Extract checkForUpdates to its own file

prog/weaver/checkpoint.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"sync/atomic"
+	"time"
+
+	"github.com/weaveworks/go-checkpoint"
+)
+
+var checker *checkpoint.Checker
+var newVersion atomic.Value
+
+const (
+	updateCheckPeriod = 6 * time.Hour
+)
+
+func checkForUpdates() {
+	newVersion.Store("")
+
+	handleResponse := func(r *checkpoint.CheckResponse, err error) {
+		if err != nil {
+			Log.Printf("Error checking version: %v", err)
+			return
+		}
+		if r.Outdated {
+			newVersion.Store(r.CurrentVersion)
+			Log.Printf("Weave version %s is available; please update at %s",
+				r.CurrentVersion, r.CurrentDownloadURL)
+		}
+	}
+
+	// Start background version checking
+	params := checkpoint.CheckParams{
+		Product:       "weave-net",
+		Version:       version,
+		SignatureFile: "",
+	}
+	checker = checkpoint.CheckInterval(&params, updateCheckPeriod, handleResponse)
+}

prog/weaver/main.go

@@ -9,7 +9,6 @@ import (
 	"runtime"
 	"strconv"
 	"strings"
-	"sync/atomic"
 	"time"
 
 	"github.com/docker/docker/pkg/mflag"
@@ -17,7 +16,6 @@ import (
 	"github.com/pkg/profile"
 	"github.com/weaveworks/mesh"
 
-	"github.com/weaveworks/go-checkpoint"
 	"github.com/weaveworks/weave/common"
 	"github.com/weaveworks/weave/common/docker"
 	"github.com/weaveworks/weave/db"
@@ -30,8 +28,6 @@ import (
 )
 
 var version = "(unreleased version)"
-var checker *checkpoint.Checker
-var newVersion atomic.Value
 
 var Log = common.Log
 
@@ -52,34 +48,6 @@ type dnsConfig struct {
 	EffectiveListenAddress string
 }
 
-const (
-	updateCheckPeriod = 6 * time.Hour
-)
-
-func checkForUpdates() {
-	newVersion.Store("")
-
-	handleResponse := func(r *checkpoint.CheckResponse, err error) {
-		if err != nil {
-			Log.Printf("Error checking version: %v", err)
-			return
-		}
-		if r.Outdated {
-			newVersion.Store(r.CurrentVersion)
-			Log.Printf("Weave version %s is available; please update at %s",
-				r.CurrentVersion, r.CurrentDownloadURL)
-		}
-	}
-
-	// Start background version checking
-	params := checkpoint.CheckParams{
-		Product:       "weave-net",
-		Version:       version,
-		SignatureFile: "",
-	}
-	checker = checkpoint.CheckInterval(&params, updateCheckPeriod, handleResponse)
-}
-
 func (c *ipamConfig) Enabled() bool {
 	var (
 		hasPeerCount = c.PeerCount > 0