Using Ansible docker_service module to deploy service to swarm

Question

I'm trying to deploy a Docker service into swarm but always ending up with running container on my localhost (the one I use as a docker swarm manager) and no service

Here's my setup:

I have 3 node Docker (v. 1.12.1) swarm that includes one host running as manager and two worker nodes all running on CentOS 7. On the manager node (localhost) I run Ansible (v. 2.1.1.0) playbook and the swarm is already configured and is running

Swarm: active
 NodeID: d9h5xa832ax7wzeq8q44fjld3
 Is Manager: true
 ClusterID: 9cztoin3gy2ntbwehsmrkjuxi
 Managers: 1
 Nodes: 3
 Orchestration:
  Task History Retention Limit: 5
 Raft:
  Snapshot Interval: 10000
  Heartbeat Tick: 1
  Election Tick: 3
 Dispatcher:
  Heartbeat Period: 5 seconds
 CA Configuration:
  Expiry Duration: 3 months
 Node Address: 10.25.190.209

Starting with a playbook that has this code

- hosts: localhost
  name: Run JMeter test
  vars_files:
    - user.config.yml
  vars:
    execute_tpcds_test : "{{ run_tpcds_test }}"    
  roles:
    - { role: run_jmeter, when: execute_tpcds_test is defined and execute_tpcds_test ==1 }

Which calls this role:

- name: Deploy tpcds_tpg service to swarm
  docker_service:
    project_name: tpcds-tpg
    definition:
      version: '2'
      services:
        run_tests: 
          image: 'pbench/tpcds_tpg'
          volumes: 
            - /opt/pbench/run_output/
          command: ./run_jmeter.sh "{{jmeter_output_dir}}" 
  register: output
- debug: var=output

When I run ansible-playbook ./site.yml I end up with a running container. Doing docker ps -a displays

[pdo@sdl02133 tpcds-tpg]$ docker ps -a
CONTAINER ID        IMAGE              COMMAND                  CREATED             STATUS              PORTS               NAMES
fef245b41365        pbench/tpcds_tpg   "./run_jmeter.sh /opt"   21 seconds ago      Up 20 seconds                           tpcdstpg_run_tests_1

And doing docker service ls shows no services running so it looks like docker_service deploys my image as a local container and not as a service on the swarm

So my assumption was that if I have an active swarm on the machine that is a swarm manager and I use Ansible docker_service module, then it will automatically be aware of the swarm and deploy the service to it. Looks like my assumption is wrong and I cannot find any docs, blog posts, etc. that would hint me what to do and what I am missing. Ansible experts please help!

Answer 1

The Ansible module uses Docker Compose which doesn't work with Swarm Mode at the moment. If you run docker-compose on a node in a Swarm, it just issues docker run commands - which is why you have containers running on a single host instead of services running in the Swarm.

You can track swarm mode support in Compose with issue 3656, but when that does happen there may well need to be a change to the Ansible module too (unless Compose is changed to have swarm mode detection logic).