driver/docker: stopping a dead container not error

drivers/docker/config.go

@@ -20,6 +20,10 @@ const (
 	// does not exist.
 	NoSuchContainerError = "No such container"
 
+	// ContainerNotRunningError is returned by the docker daemon if the container
+	// is not running, yet we requested it to stop
+	ContainerNotRunningError = "Container not running"
+
 	// pluginName is the name of the plugin
 	pluginName = "docker"
 

drivers/docker/handle.go

@@ -148,6 +148,12 @@ func (h *taskHandle) Kill(killTimeout time.Duration, signal os.Signal) error {
 			h.logger.Debug("attempted to stop nonexistent container")
 			return nil
 		}
+		// Container has already been stopped.
+		if strings.Contains(err.Error(), ContainerNotRunningError) {
+			h.logger.Debug("attempted to stop an not-running container")
+			return nil
+		}
+
 		h.logger.Error("failed to stop container", "error", err)
 		return fmt.Errorf("Failed to stop container %s: %s", h.containerID, err)
 	}