Ansible jinja2 templating - templates

Question

In Ansible, I currently have vars set out like this
container_a_version: 1
container_b_version: 6
container_c_version: 3
container_d_version: 2
...
containers:
- container_a
- container_b
- container_c
- container_d
...
Each container has its own template file which has a line like this
image: registry.sportpesa.com/sportpesa/global/container-a:{{ container_a_version }}
My playbook
- name: Copy templates
template:
src: templates/docker-compose-{{ item }}.yml
dest: /srv/docker-compose-{{ item }}.yml
loop: "{{ containers }}"
If I want to deploy only container a and c. I change my variable to this
containers:
- container_a
# - container_b
- container_c
# - container_d
What I want to do condense my variables to just have 1 var like this
containers:
- { name: a, version: 1 }
- { name: b, version: 6 }
- { name: c, version: 3 }
- { name: d, version: 2 }
However I'm not sure how I can call the container version in my template. Is this possible?

Answer 1

For example, the playbook
shell> cat pb.yml
- hosts: localhost
vars:
containers:
- {name: a, version: 1}
- {name: b, version: 2}
tasks:
- template:
src: containers.txt.j2
dest: containers.txt
and the template
shell> cat containers.txt.j2
{% for item in containers %}
name: {{ item.name }} version {{ item.version }}
{% endfor %}
give
shell> cat containers.txt
name: a version 1
name: b version 2
It's possible to iterate the list
- debug:
msg: "image: registry.example.com/container-{{ item.name }}:container_{{ item.version }}_version"
loop: "{{ containers }}"
gives
msg: 'image: registry.example.com/container-a:container_1_version'
msg: 'image: registry.example.com/container-b:container_2_version'

Answer 2

Since you want two different templates, each with it's respective container name and version without looping the containers variable. You can use a playbook that renders two templates. In my example I will call the templates:
container-a
container-b
The template container-a.j2:
image: registry.example.com/container-{{ containers[0]['name'] }}:{{ containers[0]['version'] }}
The template container-b.j2:
image: registry.example.com/container-{{ containers[1]['name'] }}:{{ containers[1]['version'] }}
Then my playbook will have below tasks:
vars:
containers:
- { name: a, version: 1 }
- { name: b, version: 2 }
tasks:
- template:
src: "container-{{ containers[0]['name'] }}.j2"
dest: "/tmp/container-{{ containers[0]['name'] }}"
- template:
src: "container-{{ containers[1]['name'] }}.j2"
dest: "/tmp/container-{{ containers[1]['name'] }}"
When this playbook is run, it renders /tmp/container-a:
image: registry.example.com/container-a:1
and /tmp/container-b:
image: registry.example.com/container-b:2