feat: expose if docker is enabled and wait for docker to be ready (#962)

Resolves #897
Resolves #915

controllers/runner_controller.go

@@ -782,6 +782,8 @@ func newRunnerPod(template corev1.Pod, runnerSpec v1alpha1.RunnerConfig, default
 		dockerRegistryMirror = *runnerSpec.DockerRegistryMirror
 	}
 
+	// Be aware some of the environment variables are used
+	// in the runner entrypoint script
 	env := []corev1.EnvVar{
 		{
 			Name:  EnvVarOrg,
@@ -803,6 +805,10 @@ func newRunnerPod(template corev1.Pod, runnerSpec v1alpha1.RunnerConfig, default
 			Name:  "RUNNER_GROUP",
 			Value: runnerSpec.Group,
 		},
+		{
+			Name:  "DOCKER_ENABLED",
+			Value: fmt.Sprintf("%v", dockerEnabled || dockerdInRunner),
+		},
 		{
 			Name:  "DOCKERD_IN_RUNNER",
 			Value: fmt.Sprintf("%v", dockerdInRunner),