Ansible loop to create docker networks - docker-compose

Question

Suppose I have my docker networks defined in a variable such as:
docker_networks:
- name: default
driver: bridge
- name: proxy
driver: bridge
ipam_options:
subnet: '192.168.100.0/24'
- name: socket_proxy
driver: bridge
ipam_options:
subnet: '192.168.101.0/24'
How would I go about running this with a loop to create these docker networks?
I tried the following, however the ipam_config parameter causes it to fail if no subnet is defined:
- name: Create networks
docker_network:
name: '{{ item.name }}'
driver: '{{ item.driver | default(omit) }}'
ipam_config:
- subnet: '{{ item.ipam_options.subnet | default(omit) }}'
loop: '{{ docker_networks }}'

Answer 1

If you modify your docker_networks variable so that the value of the ipam_options key is a list of dictionaries:
docker_networks:
- name: proxy
driver: bridge
ipam_options:
- subnet: '192.168.100.0/24'
- name: socket_proxy
driver: bridge
ipam_options:
- subnet: '192.168.101.0/24'
- name: no_subnet
driver: bridge
Then you can rewrite your task like this:
- name: Create networks
community.docker.docker_network:
name: '{{ item.name }}'
driver: '{{ item.driver | default(omit) }}'
ipam_config: "{{ item.ipam_options | default(omit) }}"
loop: '{{ docker_networks }}'
(I would also just rename the ipam_options key to ipam_config, so
that it matches the parameter name.)