Skips checking for readiness on CNI DEL (and instead warns)

Because deletes should favor a successful path, the readiness check should be skipped for pod removals.

This can cause an issue where there's pods pending deletes and that might impact scheduling of a pod that may be necessary in order to set the readiness indicator.

Adds a new method  to check for readiness indicator alone in order to immediately log a warning.

pkg/multus/multus.go

@@ -815,8 +815,13 @@ func CmdDel(args *skel.CmdArgs, exec invoke.Exec, kubeClient *k8s.ClientInfo) er
 	}
 
 	if in.ReadinessIndicatorFile != "" {
-		if err := types.GetReadinessIndicatorFile(in.ReadinessIndicatorFile); err != nil {
-			return cmdErr(k8sArgs, "PollImmediate error waiting for ReadinessIndicatorFile (on del): %v", err)
+		readinessfileexists, err := types.ReadinessIndicatorExistsNow(in.ReadinessIndicatorFile)
+		if err != nil {
+			return cmdErr(k8sArgs, "error checking readinessindicatorfile @ %v: %v", in.ReadinessIndicatorFile, err)
+		} else {
+			if !readinessfileexists {
+				logging.Verbosef("warning: readinessindicatorfile @ %v does not exist", in.ReadinessIndicatorFile)
+			}
 		}
 	}
 

pkg/types/conf.go

@@ -618,3 +618,14 @@ func GetReadinessIndicatorFile(readinessIndicatorFile string) error {
 		return err == nil, nil
 	})
 }
+
+func ReadinessIndicatorExistsNow(readinessIndicatorFile string) (bool, error) {
+	_, err := os.Stat(readinessIndicatorFile)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return false, nil
+		}
+		return false, err
+	}
+	return true, nil
+}