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:

    [manager1]$ 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.

    [manager1]$ 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:

    [manager1]$ docker service ps helloworld  NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS 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 CURRENT 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.

    [worker2]$ 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

Next steps

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

Change the scale