Move checkpoint into its own file to make it easy

checkpoint.go

+package main
+
+import (
+	"fmt"
+	"log"
+	"path/filepath"
+
+	"github.com/hashicorp/go-checkpoint"
+	"github.com/mitchellh/packer/packer"
+)
+
+func runCheckpoint(c *config) {
+	configDir, err := ConfigDir()
+	if err != nil {
+		log.Printf("[ERR] Checkpoint setup error: %s", err)
+		return
+	}
+
+	version := packer.Version
+	if packer.VersionPrerelease != "" {
+		version += fmt.Sprintf(".%s", packer.VersionPrerelease)
+	}
+
+	_, err = checkpoint.Check(&checkpoint.CheckParams{
+		Product:       "packer",
+		Version:       version,
+		SignatureFile: filepath.Join(configDir, "checkpoint_signature"),
+		CacheFile:     filepath.Join(configDir, "checkpoint_cache"),
+	})
+	if err != nil {
+		log.Printf("[ERR] Checkpoint error: %s", err)
+	}
+}

packer.go

@@ -10,7 +10,6 @@ import (
 	"path/filepath"
 	"runtime"
 
-	"github.com/hashicorp/go-checkpoint"
 	"github.com/mitchellh/packer/packer"
 	"github.com/mitchellh/packer/packer/plugin"
 	"github.com/mitchellh/panicwrap"
@@ -95,23 +94,8 @@ func wrappedMain() int {
 	}
 	log.Printf("Packer config: %+v", config)
 
-	configDir, err := ConfigDir()
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "Error loading config dir: \n\n%s\n", err)
-		return 1
-	}
-
 	// Fire off the checkpoint.
-	version := packer.Version
-	if packer.VersionPrerelease != "" {
-		version += fmt.Sprintf(".%s", packer.VersionPrerelease)
-	}
-	go checkpoint.Check(&checkpoint.CheckParams{
-		Product:       "packer",
-		Version:       version,
-		SignatureFile: filepath.Join(configDir, "checkpoint_signature"),
-		CacheFile:     filepath.Join(configDir, "checkpoint_cache"),
-	})
+	go runCheckpoint(config)
 
 	cacheDir := os.Getenv("PACKER_CACHE_DIR")
 	if cacheDir == "" {