Integrate CLI plugins with `docker help «foo»`

Signed-off-by: Ian Campbell <ijc@docker.com>

cmd/docker/docker.go

@@ -103,6 +103,18 @@ func setupHelpCommand(dockerCli *command.DockerCli, rootCmd, helpCmd *cobra.Comm
 			return err
 		}
 
+		if len(args) > 0 {
+			helpcmd, err := pluginmanager.PluginRunCommand(dockerCli, args[0], rootCmd)
+			if err == nil {
+				err = helpcmd.Run()
+				if err != nil {
+					return err
+				}
+			}
+			if !pluginmanager.IsNotFound(err) {
+				return err
+			}
+		}
 		if origRunE != nil {
 			return origRunE(c, args)
 		}

e2e/cli-plugins/run_test.go

@@ -22,6 +22,19 @@ func TestRunNonexisting(t *testing.T) {
 	golden.Assert(t, res.Stderr(), "docker-nonexistent-err.golden")
 }
 
+// TestHelpNonexisting ensures correct behaviour when invoking help on a nonexistent plugin.
+func TestHelpNonexisting(t *testing.T) {
+	run, cleanup := prepare(t)
+	defer cleanup()
+
+	res := icmd.RunCmd(run("help", "nonexistent"))
+	res.Assert(t, icmd.Expected{
+		ExitCode: 1,
+	})
+	assert.Assert(t, is.Equal(res.Stdout(), ""))
+	golden.Assert(t, res.Stderr(), "docker-help-nonexistent-err.golden")
+}
+
 // TestRunBad ensures correct behaviour when running an existent but invalid plugin
 func TestRunBad(t *testing.T) {
 	run, cleanup := prepare(t)
@@ -35,6 +48,19 @@ func TestRunBad(t *testing.T) {
 	golden.Assert(t, res.Stderr(), "docker-badmeta-err.golden")
 }
 
+// TestHelpBad ensures correct behaviour when invoking help on a existent but invalid plugin.
+func TestHelpBad(t *testing.T) {
+	run, cleanup := prepare(t)
+	defer cleanup()
+
+	res := icmd.RunCmd(run("help", "badmeta"))
+	res.Assert(t, icmd.Expected{
+		ExitCode: 1,
+	})
+	assert.Assert(t, is.Equal(res.Stdout(), ""))
+	golden.Assert(t, res.Stderr(), "docker-help-badmeta-err.golden")
+}
+
 // TestRunGood ensures correct behaviour when running a valid plugin
 func TestRunGood(t *testing.T) {
 	run, cleanup := prepare(t)
@@ -47,6 +73,19 @@ func TestRunGood(t *testing.T) {
 	})
 }
 
+// TestHelpGood ensures correct behaviour when invoking help on a
+// valid plugin. A global argument is included to ensure it does not
+// interfere.
+func TestHelpGood(t *testing.T) {
+	run, cleanup := prepare(t)
+	defer cleanup()
+
+	res := icmd.RunCmd(run("-D", "help", "helloworld"))
+	res.Assert(t, icmd.Success)
+	golden.Assert(t, res.Stdout(), "docker-help-helloworld.golden")
+	assert.Assert(t, is.Equal(res.Stderr(), ""))
+}
+
 // TestRunGoodSubcommand ensures correct behaviour when running a valid plugin with a subcommand
 func TestRunGoodSubcommand(t *testing.T) {
 	run, cleanup := prepare(t)
@@ -58,3 +97,16 @@ func TestRunGoodSubcommand(t *testing.T) {
 		Out:      "Goodbye World!",
 	})
 }
+
+// TestHelpGoodSubcommand ensures correct behaviour when invoking help on a
+// valid plugin subcommand. A global argument is included to ensure it does not
+// interfere.
+func TestHelpGoodSubcommand(t *testing.T) {
+	run, cleanup := prepare(t)
+	defer cleanup()
+
+	res := icmd.RunCmd(run("-D", "help", "helloworld", "goodbye"))
+	res.Assert(t, icmd.Success)
+	golden.Assert(t, res.Stdout(), "docker-help-helloworld-goodbye.golden")
+	assert.Assert(t, is.Equal(res.Stderr(), ""))
+}

e2e/cli-plugins/testdata/docker-help-badmeta-err.golden

@@ -0,0 +1 @@
+unknown help topic: badmeta

e2e/cli-plugins/testdata/docker-help-helloworld-goodbye.golden

@@ -0,0 +1,4 @@
+
+Usage:	docker helloworld goodbye
+
+Say Goodbye instead of Hello

e2e/cli-plugins/testdata/docker-help-helloworld.golden

@@ -0,0 +1,9 @@
+
+Usage:	docker helloworld COMMAND
+
+A basic Hello World plugin for tests
+
+Commands:
+  goodbye     Say Goodbye instead of Hello
+
+Run 'docker helloworld COMMAND --help' for more information on a command.

e2e/cli-plugins/testdata/docker-help-nonexistent-err.golden

@@ -0,0 +1 @@
+unknown help topic: nonexistent