Is there is the way to skip ansible list parameter if provided list is empty?

Question

I'm trying to use ansible to run docker, one of parameters is ports which is a list. Is there a way to NOT SET IT UP if provided list is empty? I know that I can separate it based on when parameter, but my target is to have single common step for that: default(omit) works for dictionary, not for list

- name: Redeploy {{ service.name }} container
  docker_container:
      name: "{{ sservice.name }}"
      image: "{{ service.image['name'] }}:{{ service.image['version'] }}"
      state: stopped
      networks:
        - name: "{{ docker_network }}"
      env: "{{ sservice.config['environment'] | default(omit) }}"
      ports: "{{ service.config['ports'] | default(omit) }}"
      log_driver: "json-file"
      log_options:
          max-size: "10m"
      pull: false
      recreate: yes
      restart_policy: always

kingkong · Answer

My problem was that in my configuration I was passing an empty list to docker_container module what leaded to en error FAILED! => {"changed": false, "msg": "Invalid port: \"\""}

When ports is not set, the value is omitted as expected. Kudos to @Zeitounator !

userkKBh1 · Answer

You can add a when conditional to the task with the jinja2 filter count/length :

when: service.config['ports'] | count > 0

Is there is the way to skip ansible list parameter if provided list is empty?

2 Answers