Prevent deployment from rolling update due to different instance-id (#1454)

The pod template is embedded inside the deployment. So if
the pod annotation contains instance-id, the deployment
will get updated and thus triggers a rolling update whenever
a new executor starts which is unwanted.

After this PR, poolmanager will patches instance-id when a
pod is chosen for a function.

For newdeploy, unlike poolmanager manages the lifecycle
of function pod directly, newdeploy is only responsible
to create the deployment so we append instance-id to top-
level controller (deployment) only.

pkg/executor/util/util.go

@@ -31,7 +31,9 @@ import (
 // when creating the environment deployment since kubelet will retry to
 // pull image until successes.
 func ApplyImagePullSecret(secret string, podspec apiv1.PodSpec) *apiv1.PodSpec {
-	podspec.ImagePullSecrets = []apiv1.LocalObjectReference{{Name: secret}}
+	if len(secret) > 0 {
+		podspec.ImagePullSecrets = []apiv1.LocalObjectReference{{Name: secret}}
+	}
 	return &podspec
 }