get; set; }
-
         // Initialize
         void InitializeJob(Pipelines.AgentJobRequestMessage message, CancellationToken token);
         void CancelToken();
-        IExecutionContext CreateChild(Guid recordId, string displayName, string refName, string scopeName, string contextName, Dictionary<string, string> intraActionState = null, int? recordOrder = null, IPagingLogger logger = null);
+        IExecutionContext CreateChild(Guid recordId, string displayName, string refName, string scopeName, string contextName, Dictionary<string, string> intraActionState = null, int? recordOrder = null);
 
         // logging
         bool WriteDebug { get; }
@@ -107,7 +105,7 @@ namespace GitHub.Runner.Worker
         // others
         void ForceTaskComplete();
         void RegisterPostJobStep(IStep step);
-        IStep RegisterNestedStep(IActionRunner step, DictionaryContextData inputsData, int location, Dictionary<string, string> envData, bool cleanUp = false);
+        void RegisterNestedStep(IStep step, DictionaryContextData inputsData, int location, Dictionary<string, string> envData);
     }
 
     public sealed class ExecutionContext : RunnerService, IExecutionContext
@@ -122,9 +120,6 @@ namespace GitHub.Runner.Worker
 
         private event OnMatcherChanged _onMatcherChanged;
 
-        // Regex used for checking if ScopeName meets the condition that shows that its id is null.
-        private readonly static Regex _generatedContextNamePattern = new Regex("^__[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}$", RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.IgnoreCase);
-
         private IssueMatcherConfig[] _matchers;
 
         private IPagingLogger _logger;
@@ -154,6 +149,7 @@ namespace GitHub.Runner.Worker
         public IDictionary<String, IDictionary<String, String>> JobDefaults { get; private set; }
         public Dictionary<string, VariableValue> JobOutputs { get; private set; }
         public IDictionary<String, String> EnvironmentVariables { get; private set; }
+        public IDictionary<String, ContextScope> Scopes { get; private set; }
         public IList<String> FileTable { get; private set; }
         public StepsContext StepsContext { get; private set; }
         public DictionaryContextData ExpressionValues { get; } = new DictionaryContextData();
@@ -174,8 +170,6 @@ namespace GitHub.Runner.Worker
 
         public bool EchoOnActionCommand { get; set; }
 
-        public IExecutionContext FinalizeContext { get; set; }
-
         public TaskResult? Result
         {
             get
@@ -276,34 +270,17 @@ namespace GitHub.Runner.Worker
         /// Helper function used in CompositeActionHandler::RunAsync to
         /// add a child node, aka a step, to the current job to the Root.JobSteps based on the location. 
         /// </summary>
-        public IStep RegisterNestedStep(
-            IActionRunner step,
-            DictionaryContextData inputsData,
-            int location,
-            Dictionary<string, string> envData,
-            bool cleanUp = false)
+        public void RegisterNestedStep(IStep step, DictionaryContextData inputsData, int location, Dictionary<string, string> envData)
         {
-            // If the context name is empty and the scope name is empty, we would generate a unique scope name for this child in the following format:
-            // "__<GUID>"
-            var safeContextName = !string.IsNullOrEmpty(ContextName) ? ContextName : $"__{Guid.NewGuid()}";
-
-            // Set Scope Name. Note, for our design, we consider each step in a composite action to have the same scope
-            // This makes it much simpler to handle their outputs at the end of the Composite Action
-            var childScopeName = !string.IsNullOrEmpty(ScopeName) ? $"{ScopeName}.{safeContextName}" : safeContextName;
-
-            var childContextName = !string.IsNullOrEmpty(step.Action.ContextName) ? step.Action.ContextName : $"__{Guid.NewGuid()}";
-
-            step.ExecutionContext = Root.CreateChild(_record.Id, step.DisplayName, _record.Id.ToString("N"), childScopeName, childContextName, logger: _logger);
-
+            // TODO: For UI purposes, look at figuring out how to condense steps in one node => maybe use the same previous GUID
+            var newGuid = Guid.NewGuid();
+            step.ExecutionContext = Root.CreateChild(newGuid, step.DisplayName, newGuid.ToString("N"), null, null);
             step.ExecutionContext.ExpressionValues["inputs"] = inputsData;
 
-            // Set Parent Attribute for Clean Up Step
-            if (cleanUp)
-            {
-                step.ExecutionContext.FinalizeContext = this;
-            }
-
             // Add the composite action environment variables to each step.
+            // If the key already exists, we override it since the composite action env variables will have higher precedence
+            // Note that for each composite action step, it's environment variables will be set in the StepRunner automatically
+            // step.ExecutionContext.SetEnvironmentVariables(envData);
 #if OS_WINDOWS
             var envContext = new DictionaryContextData();
 #else
@@ -316,11 +293,9 @@ namespace GitHub.Runner.Worker
             step.ExecutionContext.ExpressionValues["env"] = envContext;
 
