How do I add a custom message if a task does not meet the 'when' condition and is skipped?

In this task, I am searching for a file. If there is no file, the task will be skipped. My question is, how do I write a custom message to output when the task is skipped?

- name: Search for files 
  win_find:
    paths: C:\dataset\
  register: data

- debug:
    msg: "Data exists"
  when: data | json_query('files[*].exists')

- name: set_fact
  set_fact:
    exists: "{{ data | json_query('files[*].exists') }}"

In a different playbook:

- name: Run if file exists
  block:
    - name: read content from file
      win_shell: C:\day.txt  
      register: day
  when: hostvars['10.11.18.190']['exists']

- name: print message
  debug:
    msg: "{{ hostvars['10.12.201.20']['day'] }}"

As there is no file, the task is skipped:

TASK [Run if file exists] *********************
skipping: [10.11.18.190] => {
    "changed": false,
    "skip_reason": "Conditional result was False"
}

TASK [print message] **************************************************************************************
ok: [10.11.18.190] => {
    "msg": {
        "changed": false,
        "skip_reason": "Conditional result was False",
        "skipped": true
    }
}

As you can see from the output, the variable hostvars['10.12.201.20']['day'] is showing "changed": false, skip_reason, etc. But I do not want this, I want it to output a message like, "File does not exist".

How can I create a custom message for this variable hostvars['10.12.201.20']['day']?

Solution

A: Use the 'Do It Yourself' callback plugin community.general.diy. See

shell> ansible-doc -t callback community.general.diy

(or the online documentation)

For example, if the file /tmp/day.txt does not exist the playbook

shell> cat pb.yml
- hosts: localhost
  tasks:
    - stat:
        path: /tmp/day.txt
      register: stat_day
    - command: cat /tmp/day.txt
      register: day
      when: stat_day.stat.exists
      vars:
        ansible_callback_diy_runner_on_skipped_msg: |
          skipping: [{{ inventory_hostname }}]
          msg: File does not exist.
        ansible_callback_diy_runner_on_skipped_msg_color: green

will display the custom message

^{shell> ANSIBLE_STDOUT_CALLBACK=community.general.diy ansible-playbook pb.yml

PLAY [localhost] *****************************************************************************

TASK [stat] **********************************************************************************
ok: [localhost]

TASK [command] *******************************************************************************
skipping: [localhost]
msg: File does not exist.

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

Optionally, you can use the block/rescue construct. See Handling errors with blocks.

For example, in Linux (I don't have access to Windows atm) when you try to access a nonexistent file by the module command on the localhost

    - command: cat /tmp/day.txt
      register: day

the command will fail

fatal: [localhost]: FAILED! => changed=true 
  ansible_facts:
    discovered_interpreter_python: /usr/bin/python3
  cmd:
  - cat
  - /tmp/day.txt
  delta: '0:00:00.010884'
  end: '2023-02-14 07:21:50.664051'
  msg: non-zero return code
  rc: 1
  start: '2023-02-14 07:21:50.653167'
  stderr: 'cat: /tmp/day.txt: No such file or directory'
  stderr_lines: <omitted>
  stdout: ''
  stdout_lines: <omitted>

Put the command into the block and use the section rescue

    - block:
        - command: cat /tmp/day.txt
          register: day
        - debug:
            var: day.stdout
      rescue:
        - debug:
            var: ansible_failed_result

Now, if the command fails you'll see

  ansible_failed_result:
    ansible_facts:
      discovered_interpreter_python: /usr/bin/python3
    changed: true
    cmd:
    - cat
    - /tmp/day.txt
    delta: '0:00:01.007972'
    end: '2023-02-14 07:24:43.791343'
    failed: true
    invocation:
      module_args:
        _raw_params: cat /tmp/day.txt
        _uses_shell: false
        argv: null
        chdir: null
        creates: null
        executable: null
        removes: null
        stdin: null
        stdin_add_newline: true
        strip_empty_ends: true
    msg: non-zero return code
    rc: 1
    start: '2023-02-14 07:24:42.783371'
    stderr: 'cat: /tmp/day.txt: No such file or directory'
    stderr_lines:
    - 'cat: /tmp/day.txt: No such file or directory'
    stdout: ''
    stdout_lines: []

You can reduce the output to the standard error

      rescue:
        - debug:
            var: ansible_failed_result.stderr

If the file exists

shell> echo 'This is the content of /tmp/day.txt' > /tmp/day.txt

The next task in the block will display the standard output of the command

  day.stdout: This is the content of /tmp/day.txt

Of course, there will be differences in the error messages among the operating systems. Take a look at the data you get and fit the messages to your needs.