Merge pull request #1794 from weaveworks/warn-stop-plugin

Warn user if weave network is in use on stop or reset of plugin

common/docker/client.go

@@ -2,9 +2,10 @@ package docker
 
 import (
 	"errors"
+	"fmt"
 	"strings"
 
-	"github.com/fsouza/go-dockerclient"
+	docker "github.com/fsouza/go-dockerclient"
 
 	. "github.com/weaveworks/weave/common"
 )
@@ -57,12 +58,16 @@ func NewVersionedClientFromEnv(apiVersionString string) (*Client, error) {
 }
 
 func (c *Client) checkWorking() error {
-	env, err := c.Version()
-	if err != nil {
-		return err
+	_, err := c.Version()
+	return err
+}
+
+func (c *Client) Info() string {
+	if env, err := c.Version(); err != nil {
+		return fmt.Sprintf("Docker API error: %s", err)
+	} else {
+		return fmt.Sprintf("Docker API on %s: %v", c.Endpoint(), env)
 	}
-	Log.Infof("[docker] Using Docker API on %s: %v", c.Endpoint(), env)
-	return nil
 }
 
 // AddObserver adds an observer for docker events

prog/plugin/main.go

@@ -29,6 +29,7 @@ func main() {
 		logLevel         string
 		meshNetworkName  string
 		noMulticastRoute bool
+		removeNetwork    bool
 	)
 
 	flag.BoolVar(&justVersion, "version", false, "print version and exit")
@@ -38,6 +39,7 @@ func main() {
 	flag.StringVar(&meshAddress, "meshsocket", "/run/docker/plugins/weavemesh.sock", "socket on which to listen in mesh mode")
 	flag.StringVar(&meshNetworkName, "mesh-network-name", "weave", "network name to create in mesh mode")
 	flag.BoolVar(&noMulticastRoute, "no-multicast-route", false, "do not add a multicast route to network endpoints")
+	flag.BoolVar(&removeNetwork, "remove-network", false, "remove mesh network and exit")
 
 	flag.Parse()
 
@@ -48,14 +50,25 @@ func main() {
 
 	SetLogLevel(logLevel)
 
-	Log.Println("Weave plugin", version, "Command line options:", os.Args[1:])
-
 	// API 1.21 is the first version that supports docker network commands
 	dockerClient, err := docker.NewVersionedClientFromEnv("1.21")
 	if err != nil {
 		Log.Fatalf("unable to connect to docker: %s", err)
 	}
 
+	if removeNetwork {
+		if _, err = dockerClient.Client.NetworkInfo(meshNetworkName); err == nil {
+			err = dockerClient.Client.RemoveNetwork(meshNetworkName)
+			if err != nil {
+				Log.Fatalf("unable to remove network: %s", err)
+			}
+		}
+		os.Exit(0)
+	}
+
+	Log.Println("Weave plugin", version, "Command line options:", os.Args[1:])
+	Log.Info(dockerClient.Info())
+
 	var globalListener, meshListener net.Listener
 	endChan := make(chan error, 1)
 	if address != "" {

prog/weaver/main.go

@@ -255,6 +255,8 @@ func main() {
 		dc, err := docker.NewClient(dockerAPI)
 		if err != nil {
 			Log.Fatal("Unable to start docker client: ", err)
+		} else {
+			Log.Info(dc.Info())
 		}
 		dockerCli = dc
 	}

proxy/proxy.go

@@ -94,6 +94,8 @@ func NewProxy(c Config) (*Proxy, error) {
 	client, err := weavedocker.NewVersionedClient(c.DockerHost, "1.18")
 	if err != nil {
 		return nil, err
+	} else {
+		Log.Info(client.Info())
 	}
 	p.client = client.Client
 

site/plugin.md

@@ -12,6 +12,12 @@ The Weave Net plugin runs automatically when you `weave launch`.  You
 must still tell the weave peers to connect to one another, either via
 `weave launch` or `weave connect`.
 
+Note that the plugin container (`weaveplugin`) is run with
+`--restart=always`, so that it is there after a restart or reboot. If
+you remove this container (e.g. using `weave reset`) before removing
+all endpoints created using `--net=weave`, Docker can
+[hang](https://github.com/docker/libnetwork/issues/813).
+
 ## Starting a container:
 
     $ docker run --net=weave -ti ubuntu

weave

@@ -1712,7 +1712,14 @@ launch_plugin() {
         $PLUGIN_IMAGE "$@")
 }
 
+remove_plugin_network() {
+    docker run --rm --net=host \
+        -v /var/run/docker.sock:/var/run/docker.sock \
+        $PLUGIN_IMAGE --remove-network
+}
+
 stop_plugin() {
+    remove_plugin_network
     stop $PLUGIN_CONTAINER_NAME "Plugin"
 }
 
@@ -2146,6 +2153,7 @@ EOF
         ;;
     reset)
         [ $# -eq 0 ] || usage
+        remove_plugin_network || echo "WARNING: docker may hang in this state; re-launch weave and remove attached containers before shutting down" >&2
         warn_if_stopping_proxy_in_env
         call_weave DELETE /peer >/dev/null 2>&1 || true
         for NAME in $PLUGIN_CONTAINER_NAME $CONTAINER_NAME $PROXY_CONTAINER_NAME ; do