feat: Repository-wide RunnerDeployment Autoscaling (#57)

* feat: Repository-wide RunnerDeployment Autoscaling

This adds `maxReplicas` and `minReplicas` to the RunnerDeploymentSpec. If and only if both fields are set, the controller computes and sets desired `replicas` automatically depending on the demand.

The number of demanded runner replicas is computed by `queued workflow runs + in_progress workflow runs` for the repository. The support for organizational runners is not included.

Ref https://github.com/summerwind/actions-runner-controller/issues/10

api/v1alpha1/runnerdeployment_types.go

@@ -22,7 +22,21 @@ import (
 
 // RunnerReplicaSetSpec defines the desired state of RunnerDeployment
 type RunnerDeploymentSpec struct {
-	Replicas *int `json:"replicas"`
+	// +optional
+	Replicas *int `json:"replicas,omitempty"`
+
+	// MinReplicas is the minimum number of replicas the deployment is allowed to scale
+	// +optional
+	MinReplicas *int `json:"minReplicas,omitempty"`
+
+	// MinReplicas is the maximum number of replicas the deployment is allowed to scale
+	// +optional
+	MaxReplicas *int `json:"maxReplicas,omitempty"`
+
+	// ScaleDownDelaySecondsAfterScaleUp is the approximate delay for a scale down followed by a scale up
+	// Used to prevent flapping (down->up->down->... loop)
+	// +optional
+	ScaleDownDelaySecondsAfterScaleUp *int `json:"scaleDownDelaySecondsAfterScaleOut,omitempty"`
 
 	Template RunnerTemplate `json:"template"`
 }
@@ -30,6 +44,14 @@ type RunnerDeploymentSpec struct {
 type RunnerDeploymentStatus struct {
 	AvailableReplicas int `json:"availableReplicas"`
 	ReadyReplicas     int `json:"readyReplicas"`
+
+	// Replicas is the total number of desired, non-terminated and latest pods to be set for the primary RunnerSet
+	// This doesn't include outdated pods while upgrading the deployment and replacing the runnerset.
+	// +optional
+	Replicas *int `json:"desiredReplicas,omitempty"`
+
+	// +optional
+	LastSuccessfulScaleOutTime *metav1.Time `json:"lastSuccessfulScaleOutTime,omitempty"`
 }
 
 // +kubebuilder:object:root=true

api/v1alpha1/zz_generated.deepcopy.go

@@ -58,7 +58,7 @@ func (in *RunnerDeployment) DeepCopyInto(out *RunnerDeployment) {
 	out.TypeMeta = in.TypeMeta
 	in.ObjectMeta.DeepCopyInto(&out.ObjectMeta)
 	in.Spec.DeepCopyInto(&out.Spec)
-	out.Status = in.Status
+	in.Status.DeepCopyInto(&out.Status)
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new RunnerDeployment.
@@ -119,6 +119,21 @@ func (in *RunnerDeploymentSpec) DeepCopyInto(out *RunnerDeploymentSpec) {
 		*out = new(int)
 		**out = **in
 	}
+	if in.MinReplicas != nil {
+		in, out := &in.MinReplicas, &out.MinReplicas
+		*out = new(int)
+		**out = **in
+	}
+	if in.MaxReplicas != nil {
+		in, out := &in.MaxReplicas, &out.MaxReplicas
+		*out = new(int)
+		**out = **in
+	}
+	if in.ScaleDownDelaySecondsAfterScaleUp != nil {
+		in, out := &in.ScaleDownDelaySecondsAfterScaleUp, &out.ScaleDownDelaySecondsAfterScaleUp
+		*out = new(int)
+		**out = **in
+	}
 	in.Template.DeepCopyInto(&out.Template)
 }
 
@@ -135,6 +150,15 @@ func (in *RunnerDeploymentSpec) DeepCopy() *RunnerDeploymentSpec {
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *RunnerDeploymentStatus) DeepCopyInto(out *RunnerDeploymentStatus) {
 	*out = *in
+	if in.Replicas != nil {
+		in, out := &in.Replicas, &out.Replicas
+		*out = new(int)
+		**out = **in
+	}
+	if in.LastSuccessfulScaleOutTime != nil {
+		in, out := &in.LastSuccessfulScaleOutTime, &out.LastSuccessfulScaleOutTime
+		*out = (*in).DeepCopy()
+	}
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new RunnerDeploymentStatus.