Add POC of GitHub Webhook Delivery Forwarder (#682)

* Add POC of GitHub Webhook Delivery Forwarder

* multi-forwarder and ctrl-c existing and fix for non-woring http post

* Rename source files

* Extract signal handling into a dedicated source file

* Faster ctrl-c handling

* Enable automatic creation of repo hook on startup

* Add support for forwarding org hook deliveries

* Set hook secret on hook creation via envvar (HOOK_SECRET)

* Fix org hook support

* Fix HOOK_SECRET for consistency

* Refactor to prepare for custom log position provider

* Refactor to extract inmemory log position provider

* Add configmap-based log position provider

* Rename githubwebhookdeliveryforwarder to hookdeliveryforwarder

* Refactor to rename LogPositionProvider to Checkpointer and extract ConfigMap checkpointer into a dedicated pkg

* Refactor to extract logger initialization

* Add hookdeliveryforwarder README and bump go-github to unreleased ver

pkg/hookdeliveryforwarder/cmd/main.go

@@ -0,0 +1,95 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+
+	"github.com/actions-runner-controller/actions-runner-controller/pkg/hookdeliveryforwarder"
+	"github.com/actions-runner-controller/actions-runner-controller/pkg/hookdeliveryforwarder/configmap"
+	"github.com/go-logr/logr"
+	zaplib "go.uber.org/zap"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
+	_ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
+
+	"sigs.k8s.io/controller-runtime/pkg/log/zap"
+)
+
+const (
+	logLevelDebug = "debug"
+	logLevelInfo  = "info"
+	logLevelWarn  = "warn"
+	logLevelError = "error"
+)
+
+var (
+	scheme = runtime.NewScheme()
+)
+
+func init() {
+	_ = clientgoscheme.AddToScheme(scheme)
+}
+
+func main() {
+	var (
+		logLevel string
+
+		checkpointerConfig configmap.Config
+	)
+
+	flag.StringVar(&logLevel, "log-level", logLevelDebug, `The verbosity of the logging. Valid values are "debug", "info", "warn", "error". Defaults to "debug".`)
+
+	checkpointerConfig.InitFlags(flag.CommandLine)
+
+	config := &hookdeliveryforwarder.Config{}
+
+	config.InitFlags((flag.CommandLine))
+
+	flag.Parse()
+
+	logger := newZapLogger(logLevel)
+
+	checkpointerConfig.Scheme = scheme
+	checkpointerConfig.Logger = logger
+
+	p, mgr, err := configmap.New(&checkpointerConfig)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "%v\n", err)
+		os.Exit(1)
+	}
+
+	// TODO: Set to something that is backed by a CRD so that
+	// restarting the forwarder doesn't result in missing deliveries.
+	config.Checkpointer = p
+
+	ctx := hookdeliveryforwarder.SetupSignalHandler()
+
+	go func() {
+		if err := mgr.Start(ctx); err != nil {
+			fmt.Fprintf(os.Stderr, "problem running manager: %v\n", err)
+			os.Exit(1)
+		}
+	}()
+
+	hookdeliveryforwarder.Run(ctx, config)
+}
+
+func newZapLogger(logLevel string) logr.Logger {
+	return zap.New(func(o *zap.Options) {
+		switch logLevel {
+		case logLevelDebug:
+			o.Development = true
+		case logLevelInfo:
+			lvl := zaplib.NewAtomicLevelAt(zaplib.InfoLevel)
+			o.Level = &lvl
+		case logLevelWarn:
+			lvl := zaplib.NewAtomicLevelAt(zaplib.WarnLevel)
+			o.Level = &lvl
+		case logLevelError:
+			lvl := zaplib.NewAtomicLevelAt(zaplib.ErrorLevel)
+			o.Level = &lvl
+		}
+	})
+}