How to make Ansible execute a shell script if a package is not installed

Question

How can I make Ansible execute a shell script if a (rpm) package is not installed? Is it somehow possible to leverage the yum module?

Answer 1

If the package is installable through the system package manager (yum, apt, etc) itself, then you can make use of the check mode flag of ansible to register installation status without actually installing the package.

- name: check if package is installed
  package:
    name: mypackage
    state: present
  check_mode: true
  register: mypackage_check

- name: run script if package installed
  shell: myscript.sh
  when: not mypackage_check.changed