packer/plugin: Support PostProcessor

packer/plugin/client.go

@@ -143,13 +143,12 @@ func (c *Client) Hook() (packer.Hook, error) {
 // Returns a post-processor implementation that is communicating over
 // this client. If the client hasn't been started, this will start it.
 func (c *Client) PostProcessor() (packer.PostProcessor, error) {
-	_, err := c.rpcClient()
+	client, err := c.rpcClient()
 	if err != nil {
 		return nil, err
 	}
 
-	// TODO
-	return nil, nil
+	return &cmdPostProcessor{packrpc.PostProcessor(client), c}, nil
 }
 
 // Returns a provisioner implementation that is communicating over this

packer/plugin/plugin.go

@@ -137,6 +137,19 @@ func ServeHook(hook packer.Hook) {
 	}
 }
 
+// Serves a post-processor from a plugin.
+func ServePostProcessor(p packer.PostProcessor) {
+	log.Println("Preparing to serve a post-processor plugin...")
+
+	server := rpc.NewServer()
+	packrpc.RegisterPostProcessor(server, p)
+
+	swallowInterrupts()
+	if err := serve(server); err != nil {
+		log.Panic(err)
+	}
+}
+
 // Serves a provisioner from a plugin.
 func ServeProvisioner(p packer.Provisioner) {
 	log.Println("Preparing to serve a provisioner plugin...")

packer/plugin/plugin_test.go

@@ -59,6 +59,8 @@ func TestHelperProcess(*testing.T) {
 	case "mock":
 		fmt.Println(":1234")
 		<-make(chan int)
+	case "post-processor":
+		ServePostProcessor(new(helperPostProcessor))
 	case "provisioner":
 		ServeProvisioner(new(helperProvisioner))
 	case "start-timeout":

packer/plugin/post_processor.go

@@ -0,0 +1,37 @@
+package plugin
+
+import (
+	"github.com/mitchellh/packer/packer"
+	"log"
+)
+
+type cmdPostProcessor struct {
+	p      packer.PostProcessor
+	client *Client
+}
+
+func (c *cmdPostProcessor) Configure(config interface{}) error {
+	defer func() {
+		r := recover()
+		c.checkExit(r, nil)
+	}()
+
+	return c.p.Configure(config)
+}
+
+func (c *cmdPostProcessor) PostProcess(a packer.Artifact) (packer.Artifact, error) {
+	defer func() {
+		r := recover()
+		c.checkExit(r, nil)
+	}()
+
+	return c.p.PostProcess(a)
+}
+
+func (c *cmdPostProcessor) checkExit(p interface{}, cb func()) {
+	if c.client.Exited() {
+		cb()
+	} else if p != nil {
+		log.Panic(p)
+	}
+}

packer/plugin/post_processor_test.go

@@ -0,0 +1,37 @@
+package plugin
+
+import (
+	"github.com/mitchellh/packer/packer"
+	"os/exec"
+	"testing"
+)
+
+type helperPostProcessor byte
+
+func (helperPostProcessor) Configure(interface{}) error {
+	return nil
+}
+
+func (helperPostProcessor) PostProcess(packer.Artifact) (packer.Artifact, error) {
+	return nil, nil
+}
+
+func TestPostProcessor_NoExist(t *testing.T) {
+	c := NewClient(&ClientConfig{Cmd: exec.Command("i-should-not-exist")})
+	defer c.Kill()
+
+	_, err := c.PostProcessor()
+	if err == nil {
+		t.Fatal("should have error")
+	}
+}
+
+func TestPostProcessor_Good(t *testing.T) {
+	c := NewClient(&ClientConfig{Cmd: helperProcess("post-processor")})
+	defer c.Kill()
+
+	_, err := c.PostProcessor()
+	if err != nil {
+		t.Fatalf("should not have error: %s", err)
+	}
+}