             Root.JobSteps.Insert(location, step);
-
-            return step;
         }
 
-        public IExecutionContext CreateChild(Guid recordId, string displayName, string refName, string scopeName, string contextName, Dictionary<string, string> intraActionState = null, int? recordOrder = null, IPagingLogger logger = null)
+        public IExecutionContext CreateChild(Guid recordId, string displayName, string refName, string scopeName, string contextName, Dictionary<string, string> intraActionState = null, int? recordOrder = null)
         {
             Trace.Entering();
 
@@ -342,6 +317,7 @@ namespace GitHub.Runner.Worker
             }
             child.EnvironmentVariables = EnvironmentVariables;
             child.JobDefaults = JobDefaults;
+            child.Scopes = Scopes;
             child.FileTable = FileTable;
             child.StepsContext = StepsContext;
             foreach (var pair in ExpressionValues)
@@ -368,15 +344,9 @@ namespace GitHub.Runner.Worker
             {
                 child.InitializeTimelineRecord(_mainTimelineId, recordId, _record.Id, ExecutionContextType.Task, displayName, refName, ++_childTimelineRecordOrder);
             }
-            if (logger != null)
-            {
-                child._logger = logger;
-            }
-            else
-            {
-                child._logger = HostContext.CreateService<IPagingLogger>();
-                child._logger.Setup(_mainTimelineId, recordId);
-            }
+
+            child._logger = HostContext.CreateService<IPagingLogger>();
+            child._logger.Setup(_mainTimelineId, recordId);
 
             return child;
         }
@@ -496,8 +466,7 @@ namespace GitHub.Runner.Worker
         {
             ArgUtil.NotNullOrEmpty(name, nameof(name));
 
-            // if the ContextName follows the __GUID format which is set as the default value for ContextName if null for Composite Actions. 
-            if (String.IsNullOrEmpty(ContextName) || _generatedContextNamePattern.IsMatch(ContextName))
+            if (String.IsNullOrEmpty(ContextName))
             {
                 reference = null;
                 return;
@@ -664,6 +633,16 @@ namespace GitHub.Runner.Worker
             // Steps context (StepsRunner manages adding the scoped steps context)
             StepsContext = new StepsContext();
 
+            // Scopes
+            Scopes = new Dictionary<String, ContextScope>(StringComparer.OrdinalIgnoreCase);
+            if (message.Scopes?.Count > 0)
+            {
+                foreach (var scope in message.Scopes)
+                {
+                    Scopes[scope.Name] = scope;
+                }
+            }
+
             // File table
             FileTable = new List<String>(message.FileTable ?? new string[0]);
 

src/Runner.Worker/Handlers/CompositeActionHandler.cs

@@ -35,9 +35,6 @@ namespace GitHub.Runner.Worker.Handlers
 
             var tempDirectory = HostContext.GetDirectory(WellKnownDirectory.Temp);
 
-            // Resolve action steps
-            var actionSteps = Data.Steps;
-
             // Create Context Data to reuse for each composite action step
             var inputsData = new DictionaryContextData();
             foreach (var i in Inputs)
@@ -48,70 +45,97 @@ namespace GitHub.Runner.Worker.Handlers
             // Add each composite action step to the front of the queue
             int location = 0;
 
-            foreach (Pipelines.ActionStep aStep in actionSteps)
+            // Resolve action steps
+            var compositeSteps = Data.Steps;
+
+            // TODO: Assume that each step is not an actionStep
+            // How do we handle all types of steps?????
+
+            // While loop till we have reached the last layer?
+            List<Pipelines.Step> stepsToAppend = new List<Pipelines.Step>();
+
+            // First put each step in stepsToAppend
+            foreach (var step in compositeSteps)
             {
-                // Ex: 
-                // runs:
-                //      using: "composite"
-                //      steps:
-                //          - uses: example/test-composite@v2 (a)
-                //          - run echo hello world (b)
-                //          - run echo hello world 2 (c)
-                // 
-                // ethanchewy/test-composite/action.yaml
-                // runs:
-                //      using: "composite"
-                //      steps: 
-                //          - run echo hello world 3 (d)
-                //          - run echo hello world 4 (e)
-                // 
-                // Steps processed as follow:
-                // | a |
-                // | a | => | d |
-                // (Run step d)
-                // | a | 
-                // | a | => | e |
-                // (Run step e)
-                // | a | 
-                // (Run step a)
-                // | b | 
-                // (Run step b)
-                // | c |
-                // (Run step c)
-                // Done.
-
-                var actionRunner = HostContext.CreateService<IActionRunner>();
-                actionRunner.Action = aStep;
-                actionRunner.Stage = stage;
-                actionRunner.Condition = aStep.Condition;
-
-                var step = ExecutionContext.RegisterNestedStep(actionRunner, inputsData, location, Environment);
-
-                InitializeScope(step);
-
-                location++;
+                stepsToAppend.Append(step);
             }
 
