Ansible docker connection with identical container names on more than one host

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I'm trying to run an ansible playbook against multiple hosts that are running containers using the same name. There are 3 hosts each running a container called "web". I'm trying to use the docker connection.

I'm using the typical pattern of a hosts file which works fine for running ansible modules on the host.

- name: Ping
  ping:

- name: Add web container to inventory
  add_host:
    name: web
    ansible_connection: docker
    ansible_docker_extra_args: "-H=tcp://{{ ansible_host }}:2375"
    ansible_user: root
  changed_when: false

- name: Remove old logging directory
  delegate_to: web
  file:
    state: absent
    path: /var/log/old_logs

It only works against the first host in the hosts file

PLAY [all]

TASK [Gathering Facts]
ok: [web1]
ok: [web2]
ok: [web3]


TASK [web-playbook : Ping]
ok: [web1]
ok: [web2]
ok: [web3]

TASK [web-playbook : Add sensor container to inventory] 
ok: [web1]

PLAY RECAP 
web1  : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
web2  : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
web3  : ok=4    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

I've tried setting name to web_{{ ansible_host }} to make it unique between hosts but it then tries to connect to web_web1. I've been running the commands using sudo docker exec web rm -rf /var/log/old_logs which of course works, but I'd like to be able to use the ansible modules directly in the docker containers.

ansible
1 Answers

The result you get is absolutely expected. Quoting the add_host documentation

This module bypasses the play host loop and only runs once for all the hosts in the play, if you need it to iterate use a with-loop construct.

i.e. you cannot rely on the hosts loop for the add_host and need to make a loop yourself.

Moreover, you definitely need to have different names (i.e. inventory_hostname) for your dynamically created hosts but since all your docker containers have the same name, their ansible_host should be the same.

Assuming all your docker host machines are in the group dockerhosts, the following playbook should do the job. I'm currently not in a situation where I can test this myself so you may have to adjust a bit. Let me know if it helped you and if I have to edit my answer.

Note that even though the add_host task will not naturally loop, I kept the hosts on your original group in the first play so that facts are gathered correctly and correctly populated in the hostvars magic variable

---
- name: Create dynamic inventory for docker containers
  hosts: dockerhosts

  tasks:
    - name: Add web container to inventory
      add_host:
        name: "web_{{ item }}"
        groups:
          - dockercontainers
        ansible_connection: docker
        ansible_host: web
        ansible_docker_extra_args: "-H=tcp://{{ hostvars[item].ansible_host }}:2375"
        ansible_user: root
      loop: "{{ groups['dockerhosts'] }}"

- name: Play needed commands on containers
  hosts: dockercontainers

  tasks:
    - name: Remove old logging directory
      file:
        state: absent
        path: /var/log/old_logs
user_94010960
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