Inspect a service on the swarm

When you have deployed a service to your swarm, you can use the Docker CLI to see details about the service running in the swarm.

1. If you haven’t already, open a terminal and ssh into the machine where you run your manager node. For example, the tutorial uses a machine named manager1.

2. Run docker service inspect --pretty <SERVICE-ID> to display the details about a service in an easily readable format.

   To see the details on the helloworld service:

   $ docker service inspect --pretty helloworld
   
   ID:		9uk4639qpg7npwf3fn2aasksr
   Name:		helloworld
   Service Mode:	REPLICATED
    Replicas:		1
   Placement:
   UpdateConfig:
    Parallelism:	1
   ContainerSpec:
    Image:		alpine
    Args:	ping docker.com
   Resources:
   Endpoint Mode:  vip
   

   Tip: To return the service details in json format, run the same command without the --pretty flag.

   $ docker service inspect helloworld
   [
   {
       "ID": "9uk4639qpg7npwf3fn2aasksr",
       "Version": {
           "Index": 418
       },
       "CreatedAt": "2016-06-16T21:57:11.622222327Z",
       "UpdatedAt": "2016-06-16T21:57:11.622222327Z",
       "Spec": {
           "Name": "helloworld",
           "TaskTemplate": {
               "ContainerSpec": {
                   "Image": "alpine",
                   "Args": [
                       "ping",
                       "docker.com"
                   ]
               },
               "Resources": {
                   "Limits": {},
                   "Reservations": {}
               },
               "RestartPolicy": {
                   "Condition": "any",
                   "MaxAttempts": 0
               },
               "Placement": {}
           },
           "Mode": {
               "Replicated": {
                   "Replicas": 1
               }
           },
           "UpdateConfig": {
               "Parallelism": 1
           },
           "EndpointSpec": {
               "Mode": "vip"
           }
       },
       "Endpoint": {
           "Spec": {}
       }
   }
   ]
   

3. Run docker service ps <SERVICE-ID> to see which nodes are running the service:

   $ docker service ps helloworld
   
   NAME                                    IMAGE   NODE     DESIRED STATE  LAST STATE
   helloworld.1.8p1vev3fq5zm0mi8g0as41w35  alpine  worker2  Running        Running 3 minutes
   

   In this case, the one instance of the helloworld service is running on the worker2 node. You may see the service running on your manager node. By default, manager nodes in a swarm can execute tasks just like worker nodes.

   Swarm also shows you the DESIRED STATE and LAST STATE of the service task so you can see if tasks are running according to the service definition.

4. Run docker ps on the node where the task is running to see details about the container for the task.

   Tip: If helloworld is running on a node other than your manager node, you must ssh to that node.

   $docker ps
   
   CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
   e609dde94e47        alpine:latest       "ping docker.com"   3 minutes ago       Up 3 minutes                            helloworld.1.8p1vev3fq5zm0mi8g0as41w35
   

What’s next?

Next, you can change the scale for the service running in the swarm.