-            // Create a step that handles all the composite action steps' outputs
-            Pipelines.ActionStep cleanOutputsStep = new Pipelines.ActionStep();
-            cleanOutputsStep.ContextName = ExecutionContext.ContextName;
-            // Use the same reference type as our composite steps.
-            cleanOutputsStep.Reference = Action;
+            // We go through each step and push to the top of the stack its children. 
+            // That way, we go through each steps, steps of steps in order
+            // This is an ITERATIVE approach. While a recursive approach may be more elegant, 
+            // that would use a lot more memory in the call stack.
+            // Ex: 
+            // Let's say we have 4 composite steps with the first step that has 3 children
+            // A (composite step)=> a1, a2, a3
+            // B (non composite)
+            // C (non composite)
+            // D (non composite)
+            // It would be executed in this order => a1, a2, a3, A (steps within A), B, C, D
+            while (stepsToAppend != null)
+            {
+                var currentStep = stepsToAppend[0];
 
-            var actionRunner2 = HostContext.CreateService<IActionRunner>();
-            actionRunner2.Action = cleanOutputsStep;
-            actionRunner2.Stage = ActionRunStage.Main;
-            actionRunner2.Condition = "always()";
-            ExecutionContext.RegisterNestedStep(actionRunner2, inputsData, location, Environment, true);
+                // TODO: Create another StepsContext?
+                // In the original StepsRunner, we could lock the thread and only proceed after we finish processing these steps
+                // Then, we invoke the CompositeStepsRunner class?
+
+                // TODO: We have to create another Execution Context for Composite Actions
+                // See below
+
+                // TODO: Append to StepsRunner
+                // by invoking a RegisterNestedStep on the Composite Action Exeuction Context for Composite Action Steps
+
+
+            }
+
+            // foreach (Pipelines.Step aStep in actionSteps)
+            // {
+            //     // Ex: 
+            //     // runs:
+            //     //      using: "composite"
+            //     //      steps:
+            //     //          - uses: example/test-composite@v2 (a)
+            //     //          - run echo hello world (b)
+            //     //          - run echo hello world 2 (c)
+            //     // 
+            //     // ethanchewy/test-composite/action.yaml
+            //     // runs:
+            //     //      using: "composite"
+            //     //      steps: 
+            //     //          - run echo hello world 3 (d)
+            //     //          - run echo hello world 4 (e)
+            //     // 
+            //     // Steps processed as follow:
+            //     // | a |
+            //     // | a | => | d |
+            //     // (Run step d)
+            //     // | a | 
+            //     // | a | => | e |
+            //     // (Run step e)
+            //     // | a | 
+            //     // (Run step a)
+            //     // | b | 
+            //     // (Run step b)
+            //     // | c |
+            //     // (Run step c)
+            //     // Done.
+
+            //     // TODO: how are we going to order each step?
+            //     // How is this going to look in the UI (will we have a bunch of nesting)
+            //     // ^ We need to focus on how we are going to get the steps to run in the right order. 
+
+            //     var actionRunner = HostContext.CreateService<IActionRunner>();
+            //     actionRunner.Action = aStep;
+            //     actionRunner.Stage = stage;
+            //     actionRunner.Condition = aStep.Condition;
+            //     actionRunner.DisplayName = aStep.DisplayName;
+
+            //     ExecutionContext.RegisterNestedStep(actionRunner, inputsData, location, Environment);
+            //     location++;
+            // }
 
             return Task.CompletedTask;
         }
 
-        private void InitializeScope(IStep step)
-        {
-            var stepsContext = step.ExecutionContext.StepsContext;
-            var scopeName = step.ExecutionContext.ScopeName;
-            step.ExecutionContext.ExpressionValues["steps"] = stepsContext.GetScope(scopeName);
-        }
     }
 }

src/Runner.Worker/Handlers/CompositeActionOutputHandler.cs

@@ -1,53 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using GitHub.DistributedTask.ObjectTemplating.Schema;
-using GitHub.DistributedTask.ObjectTemplating.Tokens;
-using GitHub.DistributedTask.Pipelines.ContextData;
-using GitHub.DistributedTask.WebApi;
-using GitHub.Runner.Common;
-using GitHub.Runner.Sdk;
-using Pipelines = GitHub.DistributedTask.Pipelines;
-
-namespace GitHub.Runner.Worker.Handlers
-{
-    [ServiceLocator(Default = typeof(CompositeActionOutputHandler))]
-    public interface ICompositeActionOutputHandler : IHandler
-    {
-        CompositeActionExecutionData Data { get; set; }
-    }
-
-    public sealed class CompositeActionOutputHandler : Handler, ICompositeActionOutputHandler
-    {
-        public CompositeActionExecutionData Data { get; set; }
-
-
-        public Task RunAsync(ActionRunStage stage)
-        {
-            // Evaluate the mapped outputs value
-            if (Data.Outputs != null)
-            {
-                // Evaluate the outputs in the steps context to easily retrieve the values
-                var actionManifestManager = HostContext.GetService<IActionManifestManager>();
-
-                // Format ExpressionValues to Dictionary<string, PipelineContextData>
-                var evaluateContext = new Dictionary<string, PipelineContextData>(StringComparer.OrdinalIgnoreCase);
-                foreach (var pair in ExecutionContext.ExpressionValues)
-                {
-                    evaluateContext[pair.Key] = pair.Value;
-                }
-
-                // Get the evluated composite outputs' values mapped to the outputs named
-                DictionaryContextData actionOutputs = actionManifestManager.EvaluateCompositeOutputs(ExecutionContext, Data.Outputs, evaluateContext);
-
-                // Set the outputs for the outputs object in the whole composite action
-                actionManifestManager.SetAllCompositeOutputs(ExecutionContext.FinalizeContext, actionOutputs);
-            }
-
-            return Task.CompletedTask;
-        }
-    }
-}

