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user600994
Asked: 2020-11-18 22:45:21 +0800 CST

Using if else statement inside shell module in ansible playbook

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I am trying to run if else statement inside shell module in ansible playbook but looks like my else statement is not executing in any case.

- name:  verify application/database processes are not running
      shell: if ps -eaf | egrep 'apache|http'|grep -v grep > /dev/null echo 'process_running';else echo 'process_not_running';fi
      ignore_errors: false
      register: app_process_check

Please correct me here.

shell ansible ansible-playbook shell-scripting ansible-tower

3 Answers

  1. If you only want to ensure that a service is running you don't need to check it yourself, ansible can handle this for you.

    - name: ensure apache is started
  service:
    name: apache2
    state: started

    Ansible will start it if it is no running, and will do nothing if it already runs.

    If you need to check this for another reason you can do the check in ansible instead of the shell:

    - name: check if apache is running
  shell: ps -eaf
  register: running_processes
  changed_when: >
    ('apache' in running_processes.stdout) or 
    ('httpd' in running_processes.stdout)

    Afterward you can use this with running_processes.changed (or move the check itself to the next task).

    • 3

  2. Fix the if-then-else statement. The keyword then is missing. I've added ps parameter -x to include "processes which do not have a controlling terminal" (which normally web servers do not). The script below works as expected

    #!/bin/sh
if ps -axef | egrep 'apache|http' | grep -v grep > /dev/null; then
    echo 'process_running'
else
    echo 'process_not_running'
fi

    Then use the script in Ansible. You might want to use Literal block scalar to improve the code's readability. For example

        - name:  verify application/database processes are not running
      shell: |
        if ps -axef | egrep 'apache|http' | grep -v grep > /dev/null; then
            echo 'process_running'
        else
            echo 'process_not_running'
        fi
      ignore_errors: false
      register: app_process_check
    - debug:
        var: app_process_check.stdout

    gives, if Apache is running

      app_process_check.stdout: process_running

    otherwise

      app_process_check.stdout: process_not_running
    • 2

  3. Instead of using command:/shell: consider the ansible.builtin.service_facts: module. ansible.docs page for service_facts

    From that page:

    - name: Populate service facts
  service_facts:

- debug:
    var: ansible_facts.services

    From there you can access various facts about configured services.

    ansible_facts.services['httpd'] or ansible_facts.services['apache']

    • 0