grep by design returns code 1 if the given string was not found. Ansible by design stops execution if the return code is different from 0. Your system is working properly.
To prevent Ansible from stopping playbook execution on this error, you can:
ignore_errors: yesparameter to the task
failed_when:parameter with a proper condition
grep returns error code 2 for exceptions, the second method seems more appropriate, so:
- name: Get the http_status shell: grep "http_status=" /var/httpd.txt register: cmdln failed_when: "cmdln.rc == 2" check_mode: no
You might also consider adding
changed_when: false so that the task won’t be reported as “changed” every single time.
All options are described in the Error Handling In Playbooks document.