Refactor is-running check so we can re-use more of the code

common/docker/client.go

@@ -60,16 +60,21 @@ func (c *Client) AddObserver(ob ContainerObserver) error {
 	return nil
 }
 
-// IsContainerRunning returns true if the container is up and running
-func (c *Client) IsContainerRunning(idStr string) (bool, error) {
-	// check with Docker whether the container is really running
-	container, err := c.InspectContainer(idStr)
-	if err != nil {
-		if _, notThere := err.(*docker.NoSuchContainer); notThere {
-			return false, nil
-		}
-		return false, err
+// IsContainerNotRunning returns true if we have checked with Docker that the ID is not running
+func (c *Client) IsContainerNotRunning(idStr string) bool {
+	if !IsContainerID(idStr) {
+		Debug.Printf("[docker] '%s' does not seem to be a container id", idStr)
+		return false
 	}
 
-	return container.State.Running, nil
+	// check with Docker whether the container is really running
+	container, err := c.InspectContainer(idStr)
+	if err == nil {
+		return !container.State.Running
+	}
+	if _, notThere := err.(*docker.NoSuchContainer); notThere {
+		return true
+	}
+	Error.Printf("[docker] Could not check container status: %s", err)
+	return false
 }

nameserver/http.go

@@ -75,18 +75,9 @@ func ServeHTTP(listener net.Listener, version string, server *DNSServer, dockerC
 			} // oh, I already know this. whatever.
 		}
 
-		if dockerCli != nil {
-			if !docker.IsContainerID(idStr) {
-				Debug.Printf("[http] '%s' does not seem to be a container id", idStr)
-				return
-			}
-
-			if running, err := dockerCli.IsContainerRunning(idStr); err != nil {
-				Error.Printf("[http] Could not check container status: %s", err)
-			} else if !running {
-				Info.Printf("[http] '%s' is not running: removing", idStr)
-				server.Zone.DeleteRecords(idStr, name, ip)
-			}
+		if dockerCli != nil && dockerCli.IsContainerNotRunning(idStr) {
+			Info.Printf("[http] '%s' is not running: removing", idStr)
+			server.Zone.DeleteRecords(idStr, name, ip)
 		}
 	})