Ansible Handlers Explained: How to Use and Flush Handlers — Video Tutorial

When do Ansible Handlers run? > By default, handlers run after all the tasks in a particular play have been completed. Links - https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_handlers.html#controlling-when-handlers-run Demo Let's jump into a real-life example of how to run an Ansible Handler immediately. First of all, we need a task changed status. The simplest Ansible module returning a "changed" status is Ansible `command` module with a Linux command, like "uptime". Let's suppose we would like to execute a handler immediately after the changed status and not wait for the next task using the `ansible.builtin.meta` module. Initial Playbook - flush_before.yml ```yaml --- - name: handler Playbook hosts: all tasks: - name: changed status ansible.builtin.command: "uptime" notify: message 1 - name: message 2 ansible.builtin.debug: msg: message 2 handlers: - name: message 1 ansible.builtin.debug: msg: message 1 ``` inventory ```ini localhost ansible_connection=local ``` Initial Execution As you can notice the `message 1` handler is executed AFTER the last task (`message 2`) of the Play being executed. ```bash $ ansible-playbook -i inventory flush_before.yml PLAY [handler Playbook] ********************************************************************* TASK [Gathering Facts] ****************************************************************** ok: [localhost] TASK [changed status] ******************************************************************* changed: [localhost] TASK [message 2] ************************************************************************ ok: [localhost] => { "msg": "message 2" } RUNNING HANDLER [message 1] ************************************************************* ok: [localhost] => { "msg": "message 1" } PLAY RECAP ****************************************************************************** localhost : ok=4 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0 ``` Modified Playbook Let's add the `ansible.builtin.meta` Ansible module after the first task. ```yaml --- - name: handler Playbook hosts: all tasks: - name: changed status ansible.builtin.command: "uptime" notify: message 1 - name: flush ansible.builtin.meta: flush_handlers - name: message 2 ansible.builtin.debug: msg: message 2 handlers: - name: message 1 ansible.builtin.debug: msg: message 1 ``` Modified Execution As you can notice the `message 1` handler is executed BEFORE the last task (`message 2`) of the Play being executed. ```bash % ansible-playbook -i inventory flush.yml PLAY [handler Playbook] ********************************************************************* TASK [Gathering Facts] ****************************************************************** ok: [localhost] TASK [changed status] ***********************************************