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.
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
.
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 Mode: REPLICATED Replicas: 1 Placement: UpdateConfig: Parallelism: 1 ContainerSpec: Image: alpine Args: ping docker.com
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": {} } } ]
Run docker service tasks <SERVICE-ID>
to see which nodes are running the service:
$ docker service tasks helloworld ID NAME SERVICE IMAGE LAST STATE DESIRED STATE NODE 8p1vev3fq5zm0mi8g0as41w35 helloworld.1 helloworld alpine Running 3 minutes Running worker2
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.
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
Next, you can change the scale for the service running in the swarm.