Merge pull request #1886 from weaveworks/issues/1869-leave-plugin

Allow plugin to keep running on 'weave launch'

weave

@@ -909,22 +909,22 @@ check_not_running() {
     case ${RUN_STATUS%:*} in
         "true restarting $3")
             echo "$2 is restarting; you can stop it with 'weave stop-$1'." >&2
-            exit 1
+            return 3
             ;;
         "true "*" $3")
             echo "$2 is already running; you can stop it with 'weave stop-$1'." >&2
-            exit 1
+            return 1
             ;;
         "false "*" $3")
             docker rm $2 >/dev/null
             ;;
         true*)
             echo "Found another running container named '$2'. Aborting." >&2
-            exit 1
+            return 2
             ;;
         false*)
             echo "Found another container named '$2'. Aborting." >&2
-            exit 1
+            return 2
             ;;
     esac
 }
@@ -1689,7 +1689,14 @@ stop_proxy() {
     stop $PROXY_CONTAINER_NAME "Proxy"
 }
 
-launch_plugin() {
+launch_plugin_if_not_running() {
+    retval=0
+    check_not_running plugin $PLUGIN_CONTAINER_NAME $BASE_PLUGIN_IMAGE || retval=$?
+    # If an existing plugin is running (we start it with restart=always), return its ID
+    [ $retval = 1 ] && PLUGIN_CONTAINER=$(container_id $PLUGIN_CONTAINER_NAME) && return 0
+    # Any other kind of error code from check_not_running is a failure.
+    [ $retval -gt 0 ] && return $retval
+
     PLUGIN_CONTAINER=$(docker run --privileged -d --name=$PLUGIN_CONTAINER_NAME \
         --restart=always \
         --net=host \
@@ -1846,11 +1853,11 @@ EOF
         deprecation_warnings "$@"
         check_not_running router $CONTAINER_NAME        $BASE_IMAGE
         check_not_running proxy  $PROXY_CONTAINER_NAME  $BASE_EXEC_IMAGE
-        check_not_running plugin $PLUGIN_CONTAINER_NAME $BASE_PLUGIN_IMAGE
+        # Don't check the plugin here, since we start it with `--restart=always`
         COMMON_ARGS=$(common_launch_args "$@")
         launch_router "$@"
         launch_proxy  $COMMON_ARGS
-        plugin_disabled || launch_plugin $COMMON_ARGS
+        plugin_disabled || launch_plugin_if_not_running $COMMON_ARGS
         ;;
     launch-router)
         deprecation_warnings "$@"
@@ -1873,8 +1880,7 @@ EOF
         echo $PROXY_CONTAINER
         ;;
     launch-plugin)
-        check_not_running plugin $PLUGIN_CONTAINER_NAME $BASE_PLUGIN_IMAGE
-        launch_plugin "$@"
+        launch_plugin_if_not_running "$@"
         echo $PLUGIN_CONTAINER
         ;;
     env|proxy-env)