packer/rpc: Support Hooks

packer/hook.go

@@ -6,7 +6,8 @@ package packer
 // Run is called when the hook is called, with the name of the hook and
 // arbitrary data associated with it. To know what format the data is in,
 // you must reference the documentation for the specific hook you're interested
-// in.
+// in. In addition to that, the Hook is given access to a UI so that it can
+// output things to the user.
 type Hook interface {
-	Run(string, interface{})
+	Run(string, interface{}, Ui)
 }

packer/hook_test.go

@@ -4,6 +4,6 @@ type TestHook struct {
 	runCalled bool
 }
 
-func (t *TestHook) Run(string, interface{}) {
+func (t *TestHook) Run(string, interface{}, Ui) {
 	t.runCalled = true
 }

packer/rpc/environment.go

@@ -43,6 +43,23 @@ func (e *Environment) Cli(args []string) (result int, err error) {
 	return
 }
 
+func (e *Environment) Hook(name string) (h packer.Hook, err error) {
+	var reply string
+	err = e.client.Call("Environment.Hook", name, &reply)
+	if err != nil {
+		return
+	}
+
+	_, err = rpc.Dial("tcp", reply)
+	if err != nil {
+		return
+	}
+
+	// TODO: Hook
+	h = nil
+	return
+}
+
 func (e *Environment) Ui() packer.Ui {
 	var reply string
 	e.client.Call("Environment.Ui", new(interface{}), &reply)
@@ -71,6 +88,20 @@ func (e *EnvironmentServer) Cli(args *EnvironmentCliArgs, reply *int) (err error
 	return
 }
 
+func (e *EnvironmentServer) Hook(name *string, reply *string) error {
+	_, err := e.env.Hook(*name)
+	if err != nil {
+		return err
+	}
+
+	// Wrap it
+	// TODO: Register hook
+	server := rpc.NewServer()
+
+	*reply = serveSingleConn(server)
+	return nil
+}
+
 func (e *EnvironmentServer) Ui(args *interface{}, reply *string) error {
 	ui := e.env.Ui()
 

packer/rpc/environment_test.go

@@ -15,6 +15,8 @@ type testEnvironment struct {
 	builderName   string
 	cliCalled     bool
 	cliArgs       []string
+	hookCalled    bool
+	hookName      string
 	uiCalled      bool
 }
 
@@ -30,6 +32,12 @@ func (e *testEnvironment) Cli(args []string) (int, error) {
 	return 42, nil
 }
 
+func (e *testEnvironment) Hook(name string) (packer.Hook, error) {
+	e.hookCalled = true
+	e.hookName = name
+	return nil, nil
+}
+
 func (e *testEnvironment) Ui() packer.Ui {
 	e.uiCalled = true
 	return testEnvUi

packer/rpc/hook.go

@@ -0,0 +1,50 @@
+package rpc
+
+import (
+	"github.com/mitchellh/packer/packer"
+	"net/rpc"
+)
+
+// An implementation of packer.Hook where the hook is actually executed
+// over an RPC connection.
+type hook struct {
+	client *rpc.Client
+}
+
+// HookServer wraps a packer.Hook implementation and makes it exportable
+// as part of a Golang RPC server.
+type HookServer struct {
+	hook packer.Hook
+}
+
+type HookRunArgs struct {
+	Name string
+	Data interface{}
+	RPCAddress string
+}
+
+func Hook(client *rpc.Client) *hook {
+	return &hook{client}
+}
+
+func (h *hook) Run(name string, data interface{}, ui packer.Ui) {
+	server := rpc.NewServer()
+	RegisterUi(server, ui)
+	address := serveSingleConn(server)
+
+	args := &HookRunArgs{name, data, address}
+	h.client.Call("Hook.Run", args, new(interface{}))
+	return
+}
+
+func (h *HookServer) Run(args *HookRunArgs, reply *interface{}) error {
+	client, err := rpc.Dial("tcp", args.RPCAddress)
+	if err != nil {
+		return err
+	}
+
+	h.hook.Run(args.Name, args.Data, &Ui{client})
+
+	*reply = nil
+	return nil
+}

packer/rpc/hook_test.go

@@ -0,0 +1,49 @@
+package rpc
+
+import (
+	"cgl.tideland.biz/asserts"
+	"github.com/mitchellh/packer/packer"
+	"net/rpc"
+	"testing"
+)
+
+type testHook struct {
+	runCalled     bool
+	runUi         packer.Ui
+}
+
+func (h *testHook) Run(name string, data interface{}, ui packer.Ui) {
+	h.runCalled = true
+}
+
+func TestHookRPC(t *testing.T) {
+	assert := asserts.NewTestingAsserts(t, true)
+
+	// Create the UI to test
+	h := new(testHook)
+
+	// Serve
+	server := rpc.NewServer()
+	RegisterHook(server, h)
+	address := serveSingleConn(server)
+
+	// Create the client over RPC and run some methods to verify it works
+	client, err := rpc.Dial("tcp", address)
+	assert.Nil(err, "should be able to connect")
+
+	hClient := Hook(client)
+
+	// Test Run
+	ui := &testUi{}
+	hClient.Run("foo", 42, ui)
+	assert.True(h.runCalled, "run should be called")
+}
+
+func TestHook_Implements(t *testing.T) {
+	assert := asserts.NewTestingAsserts(t, true)
+
+	var r packer.Hook
+	h := &hook{nil}
+
+	assert.Implementor(h, &r, "should be a Hook")
+}

packer/rpc/server.go

@@ -29,6 +29,12 @@ func RegisterEnvironment(s *rpc.Server, e packer.Environment) {
 	s.RegisterName("Environment", &EnvironmentServer{e})
 }
 
+// Registers the appropriate endpoint on an RPC server to serve a
+// Hook.
+func RegisterHook(s *rpc.Server, hook packer.Hook) {
+	s.RegisterName("Hook", &HookServer{hook})
+}
+
 // Registers the appropriate endpoint on an RPC server to serve a
 // Packer UI
 func RegisterUi(s *rpc.Server, ui packer.Ui) {