Support runner groups with selected visibility in webhooks autoscaler (#1012)

The current implementation doesn't support yet runner groups with custom visibility (e.g selected repositories only). If there are multiple runner groups with selected visibility - not all runner groups may be a potential target to be scaled up. Thus this PR introduces support to allow having runner groups with selected visibility. This requires to query GitHub API to find what are the potential runner groups that are linked to a specific repository (whether using visibility all or selected).

This also improves resolving the `scaleTargetKey` that are used to match an HRA based on the inputs of the `RunnerSet`/`RunnerDeployment` spec to better support for runner groups.

This requires to configure github auth in the webhook server, to keep backwards compatibility if github auth is not provided to the webhook server, this will assume all runner groups have no selected visibility and it will target any available runner group as before

cmd/githubwebhookserver/main.go

@@ -28,6 +28,8 @@ import (
 
 	actionsv1alpha1 "github.com/actions-runner-controller/actions-runner-controller/api/v1alpha1"
 	"github.com/actions-runner-controller/actions-runner-controller/controllers"
+	"github.com/actions-runner-controller/actions-runner-controller/github"
+	"github.com/kelseyhightower/envconfig"
 	zaplib "go.uber.org/zap"
 	"k8s.io/apimachinery/pkg/runtime"
 	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
@@ -76,8 +78,17 @@ func main() {
 		enableLeaderElection bool
 		syncPeriod           time.Duration
 		logLevel             string
+
+		ghClient *github.Client
 	)
 
+	var c github.Config
+	err = envconfig.Process("github", &c)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error: processing environment variables: %v\n", err)
+		os.Exit(1)
+	}
+
 	webhookSecretTokenEnv = os.Getenv(webhookSecretTokenEnvName)
 
 	flag.StringVar(&webhookAddr, "webhook-addr", ":8000", "The address the metric endpoint binds to.")
@@ -88,6 +99,11 @@ func main() {
 	flag.DurationVar(&syncPeriod, "sync-period", 10*time.Minute, "Determines the minimum frequency at which K8s resources managed by this controller are reconciled. When you use autoscaling, set to a lower value like 10 minute, because this corresponds to the minimum time to react on demand change")
 	flag.StringVar(&logLevel, "log-level", logLevelDebug, `The verbosity of the logging. Valid values are "debug", "info", "warn", "error". Defaults to "debug".`)
 	flag.StringVar(&webhookSecretToken, "github-webhook-secret-token", "", "The personal access token of GitHub.")
+	flag.StringVar(&c.Token, "github-token", c.Token, "The personal access token of GitHub.")
+	flag.Int64Var(&c.AppID, "github-app-id", c.AppID, "The application ID of GitHub App.")
+	flag.Int64Var(&c.AppInstallationID, "github-app-installation-id", c.AppInstallationID, "The installation ID of GitHub App.")
+	flag.StringVar(&c.AppPrivateKey, "github-app-private-key", c.AppPrivateKey, "The path of a private key file to authenticate as a GitHub App")
+
 	flag.Parse()
 
 	if webhookSecretToken == "" && webhookSecretTokenEnv != "" {
@@ -121,6 +137,15 @@ func main() {
 		}
 	})
 
+	if len(c.Token) > 0 || (c.AppID > 0 && c.AppInstallationID > 0 && c.AppPrivateKey != "") {
+		ghClient, err = c.NewClient()
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "Error: Client creation failed.", err)
+			setupLog.Error(err, "unable to create controller", "controller", "Runner")
+			os.Exit(1)
+		}
+	}
+
 	ctrl.SetLogger(logger)
 
 	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{
@@ -143,6 +168,7 @@ func main() {
 		Scheme:         mgr.GetScheme(),
 		SecretKeyBytes: []byte(webhookSecretToken),
 		Namespace:      watchNamespace,
+		GitHubClient:   ghClient,
 	}
 
 	if err = hraGitHubWebhook.SetupWithManager(mgr); err != nil {