Prevent env deletion if any function exists (#2343)

* Added force deletion flag for env

pkg/fission-cli/cmd/environment/command.go

@@ -72,7 +72,7 @@ func Commands() *cobra.Command {
 	}
 	wrapper.SetFlags(deleteCmd, flag.FlagSet{
 		Required: []flag.Flag{flag.EnvName},
-		Optional: []flag.Flag{flag.NamespaceEnvironment, flag.IgnoreNotFound},
+		Optional: []flag.Flag{flag.NamespaceEnvironment, flag.IgnoreNotFound, flag.EnvForce},
 	})
 
 	listCmd := &cobra.Command{

pkg/fission-cli/cmd/environment/delete.go

@@ -42,6 +42,20 @@ func (opts *DeleteSubCommand) do(input cli.Input) error {
 		Namespace: input.String(flagkey.NamespaceEnvironment),
 	}
 
+	if !input.Bool(flagkey.EnvForce) {
+		fns, err := opts.Client().V1().Function().List(metav1.NamespaceAll)
+		if err != nil {
+			return errors.Wrap(err, "Error getting functions wrt environment.")
+		}
+
+		for _, fn := range fns {
+			if fn.Spec.Environment.Name == m.Name &&
+				fn.Spec.Environment.Namespace == m.Namespace {
+				return errors.New("Environment is used by atleast one function.")
+			}
+		}
+	}
+
 	err := opts.Client().V1().Environment().Delete(m)
 	if err != nil {
 		if input.Bool(flagkey.IgnoreNotFound) && util.IsNotFound(err) {
@@ -51,5 +65,6 @@ func (opts *DeleteSubCommand) do(input cli.Input) error {
 	}
 
 	fmt.Printf("environment '%v' deleted\n", m.Name)
+
 	return nil
 }