Ansible🔗

Automate IT infrastructure with ease

Introduction🔗

Ansible is an automation tool that helps you manage servers, deploy applications, and configure systems. It uses YAML for its playbooks, making it easy to read and write.

Key Features:

Agentless: No software needed on managed nodes.
Idempotent: Running the same playbook multiple times won’t break things.
Declarative: You describe the desired state, and Ansible figures out how to get there.

Installation🔗

Install Ansible on your control machine

sudo apt update  
sudo apt install ansible  

# verify 
ansible --version

Key Concepts🔗

Inventory: A file that lists the servers (nodes) you want to manage.

[webservers]  
web1.example.com  
web2.example.com  

[dbservers]  
db1.example.com

Playbooks: YAML files that define tasks to be executed.

- hosts: webservers  
  tasks:  
    - name: Ensure Apache is installed  
      apt:  
        name: apache2  
        state: present

Modules: Pre-built functions (e.g., apt, copy, service) to perform tasks.
Ad-Hoc Commands: One-liners for quick tasks.

ansible webservers -m ping

Getting Started🔗

Create an Inventory File: Save this as inventory.ini

[webservers]
192.168.1.10
192.168.1.11

[dbservers]  
192.168.1.20

Test Connectivity

ansible all -i inventory.ini -m ping

Write Your First Playbook: Save as webserver.yml

- hosts: webservers  
  become: yes  # Run tasks as root  
  tasks:  
    - name: Install Apache  
      apt:  
        name: apache2  
        state: present  

    - name: Start Apache service  
      service:  
        name: apache2  
        state: started  
        enabled: yes

Run the Playbook

ansible-playbook -i inventory.ini webserver.yml

Common Use Cases🔗

Copy Files🔗

- name: Copy index.html  
  copy:  
    src: files/index.html  
    dest: /var/www/html/index.html

Create Users🔗

- name: Add user 'deploy'  
  user:  
    name: deploy  
    shell: /bin/bash  
    groups: sudo  
    append: yes

Install Packages🔗

- name: Install required packages  
  apt:  
    name:  
      - git  
      - curl  
      - unzip  
    state: present

Restart Services🔗

- name: Restart Nginx  
  service:  
    name: nginx  
    state: restarted

Best Practices🔗

1. Organize Playbooks🔗

Use roles to group related tasks (e.g., webserver, database).
Example structure:

playbooks/  
├── inventory.ini  
├── webserver.yml  
└── roles/  
    └── webserver/  
        ├── tasks/  
        │   └── main.yml  
        ├── handlers/  
        │   └── main.yml  
        └── templates/  
            └── index.html.j2

2. Use Variables🔗

Define variables in group_vars or host_vars

# group_vars/webservers.yml  
http_port: 80

3. Idemptotency🔗

Always check if a task idempotent. For Example

- name: Ensure directory exists  
  file:  
    path: /var/www/html  
    state: directory

4. Error Handling🔗

- block:  
    - name: Try risky task  
      command: /bin/false  
  rescue:  
    - name: Handle failure  
      debug:  
        msg: "Task failed, but we're recovering!"

Troubleshooting🔗

Issue	Solution
"SSH connection failed"	Check SSH keys and `ansible_user` in inventory.
"Permission denied"	Use `become: yes` to run tasks as root.
"Module not found"	Ensure the module is installed (e.g., `apt` for Debian).

Pro Tips🔗

Dry Run: Test Playbooks without making changes

ansible-playbook --check webserver.yml

Tagging Tasks: Run specific tasks using tags

- name: Install Apache  
  apt:  
    name: apache2  
    state: present  
  tags: install

ansible-playbook webserver.yml --tags "install"

Use Vault for Secrets: Encrypt sensitive data

ansible-vault create secrets.yml