Add error handling to schedule coredns (#222)

* add kubectl function with output. add check to schedule coredns function

* remove dash from kubectl command

eks/coredns.go

@@ -1,6 +1,8 @@
 package eks
 
 import (
+	"strings"
+
 	"github.com/gruntwork-io/go-commons/errors"
 
 	"github.com/gruntwork-io/kubergrunt/eksawshelper"
@@ -43,17 +45,32 @@ func ScheduleCoredns(
 	case Fargate:
 		logger.Info("Doing fargate annotation")
 
-		err = kubectl.RunKubectl(
+		// CoreDNS may or may not have the compute-type annotation by default. Check for existence.
+		out, err := kubectl.RunKubectlWithOutput(
 			kubectlOptions,
-			"patch", "deployment", "coredns",
+			"get", "deployment", "coredns",
 			"-n", "kube-system",
-			"--type", "json",
-			"--patch", `[{"op": "remove","path": "/spec/template/metadata/annotations/eks.amazonaws.com~1compute-type"}]`,
+			"-o", `jsonpath='{.spec.template.metadata}'`,
 		)
-
 		if err != nil {
 			return errors.WithStackTrace(err)
 		}
+
+		// Only attempt to patch coredns deployment if the compute-type annotation is present. Else skip.
+		if strings.Contains(out, "compute-type") {
+			err = kubectl.RunKubectl(
+				kubectlOptions,
+				"patch", "deployment", "coredns",
+				"-n", "kube-system",
+				"--type", "json",
+				"--patch", `[{"op": "remove","path": "/spec/template/metadata/annotations/eks.amazonaws.com~1compute-type"}]`,
+			)
+
+			if err != nil {
+				return errors.WithStackTrace(err)
+			}
+		}
+
 	case EC2:
 		logger.Info("Doing ec2 annotation")
 

kubectl/command.go

@@ -34,3 +34,31 @@ func RunKubectl(options *KubectlOptions, args ...string) error {
 	_, err := shell.RunShellCommandAndGetAndStreamOutput(shellOptions, "kubectl", cmdArgs...)
 	return err
 }
+
+func RunKubectlWithOutput(options *KubectlOptions, args ...string) (string, error) {
+	shellOptions := shell.NewShellOptions()
+	cmdArgs := []string{}
+	scheme := options.AuthScheme()
+	switch scheme {
+	case ConfigBased:
+		if options.ContextName != "" {
+			cmdArgs = append(cmdArgs, "--context", options.ContextName)
+		}
+		if options.ConfigPath != "" {
+			cmdArgs = append(cmdArgs, "--kubeconfig", options.ConfigPath)
+		}
+	default:
+		tmpfile, err := options.TempConfigFromAuthInfo()
+		if tmpfile != "" {
+			// Make sure to delete the tmp file at the end
+			defer os.Remove(tmpfile)
+		}
+		if err != nil {
+			return "ERROR", err
+		}
+		cmdArgs = append(cmdArgs, "--kubeconfig", tmpfile)
+	}
+	cmdArgs = append(cmdArgs, args...)
+	out, err := shell.RunShellCommandAndGetAndStreamOutput(shellOptions, "kubectl", cmdArgs...)
+	return out, err
+}