packer: check for latest version

checkpoint.go

@@ -9,18 +9,27 @@ import (
 	"github.com/mitchellh/packer/packer"
 )
 
+func init() {
+	packer.VersionChecker = packerVersionCheck
+	checkpointResult = make(chan *checkpoint.CheckResponse, 1)
+}
+
+var checkpointResult chan *checkpoint.CheckResponse
+
 // runCheckpoint runs a HashiCorp Checkpoint request. You can read about
 // Checkpoint here: https://github.com/hashicorp/go-checkpoint.
 func runCheckpoint(c *config) {
 	// If the user doesn't want checkpoint at all, then return.
 	if c.DisableCheckpoint {
 		log.Printf("[INFO] Checkpoint disabled. Not running.")
+		checkpointResult <- nil
 		return
 	}
 
 	configDir, err := ConfigDir()
 	if err != nil {
 		log.Printf("[ERR] Checkpoint setup error: %s", err)
+		checkpointResult <- nil
 		return
 	}
 
@@ -35,7 +44,7 @@ func runCheckpoint(c *config) {
 		signaturePath = ""
 	}
 
-	_, err = checkpoint.Check(&checkpoint.CheckParams{
+	resp, err := checkpoint.Check(&checkpoint.CheckParams{
 		Product:       "packer",
 		Version:       version,
 		SignatureFile: signaturePath,
@@ -43,5 +52,29 @@ func runCheckpoint(c *config) {
 	})
 	if err != nil {
 		log.Printf("[ERR] Checkpoint error: %s", err)
+		resp = nil
 	}
+
+	checkpointResult <- resp
+}
+
+// packerVersionCheck implements packer.VersionCheckFunc and is used
+// as the version checker.
+func packerVersionCheck(current string) (packer.VersionCheckInfo, error) {
+	info := <-checkpointResult
+	if info == nil {
+		var zero packer.VersionCheckInfo
+		return zero, nil
+	}
+
+	alerts := make([]string, len(info.Alerts))
+	for i, a := range info.Alerts {
+		alerts[i] = a.Message
+	}
+
+	return packer.VersionCheckInfo{
+		Outdated: info.Outdated,
+		Latest:   info.CurrentVersion,
+		Alerts:   alerts,
+	}, nil
 }

packer/version.go

@@ -9,6 +9,12 @@ import (
 // compiler for source builds.
 var GitCommit string
 
+// This should be check to a callback to check for the latest version.
+//
+// The global nature of this variable is dirty, but a version checker
+// really shouldn't change anyways.
+var VersionChecker VersionCheckFunc
+
 // The version of packer.
 const Version = "0.6.2"
 
@@ -17,6 +23,18 @@ const Version = "0.6.2"
 // pre-release marker.
 const VersionPrerelease = "dev"
 
+// VersionCheckFunc is the callback that is called to check the latest
+// version of Packer.
+type VersionCheckFunc func(string) (VersionCheckInfo, error)
+
+// VersionCheckInfo is the return value for the VersionCheckFunc that
+// contains the latest version information.
+type VersionCheckInfo struct {
+	Outdated bool
+	Latest   string
+	Alerts   []string
+}
+
 type versionCommand byte
 
 func (versionCommand) Help() string {
@@ -30,8 +48,26 @@ func (versionCommand) Run(env Environment, args []string) int {
 	env.Ui().Machine("version", Version)
 	env.Ui().Machine("version-prelease", VersionPrerelease)
 	env.Ui().Machine("version-commit", GitCommit)
-
 	env.Ui().Say(VersionString())
+
+	if VersionChecker != nil {
+		current := Version
+		if VersionPrerelease != "" {
+			current += fmt.Sprintf(".%s", VersionPrerelease)
+		}
+
+		info, err := VersionChecker(current)
+		if err != nil {
+			env.Ui().Say(fmt.Sprintf("\nError checking latest version: %s", err))
+		}
+		if info.Outdated {
+			env.Ui().Say(fmt.Sprintf(
+				"\nYour version of Packer is out of date! The latest version\n"+
+					"is %s. You can update by downloading from www.packer.io.",
+				info.Latest))
+		}
+	}
+
 	return 0
 }