Introduction

Ansible is a powerful open-source automation tool that simplifies the configuration management, application deployment, and task automation processes. This cheat sheet provides a quick reference to commonly used Ansible commands and concepts, accompanied by real-time use cases to illustrate their practical application.

Ansible Cheat Sheet

1. Inventory Management

• Command:ansible-inventory

• Use Case: List all hosts in the inventory.

•     ansible-inventory --list
  

2. Ad-hoc Commands

• Command:ansible

• Use Case: Run a command on all hosts in the inventory.

•     ansible all -m command -a "uptime"
  

3. Playbooks

• Command:ansible-playbook

• Use Case: Execute a playbook.

•     ansible-playbook deploy-app.yaml
  

4. Variables

• Command:{{ variable_name }}

• Use Case: Use a variable in a playbook.

•     tasks:
        - name: Ensure package is installed
          apt:
            name: "{{ package_name }}"
            state: present
  

5. Loops

• Command:with_items

• Use Case: Iterate over a list in a playbook.

•     tasks:
        - name: Create users
          user:
            name: "{{ item }}"
            state: present
          with_items:
            - user1
            - user2
  

6. Conditionals

• Command:when

• Use Case: Add a condition to a task.

•     tasks:
        - name: Restart Apache if config file changes
          service:
            name: apache2
            state: restarted
          when: "'apache.conf' in ansible.builtin.changed_files"
  

7. Roles

• Command:ansible-galaxy

• Use Case: Create a new role.

•     ansible-galaxy init my-role
  

8. Vault

• Command:ansible-vault

• Use Case: Encrypt sensitive data.

•     ansible-vault encrypt secrets.yaml
  

Real-Time Use Cases

1. Deploying a Web Application:

   • Use Ansible to deploy a web application on multiple servers, ensuring consistency and scalability.

2. Configuring Monitoring Agents:

   • Automate the installation and configuration of monitoring agents on servers using Ansible playbooks.

3. Scaling Infrastructure:

   • Dynamically scale your infrastructure by adding or removing servers based on demand using Ansible.

4. Continuous Integration/Continuous Deployment (CI/CD):

   • Integrate Ansible into your CI/CD pipeline to automate deployment tasks and ensure efficient release management.

5. Database Configuration:

   • Use Ansible to automate the setup and configuration of databases, ensuring a standardized environment.

6. Security Patching:

   • Implement Ansible to automate the process of applying security patches across multiple servers simultaneously.

9. Dynamic Inventory

• Command:ansible-inventory --graph

• Use Case: Display the inventory structure in a graph.

•     ansible-inventory --graph
  

10. Handlers

• Command:handlers

• Use Case: Define a handler to restart a service only if a task triggers it.

•     handlers:
        - name: restart apache
          service:
            name: apache2
            state: restarted
  

11. Tags

• Command:--tags and --skip-tags

• Use Case: Run specific tasks or skip others based on tags.

•     ansible-playbook deploy-app.yaml --tags "install,config"
  

12. Ansible Vault Encryption and Decryption

• Command:ansible-vault encrypt_string

• Use Case: Encrypt sensitive strings for use in playbooks.

•     ansible-vault encrypt_string 'secret_password' --name 'db_password'
  

13. Custom Modules

• Command:ansible-doc -l | grep your_module

• Use Case: Develop and use custom Ansible modules.

•     ansible-doc -l | grep custom_module
  

14. Jinja2 Templating

• Command:{{ variable | filter }}

• Use Case: Use Jinja2 filters for dynamic content.

•     tasks:
        - name: Set dynamic variable
          set_fact:
            dynamic_value: "{{ base_value | upper }}"
  

15. Notify and Wait for Completion

• Command:async and poll

• Use Case: Execute tasks asynchronously and wait for their completion.

•     tasks:
        - name: Long-running task
          command: /path/to/long_running_script.sh
          async: 300
          poll: 0
          register: job_result
  
        - name: Wait for completion
          async_status:
            jid: "{{ job_result.ansible_job_id }}"
          until: job_result.finished
          retries: 30
  

Real-Time Use Cases (Continued)

1. Automated Backup Strategy:

   • Utilize Ansible to create an automated backup strategy, including regular backups and cleanup tasks.

2. Multi-Environment Deployment:

   • Manage deployments across multiple environments (e.g., development, staging, production) using dynamic inventories and environment-specific playbooks.

3. Infrastructure Monitoring Setup:

   • Automate the deployment of monitoring tools and configurations across servers to ensure real-time visibility into infrastructure health.

4. Custom Module for Application-specific Tasks:

   • Develop a custom Ansible module to handle application-specific tasks, providing flexibility in automation.

5. Rolling Updates:

   • Implement rolling updates for services, ensuring zero downtime during updates by using Ansible's serial and max_fail_percentage features.

6. Git Repository Management:

   • Automate tasks related to Git repositories, such as cloning, pulling updates, and managing branches.