Reuse docker client instance in plugin

Instead of creating a new one, reuse one created in weaver.

The change removes the pinning of client API versions (1.21 in our
case).

plugin/plugin.go

@@ -20,31 +20,14 @@ import (
 
 var Log = common.Log
 
-func Start(weaveAPIAddr string, dockerAPIAddr string, address string, meshAddress string) {
+func Start(weaveAPIAddr string, dockerClient *docker.Client, address string, meshAddress string) {
 	weave := weaveapi.NewClient(weaveAPIAddr, Log)
 
-	var dockerClient *docker.Client
-	var err error
-	if dockerAPIAddr != "" {
-		// API 1.21 is the first version that supports docker network commands
-		dockerClient, err = docker.NewVersionedClient(dockerAPIAddr, "1.21")
-		if err != nil {
-			Log.Fatalf("unable to connect to docker: %s", err)
-		}
-	}
-
-	if dockerClient == nil {
-		Log.Info("Running without Docker API connection")
-	} else {
-		Log.Info(dockerClient.Info())
-	}
-
 	Log.Info("Waiting for Weave API Server...")
 	weave.WaitAPIServer(30)
 	Log.Info("Finished waiting for Weave API Server")
 
-	err = run(dockerClient, weave, address, meshAddress)
-	if err != nil {
+	if err := run(dockerClient, weave, address, meshAddress); err != nil {
 		Log.Fatal(err)
 	}
 }

prog/plugin-v2/launch.sh

@@ -47,7 +47,8 @@ if [ -z "$IPALLOC_INIT" ]; then
 fi
 
 exec /home/weave/weaver $EXTRA_ARGS --port=6783 $BRIDGE_OPTIONS \
-    --http-addr=$HTTP_ADDR --status-addr=$STATUS_ADDR --docker-api='' --no-dns \
+    --http-addr=$HTTP_ADDR --status-addr=$STATUS_ADDR \
+    --no-dns \
     --ipalloc-range=$IPALLOC_RANGE \
     --ipalloc-init $IPALLOC_INIT \
     --nickname "$(hostname)" \

prog/weaver/main.go

@@ -405,7 +405,7 @@ func main() {
 	}
 
 	if enablePlugin {
-		go plugin.Start(httpAddr, dockerAPI, pluginSocket, pluginMeshSocket)
+		go plugin.Start(httpAddr, dockerCli, pluginSocket, pluginMeshSocket)
 	}
 
 	signals.SignalHandlerLoop(common.Log, router)