Ansible Check if lxd container with name already exists

Question

Is it possible to check in ansible if a container already exists?

I tried the following:

- name: LXD | Check for already existing container
  lxc_container:
    name: {{ container_name }}
    state: absent
  register: check_container_absent

- debug: msg="{{ check_container_absent }}"

- name: LXD | Create dev container
  command: # script to create container #
  when: check_container_absent.exists

But the output of check_container_absent did not change after I created the container.

Another solution would also be to check the location, where the containers are stored, if a folder with the container name exists.

Is there a better solution than to check for the folder?

score 1 · Accepted Answer · answered May 08 '19 at 12:41

According to the official documentation

Containers must have a unique name. If you attempt to create a container with a name that already exists in the users namespace the module will simply return as “unchanged”.

You should be able to check if the container with name container_name exists or doesn't exist respectively by checking if the task reports as changed.

- name: Do container things
  hosts: localhost
  gather_facts: false
  tasks:
  - name: Delete container if exists 
    lxc_container:
      name: {{ container_name }}
      state: absent
    register: delete_container

  - name: Reports false if container did not already exist
    debug:
      var: delete_container.changed

  - name: Create container if not already exists 
    lxc_container:
      name: {{ container_name }}
    register: create_container

  - name: Reports false if container did already exist
    debug:
      var: create_container.changed

Both of the above tasks will actually create/delete the object if it does/does not already exist though.

If you are just looking to collect data on on whether the object exists and conditionally perform some action later depending, you will not want to use the lxc_container module as it is intended to create/delete, not gather information.

Instead you'll probably want to just use the command/shell module with changed_when: false and store the output.

- name: Check whether container exists
  shell: "lxc list | grep -v {{ container_name }}"
  changed_when: false
  ignore_errors: true
  register: lxc_list

- name: Do thing if container does not exist
  debug:
    msg: "It doesn't exist"
  when: lxc_list.rc != 0

I think the second option fits my requirements the best, since the creation of the container is wrapped in a custom bash script. — Pascal, May 08 '19 at 12:50

Ansible Check if lxd container with name already exists

1 Answers1