Ansible Systemd Module Examples: A Beginner’s Guide

Managing services on Linux is a core task for system administrators. Ansible makes this easier with its systemd module. It allows you to automate tasks like starting, stopping, restarting, enabling, and disabling services remotely. This module is especially useful for system administrators who need to handle service management across multiple servers.

In this comprehensive guide, we’ll dive deep into the Ansible systemd module with practical and real-world examples.

What is the Ansible Systemd Module?

The Ansible systemd module is specifically designed for managing services on Linux systems that use the systemd service manager. It allows you to control service states across multiple hosts with minimal effort.

The basic syntax of the systemd module includes key parameters like name, state, enabled, and daemon_reload:

- name: Manage a systemd service
  ansible.builtin.systemd:
    name: service_name
    state: started/stopped/restarted
    enabled: yes/no
    daemon_reload: yes/no

Example 1: Start a Service

Starting a service is a common administrative task. With Ansible, you can automate it easily. Here’s a playbook to start the nginx service:

- hosts: web
  become: true
  tasks:
    - name: Start nginx service
      ansible.builtin.systemd:
        name: nginx
        state: started

Here is the explanation:

• become: true is used to run the task with root privileges.
• state: started ensures the service is running. If it’s not, Ansible will start it.

Example 2: Stop and Disable a Service

Stopping a service can help conserve resources or improve security. Disabling a service ensures it doesn’t start automatically on boot.

Here is an example playbook that stops and disables the Apache service on the remote node.

- hosts: web
  become: true
  tasks:
    - name: Stop and disable apache2 service
      ansible.builtin.systemd:
        name: apache2
        state: stopped
        enabled: no

In this playbook:

• state: stopped halts the service if it is currently running.
• enabled: no prevents the service from starting automatically on system boot.

Example 3: Restart a Service

Restarting a service is necessary after applying configuration changes. Here is an example playbook that automates this:

- hosts: web
  become: true
  tasks:
    - name: Restart ssh service
      ansible.builtin.systemd:
        name: ssh
        state: restarted

In the above playbook:

• state: restarted stops and then starts the service, ensuring it runs with the latest configuration.

Example 4: Enable a Service at Boot

Enabling a service ensures it starts automatically when the system boots. Here’s how to enable MySQL on a remote host:

- hosts: web
  become: true
  tasks:
    - name: Enable mysql service at boot
      ansible.builtin.systemd:
        name: mysql
        enabled: yes

In this playbook:

• enabled: yes ensures the service starts during system boot.

Example 5: Using daemon_reload

When you create or modify a service unit file, you need to reload the systemd daemon. Here’s an example playbook:

- hosts: web
  become: true
  tasks:
    - name: Reload systemd daemon
      ansible.builtin.systemd:
        daemon_reload: true

    - name: Restart custom service
      ansible.builtin.systemd:
        name: custom-service
        state: restarted

In the above playbook:

• daemon_reload: true reloads the systemd manager configuration.
• state: restarted ensures the service runs with the updated unit file.

Example 6: Conditional Execution

You can conditionally execute tasks based on specific conditions. Here’s an example playbook that restarts Nginx only if the configuration file is updated:

- hosts: web
  become: true
  tasks:
    - name: Restart nginx only if the configuration file is updated
      ansible.builtin.systemd:
        name: nginx
        state: restarted
      when: nginx_config_changed

Here’s an explanation:

• when: nginx_config_changed runs the task only if the variable nginx_config_changed is true.

Example 7: Using Ansible Loops

You can use a loop with systemd module to manage multiple services remotely. The below playbook restarts Nginx, MySQL and PHP-FPM services:

- hosts: web
  become: true
  tasks:
    - name: Restart multiple services
      ansible.builtin.systemd:
        name: "{{ item }}"
        state: restarted
      loop:
        - nginx
        - mysql
        - php-fpm

In this playbook:

• The loop keyword iterates over a list of services, applying the same action to each.

Conclusion

In this article, we covered the Ansible systemd module with practical examples. You learned how to start, stop, restart, enable services, and use advanced features like conditional execution and daemon reload. Try these examples in your environment to automate service management effectively.

For further reading, check out related Ansible modules like the command and service modules.

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