feat: Surface container and template name in emissary error message. F…

…ixes #7780 (#7807)

Signed-off-by: Alex Collins <alex_collins@intuit.com>

workflow/controller/workflowpod.go

@@ -428,7 +428,7 @@ func (woc *wfOperationCtx) createWorkflowPod(ctx context.Context, nodeName strin
 				}
 			}
 			if len(c.Command) == 0 {
-				return nil, fmt.Errorf("when using the emissary executor you must either explicitly specify the command, or list the image's command in the index: https://argoproj.github.io/argo-workflows/workflow-executors/#emissary-emissary")
+				return nil, fmt.Errorf("container %q in template %q, does not have the command specified: when using the emissary executor you must either explicitly specify the command, or list the image's command in the index: https://argoproj.github.io/argo-workflows/workflow-executors/#emissary-emissary", c.Name, tmpl.Name)
 			}
 			c.Command = append([]string{"/var/run/argo/argoexec", "emissary", "--"}, c.Command...)
 		}

workflow/controller/workflowpod_test.go

@@ -654,8 +654,8 @@ func Test_createWorkflowPod_emissary(t *testing.T) {
 	t.Run("NoCommand", func(t *testing.T) {
 		woc := newWoc()
 		woc.controller.containerRuntimeExecutor = common.ContainerRuntimeExecutorEmissary
-		_, err := woc.createWorkflowPod(context.Background(), "", []apiv1.Container{{}}, &wfv1.Template{}, &createWorkflowPodOpts{})
-		assert.Error(t, err)
+		_, err := woc.createWorkflowPod(context.Background(), "", []apiv1.Container{{}}, &wfv1.Template{Name: "my-tmpl"}, &createWorkflowPodOpts{})
+		assert.EqualError(t, err, "container \"main\" in template \"my-tmpl\", does not have the command specified: when using the emissary executor you must either explicitly specify the command, or list the image's command in the index: https://argoproj.github.io/argo-workflows/workflow-executors/#emissary-emissary")
 	})
 	t.Run("CommandNoArgs", func(t *testing.T) {
 		woc := newWoc()