src/Runner.Worker/Handlers/HandlerFactory.cs

@@ -68,16 +68,8 @@ namespace GitHub.Runner.Worker.Handlers
             }
             else if (data.ExecutionType == ActionExecutionType.Composite)
             {
-                if (executionContext.FinalizeContext == null)
-                {
-                    handler = HostContext.CreateService<ICompositeActionHandler>();
-                    (handler as ICompositeActionHandler).Data = data as CompositeActionExecutionData;
-                }
-                else
-                {
-                    handler = HostContext.CreateService<ICompositeActionOutputHandler>();
-                    (handler as ICompositeActionOutputHandler).Data = data as CompositeActionExecutionData;
-                }
+                handler = HostContext.CreateService<ICompositeActionHandler>();
+                (handler as ICompositeActionHandler).Data = data as CompositeActionExecutionData;
             }
             else
             {

src/Runner.Worker/StepsRunner.cs

@@ -67,6 +67,7 @@ namespace GitHub.Runner.Worker
 
                 var step = jobContext.JobSteps[0];
                 jobContext.JobSteps.RemoveAt(0);
+                var nextStep = jobContext.JobSteps.Count > 0 ? jobContext.JobSteps[0] : null;
 
                 Trace.Info($"Processing step: DisplayName='{step.DisplayName}'");
                 ArgUtil.NotNull(step.ExecutionContext, nameof(step.ExecutionContext));
@@ -82,170 +83,171 @@ namespace GitHub.Runner.Worker
                 step.ExecutionContext.ExpressionFunctions.Add(new FunctionInfo<SuccessFunction>(PipelineTemplateConstants.Success, 0, 0));
                 step.ExecutionContext.ExpressionFunctions.Add(new FunctionInfo<HashFilesFunction>(PipelineTemplateConstants.HashFiles, 1, byte.MaxValue));
 
-                step.ExecutionContext.ExpressionValues["steps"] = step.ExecutionContext.StepsContext.GetScope(step.ExecutionContext.ScopeName);
-
-                // Populate env context for each step
-                Trace.Info("Initialize Env context for step");
+                // Initialize scope
+                if (InitializeScope(step, scopeInputs))
+                {
+                    // Populate env context for each step
+                    Trace.Info("Initialize Env context for step");
 #if OS_WINDOWS
-                var envContext = new DictionaryContextData();
+                    var envContext = new DictionaryContextData();
 #else
-                var envContext = new CaseSensitiveDictionaryContextData();
+                    var envContext = new CaseSensitiveDictionaryContextData();
 #endif
+                    // Global env
+                    foreach (var pair in step.ExecutionContext.EnvironmentVariables)
+                    {
+                        envContext[pair.Key] = new StringContextData(pair.Value ?? string.Empty);
+                    }
 
-                // Global env
-                foreach (var pair in step.ExecutionContext.EnvironmentVariables)
-                {
-                    envContext[pair.Key] = new StringContextData(pair.Value ?? string.Empty);
-                }
-
-                // Stomps over with outside step env
-                if (step.ExecutionContext.ExpressionValues.TryGetValue("env", out var envContextData))
-                {
+                    // Stomps over with outside step env
+                    if (step.ExecutionContext.ExpressionValues.TryGetValue("env", out var envContextData))
+                    {
 #if OS_WINDOWS
-                    var dict = envContextData as DictionaryContextData;
+                        var dict = envContextData as DictionaryContextData;
 #else
-                    var dict = envContextData as CaseSensitiveDictionaryContextData;
+                        var dict = envContextData as CaseSensitiveDictionaryContextData;
 #endif
-                    foreach (var pair in dict)
-                    {
-                        envContext[pair.Key] = pair.Value;
-                    }
-                }
-
-                step.ExecutionContext.ExpressionValues["env"] = envContext;
-
-                bool evaluateStepEnvFailed = false;
-                if (step is IActionRunner actionStep)
-                {
-                    // Set GITHUB_ACTION
-                    step.ExecutionContext.SetGitHubContext("action", actionStep.Action.Name);
-
-                    try
-                    {
-                        // Evaluate and merge action's env block to env context
-                        var templateEvaluator = step.ExecutionContext.ToPipelineTemplateEvaluator();
-                        var actionEnvironment = templateEvaluator.EvaluateStepEnvironment(actionStep.Action.Environment, step.ExecutionContext.ExpressionValues, step.ExecutionContext.ExpressionFunctions, VarUtil.EnvironmentVariableKeyComparer);
-                        foreach (var env in actionEnvironment)
+                        foreach (var pair in dict)
                         {
-                            envContext[env.Key] = new StringContextData(env.Value ?? string.Empty);
+                            envContext[pair.Key] = pair.Value;
                         }
                     }
-                    catch (Exception ex)
+
+                    step.ExecutionContext.ExpressionValues["env"] = envContext;
+
+                    bool evaluateStepEnvFailed = false;
+                    if (step is IActionRunner actionStep)
                     {
-                        // fail the step since there is an evaluate error.
-                        Trace.Info("Caught exception from expression for step.env");
-                        evaluateStepEnvFailed = true;
-                        step.ExecutionContext.Error(ex);
-                        CompleteStep(step, TaskResult.Failed);
-                    }
-                }
+                        // Set GITHUB_ACTION
+                        step.ExecutionContext.SetGitHubContext("action", actionStep.Action.Name);
 
