Prepend string to list item and turn it into JSON in Ansible

You can do this like so:

---- hosts: localhost  connection: local  gather_facts: no  vars:    ports:      - 123      - 456  tasks:    - name: Creating custom ports      set_fact:        container_ports: '{{ ports | map("regex_replace", "^(.*)$", "containerPort: \1") | map("from_yaml") | list }}'    - debug:        var: container_ports...

The trick is to convert each item into a YAML hash and then convert that to a Python dict using from_yaml.

Debug output:

ok: [localhost] => {    "container_ports": [        {            "containerPort": 123        },         {            "containerPort": 456        }    ]}

An other solution using json_query

---- hosts: localhost  gather_facts: false  vars:    ports:      - 123      - 456  tasks:    - name: Tranform raw list to Kubernetes compatible format      debug:        msg: "{{ ports | json_query('[].{\"containerPort\": @}') }}"

Which gives:

PLAY [localhost] ***********************************************************************************************************************************************************************************************************************TASK [Tranform raw list to Kubernetes compatible format] *******************************************************************************************************************************************************************************ok: [localhost] => {    "msg": [        {            "containerPort": 123        },        {            "containerPort": 456        }    ]}PLAY RECAP *****************************************************************************************************************************************************************************************************************************localhost                  : ok=1    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0