replace sh ask_version with weaveutil ask-version

prog/weaveutil/main.go

@@ -15,6 +15,7 @@ var commands map[string]func([]string) error
 func init() {
 	commands = map[string]func([]string) error{
 		"help":                     help,
+		"ask-version":              askVersion,
 		"netcheck":                 netcheck,
 		"docker-tls-args":          dockerTLSArgs,
 		"create-bridge":            createBridge,

prog/weaveutil/version.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+
+	docker "github.com/fsouza/go-dockerclient"
+)
+
+func askVersion(args []string) error {
+	if len(args) < 1 {
+		cmdUsage("ask-version", "<container-name-or-id> <image-name-or-id>")
+	}
+	containerID := args[0]
+	imageID := args[1]
+
+	c, err := docker.NewVersionedClientFromEnv("1.18")
+	if err != nil {
+		return fmt.Errorf("unable to connect to docker: %s", err)
+	}
+
+	var image string
+	container, err := c.InspectContainer(containerID)
+	if err != nil {
+		img, err := c.InspectImage(imageID)
+		if err != nil {
+			return fmt.Errorf("unable to find image %s: %s", imageID, err)
+		} else {
+			image = img.ID
+		}
+	} else {
+		image = container.Image
+	}
+
+	//
+	// TODO: Move this code to a helper in container.go for reuse with other `docker run` commands
+	//
+	config := docker.Config{Image: image, Env: []string{"WEAVE_CIDR=none"}, Cmd: []string{"--version"}}
+	hostConfig := docker.HostConfig{AutoRemove: true, NetworkMode: "none"}
+	versionContainer, err := c.CreateContainer(docker.CreateContainerOptions{Config: &config, HostConfig: &hostConfig})
+	if err != nil {
+		return fmt.Errorf("unable to create container: %s", err)
+	}
+
+	err = c.StartContainer(versionContainer.ID, &hostConfig)
+	if err != nil {
+		return fmt.Errorf("unable to start container: %s", err)
+	}
+
+	var buf bytes.Buffer
+	err = c.AttachToContainer(docker.AttachToContainerOptions{Container: versionContainer.ID, OutputStream: &buf, Stdout: true, Stream: true})
+	if err != nil {
+		return fmt.Errorf("unable to attach to container: %s", err)
+	}
+
+	// AutoRemove doesn't work with old Docker daemons (< 1.25), manually remove
+	err = c.RemoveContainer(docker.RemoveContainerOptions{ID: versionContainer.ID, Force: true})
+	if err != nil {
+		return fmt.Errorf("unable to remove container: %s", err)
+	}
+
+	fmt.Print(buf.String())
+	return nil
+}

weave

@@ -560,15 +560,6 @@ router_bridge_opts() {
     [ -z $WEAVE_NO_FASTDP ] || echo --no-fastdp
 }
 
-ask_version() {
-    if check_running $1 2>/dev/null ; then
-        DOCKERIMAGE=$(docker inspect --format='{{.Image}}' $1 )
-    elif ! DOCKERIMAGE=$(docker inspect --format='{{.Id}}' $2 2>/dev/null) ; then
-        echo "Unable to find $2 image." >&2
-    fi
-    [ -n "$DOCKERIMAGE" ] && docker run --rm --net=none -e WEAVE_CIDR=none $3 $DOCKERIMAGE $COVERAGE_ARGS --version
-}
-
 attach() {
     ATTACH_ARGS=""
     [ -n "$NO_MULTICAST_ROUTE" ] && ATTACH_ARGS="--no-multicast-route"
@@ -1339,7 +1330,7 @@ case "$COMMAND" in
         ;;
     version)
         [ $# -eq 0 ] || usage
-        ask_version $CONTAINER_NAME $IMAGE || true
+        util_op ask-version $CONTAINER_NAME $IMAGE || true
         ;;
     attach-bridge)
         if detect_bridge_type ; then