-                if (!evaluateStepEnvFailed)
-                {
-                    try
-                    {
-                        // Register job cancellation call back only if job cancellation token not been fire before each step run
-                        if (!jobContext.CancellationToken.IsCancellationRequested)
+                        try
                         {
-                            // Test the condition again. The job was canceled after the condition was originally evaluated.
-                            jobCancelRegister = jobContext.CancellationToken.Register(() =>
+                            // Evaluate and merge action's env block to env context
+                            var templateEvaluator = step.ExecutionContext.ToPipelineTemplateEvaluator();
+                            var actionEnvironment = templateEvaluator.EvaluateStepEnvironment(actionStep.Action.Environment, step.ExecutionContext.ExpressionValues, step.ExecutionContext.ExpressionFunctions, VarUtil.EnvironmentVariableKeyComparer);
+                            foreach (var env in actionEnvironment)
                             {
-                                // mark job as cancelled
-                                jobContext.Result = TaskResult.Canceled;
-                                jobContext.JobContext.Status = jobContext.Result?.ToActionResult();
-
-                                step.ExecutionContext.Debug($"Re-evaluate condition on job cancellation for step: '{step.DisplayName}'.");
-                                var conditionReTestTraceWriter = new ConditionTraceWriter(Trace, null); // host tracing only
-                                var conditionReTestResult = false;
-                                if (HostContext.RunnerShutdownToken.IsCancellationRequested)
-                                {
-                                    step.ExecutionContext.Debug($"Skip Re-evaluate condition on runner shutdown.");
-                                }
-                                else
-                                {
-                                    try
-                                    {
-                                        var templateEvaluator = step.ExecutionContext.ToPipelineTemplateEvaluator(conditionReTestTraceWriter);
-                                        var condition = new BasicExpressionToken(null, null, null, step.Condition);
-                                        conditionReTestResult = templateEvaluator.EvaluateStepIf(condition, step.ExecutionContext.ExpressionValues, step.ExecutionContext.ExpressionFunctions, step.ExecutionContext.ToExpressionState());
-                                    }
-                                    catch (Exception ex)
-                                    {
-                                        // Cancel the step since we get exception while re-evaluate step condition.
-                                        Trace.Info("Caught exception from expression when re-test condition on job cancellation.");
-                                        step.ExecutionContext.Error(ex);
-                                    }
-                                }
-
-                                if (!conditionReTestResult)
-                                {
-                                    // Cancel the step.
-                                    Trace.Info("Cancel current running step.");
-                                    step.ExecutionContext.CancelToken();
-                                }
-                            });
-                        }
-                        else
-                        {
-                            if (jobContext.Result != TaskResult.Canceled)
-                            {
-                                // mark job as cancelled
-                                jobContext.Result = TaskResult.Canceled;
-                                jobContext.JobContext.Status = jobContext.Result?.ToActionResult();
+                                envContext[env.Key] = new StringContextData(env.Value ?? string.Empty);
                             }
                         }
-
-                        // Evaluate condition.
-                        step.ExecutionContext.Debug($"Evaluating condition for step: '{step.DisplayName}'");
-                        var conditionTraceWriter = new ConditionTraceWriter(Trace, step.ExecutionContext);
-                        var conditionResult = false;
-                        var conditionEvaluateError = default(Exception);
-                        if (HostContext.RunnerShutdownToken.IsCancellationRequested)
-                        {
-                            step.ExecutionContext.Debug($"Skip evaluate condition on runner shutdown.");
-                        }
-                        else
-                        {
-                            try
-                            {
-                                var templateEvaluator = step.ExecutionContext.ToPipelineTemplateEvaluator(conditionTraceWriter);
-                                var condition = new BasicExpressionToken(null, null, null, step.Condition);
-                                conditionResult = templateEvaluator.EvaluateStepIf(condition, step.ExecutionContext.ExpressionValues, step.ExecutionContext.ExpressionFunctions, step.ExecutionContext.ToExpressionState());
-                            }
-                            catch (Exception ex)
-                            {
-                                Trace.Info("Caught exception from expression.");
-                                Trace.Error(ex);
-                                conditionEvaluateError = ex;
-                            }
-                        }
-
-                        // no evaluate error but condition is false
-                        if (!conditionResult && conditionEvaluateError == null)
-                        {
-                            // Condition == false
-                            Trace.Info("Skipping step due to condition evaluation.");
-                            CompleteStep(step, TaskResult.Skipped, resultCode: conditionTraceWriter.Trace);
-                        }
-                        else if (conditionEvaluateError != null)
+                        catch (Exception ex)
                         {
                             // fail the step since there is an evaluate error.
-                            step.ExecutionContext.Error(conditionEvaluateError);
-                            CompleteStep(step, TaskResult.Failed);
-                        }
-                        else
-                        {
-                            // Run the step.
-                            await RunStepAsync(step, jobContext.CancellationToken);
-                            CompleteStep(step);
+                            Trace.Info("Caught exception from expression for step.env");
+                            evaluateStepEnvFailed = true;
+                            step.ExecutionContext.Error(ex);
+                            CompleteStep(step, nextStep, TaskResult.Failed);
                         }
                     }
-                    finally
+
+                    if (!evaluateStepEnvFailed)
