How can I replace a value of dictionary based on a key condition in values.yaml via Ansible playbook?

Question

I have a values.yaml file and I want to update the particular value of a dictionary based on its key.

For Example

input.yaml

env:
- name: "namespace1"
  value: "abc"
- name: "namespace2"
  value: "ijk"

Expected Result to be updated in the same input.yaml

env:
- name: "namespace1"
  value: "xyz"
- name: "namespace2"
  value: "ijk"

only if the key is namespace1, its value should be as xyz from abc

Updated input.yaml

operator:
  operator:
    replicaCount: 1
    env:
      - name: namespace1
        value: abc
    resources:
      requests:
        cpu: 200m
        memory: 256Mi
        ephemeral-storage: 500Mi
  console:
    replicaCount: 1

Answer 1

Here is a self explanatory playbook with intermediate step debugging

Example file structure:

$ tree
.
├── input.yml
└── test.yml

0 directories, 2 files

input.yaml before running playbook

env:
-   name: namespace1
    value: abc
-   name: namespace2
    value: ijk

test.yml playbook:

---
- name: Make sure var file contains what we expect
  hosts: localhost
  gather_facts: false

  vars:
    inputf: input.yml
    env_as_dict: "{{ env | items2dict(key_name='name') }}"
    env_as_dict_transformed: "{{ env_as_dict | combine({'namespace1': 'xyz'}) }}"
    env_as_transformed_list: "{{ env_as_dict_transformed | dict2items(key_name='name') }}"

  vars_files:
    - "{{ inputf }}"

  tasks:
    - name: Convert original env var from a list of key/value pairs to a dict
      ansible.builtin.debug:
        var: env_as_dict

    - name: Combine resulting dict with expected value
      ansible.builtin.debug:
        var: env_as_dict_transformed

    - name: Convert the transformed dict back to a list
      ansible.builtin.debug:
        var: env_as_transformed_list

    - name: Write the content back to original file
      # Note: this works because we target localhost only
      # `delegate_to: localhost` and `run_once: true`
      # for a play targeting multiple non local hosts.
      vars:
        fcontent:
          env: "{{ env_as_transformed_list }}"
      ansible.builtin.copy:
        dest: "{{ inputf }}"
        content: "{{ fcontent | to_nice_yaml }}"

which gives as a result

$ ansible-playbook test.yml 

PLAY [Make sure var file contains what we expect] ***********************************************************************************

TASK [Convert original env var from a list of key/value pairs to a dict] ************************************************************
ok: [localhost] => {
    "env_as_dict": {
        "namespace1": "abc",
        "namespace2": "ijk"
    }
}

TASK [Combine resulting dict with expected value] ***********************************************************************************
ok: [localhost] => {
    "env_as_dict_transformed": {
        "namespace1": "xyz",
        "namespace2": "ijk"
    }
}

TASK [Convert the transformed dict back to a list] **********************************************************************************
ok: [localhost] => {
    "env_as_transformed_list": [
        {
            "name": "namespace1",
            "value": "xyz"
        },
        {
            "name": "namespace2",
            "value": "ijk"
        }
    ]
}

TASK [Write the content back to original file] **************************************************************************************
changed: [localhost]

PLAY RECAP **************************************************************************************************************************
localhost                  : ok=4    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

And the content of input.yml after running the playbook is

env:
-   name: namespace1
    value: xyz
-   name: namespace2
    value: ijk

Note that running the playbook again will report OK on the last task as the content of the file will already be aligned with what is expected.