feat(helm): add ability for --dry-run to do lookup functions

When a helm command is run with the --dry-run flag, it will try to connect to the cluster
if the value is 'server' to be able to render lookup functions.
Closes #8137

Signed-off-by: Tapas Kapadia <tapaskapadia10@gmail.com>

cmd/helm/install.go

@@ -263,7 +263,7 @@ func runInstall(args []string, client *action.Install, valueOpts *values.Options
 	client.Namespace = settings.Namespace()
 
 	// validate dry-run flag value is one of the allowed values
-	if err := validateDryRunFlag(client); err != nil {
+	if err := validateDryRunFlag(client.DryRun); err != nil {
 		return nil, err
 	}
 
@@ -308,12 +308,12 @@ func compInstall(args []string, toComplete string, client *action.Install) ([]st
 	return nil, cobra.ShellCompDirectiveNoFileComp
 }
 
-func validateDryRunFlag(client *action.Install) error {
+func validateDryRunFlag(dryRunFlagValue string) error {
 	// validate dry-run flag value with set of allowed value
 	allowedDryRunValues := []string{"false", "true", "none", "client", "server"}
 	isAllowed := false
 	for _, v := range allowedDryRunValues {
-		if client.DryRun == v {
+		if dryRunFlagValue == v {
 			isAllowed = true
 			break
 		}

cmd/helm/upgrade.go

@@ -120,11 +120,6 @@ func newUpgradeCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 					instClient.Description = client.Description
 					instClient.DependencyUpdate = client.DependencyUpdate
 
-					// validate dry-run flag value is one of the allowed values
-					if err := validateDryRunFlag(instClient); err != nil {
-						return err
-					}
-
 					rel, err := runInstall(args, instClient, valueOpts, out)
 					if err != nil {
 						return err
@@ -144,6 +139,10 @@ func newUpgradeCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 			if err != nil {
 				return err
 			}
+			// validate dry-run flag value is one of the allowed values
+			if err := validateDryRunFlag(client.DryRun); err != nil {
+				return err
+			}
 
 			p := getter.All(settings)
 			vals, err := valueOpts.MergeValues(p)