                     {
-                        if (jobCancelRegister != null)
+                        try
                         {
-                            jobCancelRegister?.Dispose();
-                            jobCancelRegister = null;
+                            // Register job cancellation call back only if job cancellation token not been fire before each step run
+                            if (!jobContext.CancellationToken.IsCancellationRequested)
+                            {
+                                // Test the condition again. The job was canceled after the condition was originally evaluated.
+                                jobCancelRegister = jobContext.CancellationToken.Register(() =>
+                                {
+                                    // mark job as cancelled
+                                    jobContext.Result = TaskResult.Canceled;
+                                    jobContext.JobContext.Status = jobContext.Result?.ToActionResult();
+
+                                    step.ExecutionContext.Debug($"Re-evaluate condition on job cancellation for step: '{step.DisplayName}'.");
+                                    var conditionReTestTraceWriter = new ConditionTraceWriter(Trace, null); // host tracing only
+                                    var conditionReTestResult = false;
+                                    if (HostContext.RunnerShutdownToken.IsCancellationRequested)
+                                    {
+                                        step.ExecutionContext.Debug($"Skip Re-evaluate condition on runner shutdown.");
+                                    }
+                                    else
+                                    {
+                                        try
+                                        {
+                                            var templateEvaluator = step.ExecutionContext.ToPipelineTemplateEvaluator(conditionReTestTraceWriter);
+                                            var condition = new BasicExpressionToken(null, null, null, step.Condition);
+                                            conditionReTestResult = templateEvaluator.EvaluateStepIf(condition, step.ExecutionContext.ExpressionValues, step.ExecutionContext.ExpressionFunctions, step.ExecutionContext.ToExpressionState());
+                                        }
+                                        catch (Exception ex)
+                                        {
+                                            // Cancel the step since we get exception while re-evaluate step condition.
+                                            Trace.Info("Caught exception from expression when re-test condition on job cancellation.");
+                                            step.ExecutionContext.Error(ex);
+                                        }
+                                    }
+
+                                    if (!conditionReTestResult)
+                                    {
+                                        // Cancel the step.
+                                        Trace.Info("Cancel current running step.");
+                                        step.ExecutionContext.CancelToken();
+                                    }
+                                });
+                            }
+                            else
+                            {
+                                if (jobContext.Result != TaskResult.Canceled)
+                                {
+                                    // mark job as cancelled
+                                    jobContext.Result = TaskResult.Canceled;
+                                    jobContext.JobContext.Status = jobContext.Result?.ToActionResult();
+                                }
+                            }
+
+                            // Evaluate condition.
+                            step.ExecutionContext.Debug($"Evaluating condition for step: '{step.DisplayName}'");
+                            var conditionTraceWriter = new ConditionTraceWriter(Trace, step.ExecutionContext);
+                            var conditionResult = false;
+                            var conditionEvaluateError = default(Exception);
+                            if (HostContext.RunnerShutdownToken.IsCancellationRequested)
+                            {
+                                step.ExecutionContext.Debug($"Skip evaluate condition on runner shutdown.");
+                            }
+                            else
+                            {
+                                try
+                                {
+                                    var templateEvaluator = step.ExecutionContext.ToPipelineTemplateEvaluator(conditionTraceWriter);
+                                    var condition = new BasicExpressionToken(null, null, null, step.Condition);
+                                    conditionResult = templateEvaluator.EvaluateStepIf(condition, step.ExecutionContext.ExpressionValues, step.ExecutionContext.ExpressionFunctions, step.ExecutionContext.ToExpressionState());
+                                }
+                                catch (Exception ex)
+                                {
+                                    Trace.Info("Caught exception from expression.");
+                                    Trace.Error(ex);
+                                    conditionEvaluateError = ex;
+                                }
+                            }
+
+                            // no evaluate error but condition is false
+                            if (!conditionResult && conditionEvaluateError == null)
+                            {
+                                // Condition == false
+                                Trace.Info("Skipping step due to condition evaluation.");
+                                CompleteStep(step, nextStep, TaskResult.Skipped, resultCode: conditionTraceWriter.Trace);
+                            }
+                            else if (conditionEvaluateError != null)
+                            {
+                                // fail the step since there is an evaluate error.
+                                step.ExecutionContext.Error(conditionEvaluateError);
+                                CompleteStep(step, nextStep, TaskResult.Failed);
+                            }
+                            else
+                            {
+                                // Run the step.
+                                await RunStepAsync(step, jobContext.CancellationToken);
+                                CompleteStep(step, nextStep);
+                            }
+                        }
+                        finally
+                        {
+                            if (jobCancelRegister != null)
+                            {
+                                jobCancelRegister?.Dispose();
+                                jobCancelRegister = null;
+                            }
                         }
                     }
                 }
@@ -399,9 +401,125 @@ namespace GitHub.Runner.Worker
             step.ExecutionContext.Debug($"Finishing: {step.DisplayName}");
         }
 
