Reading the log when the service is running (Ansible)

Question

There is a service that performs an update of our system, the execution status can only be viewed in the log or in the service status. The problem is that the execution process takes time, and it will not be possible to just read a static log. How to use Ansible to read a dynamic log before the "Update success" line appears

Answer 1

Regarding

How to use Ansible to read a dynamic log before the "Update success" line appears?

the following approach of Retrying a task until a condition is met and Return Values might work for you.

---
- hosts: test
  become: false
  gather_facts: false

  tasks:

  - name: Check for success
    shell:
      cmd: grep 'Update success' /home/{{ ansible_user }}/service.log
    register: result
    retries: 5
    delay: 5
    until: result.rc == 0

Since grep has a return code of 0 if it find the pattern and a return code of 1 if not, resulting into an output of

PLAY [test] ******************************************
FAILED - RETRYING: Check for success (5 retries left).
FAILED - RETRYING: Check for success (4 retries left).
FAILED - RETRYING: Check for success (3 retries left).

TASK [Check for success] *****************************
changed: [test.example.com]

after writing echo "Update success" >> service.log on the test host.

Further Q&A

• Ansible - Retry task until a file contains a log line
• How to retry Ansible task that may fail?