Ansible Operations¶

Prerequisites¶

• Ansible installed
• SSH key access to target host(s)
• Inventory file configured

Quick Reference¶

Procedure: Preview Changes (Dry Run)¶

When to use: Before applying changes to a live system, preview what Ansible would do without actually making any modifications.

Steps:

1. Run in check mode (dry run — no changes applied):

   ansible-playbook site.yml --check
   

   Tasks will report changed or ok based on what they would do, but nothing is modified on the target.

2. Combine with --diff to see exactly what would change in files:

   ansible-playbook site.yml --check --diff
   

   For template, copy, and lineinfile tasks, this shows a unified diff of the file contents before and after.

3. Use --diff without --check during a real run to see what changed as it happens:

   ansible-playbook site.yml --diff
   

4. Combine with tags to preview a specific role:

   ansible-playbook site.yml --check --diff --tags dns
   

Limitations:

• Some modules cannot predict their result in check mode (e.g., command, shell). These will be skipped.
• Tasks that depend on earlier tasks having actually run may behave differently in check mode.

Procedure: Run a Playbook¶

When to use: Applying configuration to managed hosts.

Steps:

1. Syntax check:

   ansible-playbook --syntax-check site.yml
   

2. Run the playbook:

   ansible-playbook -i inventory.ini site.yml
   

3. Run with sudo/become prompt (if password needed):

   ansible-playbook -i inventory.ini site.yml -K
   

Troubleshooting:

• "Unreachable": Check SSH connectivity and key setup.
• "Permission denied": Ensure the user has sudo rights and you used -b (become) in the playbook or command.

Procedure: Run with Tags¶

When to use: Running only specific parts of a playbook (e.g., only updating configuration files).

Steps:

1. List available tags:

   ansible-playbook site.yml --list-tags
   

2. Run specific tags:

   ansible-playbook site.yml --tags "nginx,config"
   

3. Skip tags:

   ansible-playbook site.yml --skip-tags "packages"
   

Troubleshooting:

• "No tasks run": The tags might be misspelled or applied to tasks that didn't need to run (idempotency).

Procedure: Create a Role¶

When to use: Structuring complex configurations into reusable components.

Steps:

1. Initialize role structure:

   ansible-galaxy init roles/myrole
   

2. Structure:

   • tasks/main.yml: Main list of tasks
   • handlers/main.yml: Service restarts
   • templates/: Jinja2 configuration templates
   • vars/main.yml: Role-specific variables

Troubleshooting:

• Role not found: Ensure roles_path is configured in ansible.cfg or the role is in a roles/ directory relative to the playbook.

Procedure: Use Variables¶

When to use: Making playbooks flexible (e.g., different ports for dev/prod).

Steps:

1. Define in group_vars/all.yml:

   http_port: 80
   

2. Use in tasks:

   - name: Start Apache
     service:
       name: "{{ apache_service }}"
       state: started
   

3. Use in templates (.j2):

   Listen {{ http_port }}
   

Troubleshooting:

• "Undefined variable": Check variable scope and precedence.

Procedure: Use Handlers¶

When to use: Restarting a service only when a configuration file changes.

Steps:

1. Define handler:

   handlers:
     - name: restart apache
       service:
         name: httpd
         state: restarted
   

2. Notify from task:

   - name: Copy config
     template:
       src: httpd.conf.j2
       dest: /etc/httpd/conf/httpd.conf
     notify: restart apache
   

Troubleshooting:

• Handler didn't run: The notify task must report "changed". If the file was already correct, the handler won't trigger.

Procedure: Push to GitLab¶

When to use: Saving your Ansible code to version control.

Steps:

1. Check status:

   git status
   

2. Add changes:

   git add .
   

3. Commit:

   git commit -m "Update apache role configuration"
   

4. Push:

   git push origin main
   

Troubleshooting:

• "rejected": Pull changes from remote first (git pull).

Related Documentation¶

• Technologies: Ansible
• Concepts: Configuration Management, Version Control