-        private void CompleteStep(IStep step, TaskResult? result = null, string resultCode = null)
+        private bool InitializeScope(IStep step, Dictionary<string, PipelineContextData> scopeInputs)
         {
             var executionContext = step.ExecutionContext;
+            var stepsContext = executionContext.StepsContext;
+            if (!string.IsNullOrEmpty(executionContext.ScopeName))
+            {
+                // Gather uninitialized current and ancestor scopes
+                var scope = executionContext.Scopes[executionContext.ScopeName];
+                var scopesToInitialize = default(Stack<ContextScope>);
+                while (scope != null && !scopeInputs.ContainsKey(scope.Name))
+                {
+                    if (scopesToInitialize == null)
+                    {
+                        scopesToInitialize = new Stack<ContextScope>();
+                    }
+                    scopesToInitialize.Push(scope);
+                    scope = string.IsNullOrEmpty(scope.ParentName) ? null : executionContext.Scopes[scope.ParentName];
+                }
+
+                // Initialize current and ancestor scopes
+                while (scopesToInitialize?.Count > 0)
+                {
+                    scope = scopesToInitialize.Pop();
+                    executionContext.Debug($"Initializing scope '{scope.Name}'");
+                    executionContext.ExpressionValues["steps"] = stepsContext.GetScope(scope.ParentName);
+                    // TODO: Fix this temporary workaround for Composite Actions
+                    if (!executionContext.ExpressionValues.ContainsKey("inputs") && !string.IsNullOrEmpty(Environment.GetEnvironmentVariable("TESTING_COMPOSITE_ACTIONS_ALPHA")))
+                    {
+                        executionContext.ExpressionValues["inputs"] = !String.IsNullOrEmpty(scope.ParentName) ? scopeInputs[scope.ParentName] : null;
+                    }
+                    var templateEvaluator = executionContext.ToPipelineTemplateEvaluator();
+                    var inputs = default(DictionaryContextData);
+                    try
+                    {
+                        inputs = templateEvaluator.EvaluateStepScopeInputs(scope.Inputs, executionContext.ExpressionValues, executionContext.ExpressionFunctions);
+                    }
+                    catch (Exception ex)
+                    {
+                        Trace.Info($"Caught exception from initialize scope '{scope.Name}'");
+                        Trace.Error(ex);
+                        executionContext.Error(ex);
+                        executionContext.Complete(TaskResult.Failed);
+                        return false;
+                    }
+
+                    scopeInputs[scope.Name] = inputs;
+                }
+            }
+
+            // Setup expression values
+            var scopeName = executionContext.ScopeName;
+            executionContext.ExpressionValues["steps"] = stepsContext.GetScope(scopeName);
+            // TODO: Fix this temporary workaround for Composite Actions
+            if (!executionContext.ExpressionValues.ContainsKey("inputs") && !string.IsNullOrEmpty(Environment.GetEnvironmentVariable("TESTING_COMPOSITE_ACTIONS_ALPHA")))
+            {
+                executionContext.ExpressionValues["inputs"] = string.IsNullOrEmpty(scopeName) ? null : scopeInputs[scopeName];
+            }
+
+            return true;
+        }
+
+        private void CompleteStep(IStep step, IStep nextStep, TaskResult? result = null, string resultCode = null)
+        {
+            var executionContext = step.ExecutionContext;
+            if (!string.IsNullOrEmpty(executionContext.ScopeName))
+            {
+                // Gather current and ancestor scopes to finalize
+                var scope = executionContext.Scopes[executionContext.ScopeName];
+                var scopesToFinalize = default(Queue<ContextScope>);
+                var nextStepScopeName = nextStep?.ExecutionContext.ScopeName;
+                while (scope != null &&
+                    !string.Equals(nextStepScopeName, scope.Name, StringComparison.OrdinalIgnoreCase) &&
+                    !(nextStepScopeName ?? string.Empty).StartsWith($"{scope.Name}.", StringComparison.OrdinalIgnoreCase))
+                {
+                    if (scopesToFinalize == null)
+                    {
+                        scopesToFinalize = new Queue<ContextScope>();
+                    }
+                    scopesToFinalize.Enqueue(scope);
+                    scope = string.IsNullOrEmpty(scope.ParentName) ? null : executionContext.Scopes[scope.ParentName];
+                }
+
+                // Finalize current and ancestor scopes
+                var stepsContext = step.ExecutionContext.StepsContext;
+                while (scopesToFinalize?.Count > 0)
+                {
+                    scope = scopesToFinalize.Dequeue();
+                    executionContext.Debug($"Finalizing scope '{scope.Name}'");
+                    executionContext.ExpressionValues["steps"] = stepsContext.GetScope(scope.Name);
+                    executionContext.ExpressionValues["inputs"] = null;
+                    var templateEvaluator = executionContext.ToPipelineTemplateEvaluator();
+                    var outputs = default(DictionaryContextData);
+                    try
+                    {
+                        outputs = templateEvaluator.EvaluateStepScopeOutputs(scope.Outputs, executionContext.ExpressionValues, executionContext.ExpressionFunctions);
+                    }
+                    catch (Exception ex)
+                    {
+                        Trace.Info($"Caught exception from finalize scope '{scope.Name}'");
+                        Trace.Error(ex);
+                        executionContext.Error(ex);
+                        executionContext.Complete(TaskResult.Failed);
+                        return;
+                    }
+
+                    if (outputs?.Count > 0)
+                    {
+                        var parentScopeName = scope.ParentName;
+                        var contextName = scope.ContextName;
+                        foreach (var pair in outputs)
+                        {
+                            var outputName = pair.Key;
+                            var outputValue = pair.Value.ToString();
+                            stepsContext.SetOutput(parentScopeName, contextName, outputName, outputValue, out var reference);
+                            executionContext.Debug($"{reference}='{outputValue}'");
+                        }
+                    }
+                }
+            }
 
