Check if service exists with Ansible

Question

I have an Ansible playbook for deploying a Java app as an init.d daemon.

Being a beginner in both Ansible and Linux I'm having trouble to conditionally execute tasks on a host based on the host's status.

Namely I have some hosts having the service already present and running where I want to stop it before doing anything else. And then there might be new hosts, which don't have the service yet. So I can't simply use service: name={{service_name}} state=stopped, because this will fail on new hosts.

How I can I achieve this? Here's what I have so far:

  - name: Check if Service Exists     shell: "if chkconfig --list | grep -q my_service;   then echo true;   else echo false; fi;"     register: service_exists  # This should only execute on hosts where the service is present   - name: Stop Service     service: name={{service_name}} state=stopped     when: service_exists     register: service_stopped  # This too   - name: Remove Old App Folder     command: rm -rf {{app_target_folder}}     when: service_exists  # This should be executed on all hosts, but only after the service has stopped, if it was present   - name: Unpack App Archive     unarchive: src=../target/{{app_tar_name}} dest=/opt 

Answer 1

See the service_facts module, new in Ansible 2.5.

- name: Populate service facts   service_facts: - debug:     msg: Docker installed!   when: "'docker' in services" 

Answer 2

Of course I could also just check if the wrapper script exists in /etc/init.d. So this is what I ended up with:

  - name: Check if Service Exists     stat: path=/etc/init.d/{{service_name}}     register: service_status    - name: Stop Service     service: name={{service_name}} state=stopped     when: service_status.stat.exists     register: service_stopped