             executionContext.Complete(result, resultCode: resultCode);
         }

src/Runner.Worker/action_yaml.json

@@ -7,8 +7,7 @@
                     "name": "string",
                     "description": "string",
                     "inputs": "inputs",
-                    "runs": "runs",
-                    "outputs": "outputs"
+                    "runs": "runs"
                 },
                 "loose-key-type": "non-empty-string",
                 "loose-value-type": "any"
@@ -29,20 +28,6 @@
                 "loose-value-type": "any"
             }
         },
-        "outputs": {
-            "mapping": {
-                "loose-key-type": "non-empty-string",
-                "loose-value-type": "outputs-attributes"
-            }
-        },
-        "outputs-attributes": {
-            "mapping": {
-                "properties": {
-                    "description": "string",
-                    "value": "output-value"
-                }
-            }
-        },
         "runs": {
             "one-of": [
                 "container-runs",
@@ -110,13 +95,19 @@
         "composite-steps": {
             "context": [
                 "github",
+                "needs",
                 "strategy",
                 "matrix",
+                "secrets",
                 "steps",
                 "inputs",
                 "job",
                 "runner",
                 "env",
+                "always(0,0)",
+                "failure(0,0)",
+                "cancelled(0,0)",
+                "success(0,0)",
                 "hashFiles(1,255)"
             ],
             "sequence": {
@@ -129,19 +120,6 @@
             ],
             "string": {}
         },
-        "output-value": {
-            "context": [
-                "github",
-                "strategy",
-                "matrix",
-                "steps",
-                "inputs",
-                "job",
-                "runner",
-                "env"
-            ],
-            "string": {}
-        },
         "input-default-context": {
             "context": [
                 "github",

src/Sdk/DTPipelines/Pipelines/ObjectTemplating/PipelineTemplateConverter.cs

@@ -264,14 +264,13 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
             return result;
         }
 
-        //Note: originally was List<Step> but we need to change to List<ActionStep> to use the "Inputs" attribute
-        internal static List<ActionStep> ConvertToSteps(
+        internal static List<Step> ConvertToSteps(
             TemplateContext context,
             TemplateToken steps)
         {
             var stepsSequence = steps.AssertSequence($"job {PipelineTemplateConstants.Steps}");
 
-            var result = new List<ActionStep>();
+            var result = new List<Step>();
             foreach (var stepsItem in stepsSequence)
             {
                 var step = ConvertToStep(context, stepsItem);
@@ -287,7 +286,7 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
             return result;
         }
 
-        private static ActionStep ConvertToStep(
+        private static Step ConvertToStep(
             TemplateContext context,
             TemplateToken stepsItem)
         {

src/Sdk/DTPipelines/Pipelines/ObjectTemplating/PipelineTemplateEvaluator.cs

@@ -159,10 +159,11 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
             return result;
         }
 
-        public List<ActionStep> LoadCompositeSteps(
+        // TODO: Change to return a variety of steps.
+        public List<Step> LoadCompositeSteps(
             TemplateToken token)
         {
-            var result = default(List<ActionStep>);
+            var result = default(List<Step>);
             if (token != null && token.Type != TokenType.Null)
             {
                 var context = CreateContext(null, null, setMissingContext: false);

src/dev.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/bash
 
 ###############################################################################
 #