Ansible Playbooks and Roles

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Starting with Ansible Playbooks and Roles for organizing Playbooks

Getting Started with Ansible Playbooks

An Ansible Playbook is a YAML-based script that defines tasks to automate system configurations, deployments, and management. Below is a step-by-step guide to help you get started.

1. Install Ansible

Ensure Ansible is installed on your control machine (For Linux -ubuntu: use the script below).

https://github.com/Devopspat35/ansible-roles/blob/master/bootstrap-ansible.sh

Verify the installation:

ansible --version

2. Set Up the Inventory File

The inventory file (/etc/ansible/hosts or a custom file) defines the managed hosts.

Create an inventory file (inventory.ini):

# ini

[webservers]
192.168.1.10 ansible_user=ubuntu ansible_ssh_private_key_file=~/.ssh/id_rsa
192.168.1.11 ansible_user=ubuntu ansible_ssh_private_key_file=~/.ssh/id_rsa

Test connectivity:

ansible all -m ping -i inventory.ini

Expected Output:

# json

192.168.1.10 | SUCCESS => { "changed": false, "ping": "pong" }
192.168.1.11 | SUCCESS => { "changed": false, "ping": "pong" }

3. Create Your First Playbook

A playbook is a YAML file that defines tasks to execute.

Example: Install and Start Nginx

Create a new file install_nginx.yml:

# yaml

- name: Install and Start Nginx
  hosts: webservers
  become: yes  # Run as sudo
  tasks:
    - name: Install Nginx
      apt:
        name: nginx
        state: present

    - name: Start Nginx service
      service:
        name: nginx
        state: started

4. Run the Playbook

Use the ansible-playbook command:

ansible-playbook -i inventory.ini install_nginx.yml

Expected Output:

# markdown

PLAY [Install and Start Nginx] ****************
TASK [Install Nginx] **************************
changed: [192.168.1.10]
changed: [192.168.1.11]

TASK [Start Nginx service] ********************
ok: [192.168.1.10]
ok: [192.168.1.11]

PLAY RECAP ************************************
192.168.1.10              : ok=2    changed=1  
192.168.1.11              : ok=2    changed=1  

5. Verify the Installation

Check if Nginx is running:

ansible webservers -i inventory.ini -m shell -a "systemctl status nginx"

Alternatively, access it in a browser:

# cpp

http://192.168.1.10

6. Add Handlers for Better Management

Handlers are triggered only when changes occur. Modify install_nginx.yml:

# yaml

- name: Install and Start Nginx
  hosts: webservers
  become: yes
  tasks:
    - name: Install Nginx
      apt:
        name: nginx
        state: present
      notify: Restart Nginx  # Calls handler

    - name: Start Nginx service
      service:
        name: nginx
        state: started

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

Re-run the playbook:

ansible-playbook -i inventory.ini install_nginx.yml

7. Use Variables for Flexibility

Define variables in vars.yml:

# yaml

nginx_package: nginx

Modify the playbook to use variables:

# yaml

- name: Install and Start Nginx
  hosts: webservers
  become: yes
  vars_files:
    - vars.yml
  tasks:
    - name: Install Nginx
      apt:
        name: "{{ nginx_package }}"
        state: present
      notify: Restart Nginx

    - name: Start Nginx service
      service:
        name: "{{ nginx_package }}"
        state: started

  handlers:
    - name: Restart Nginx
      service:
        name: "{{ nginx_package }}"
        state: restarted

Run it:

ansible-playbook -i inventory.ini install_nginx.yml

8. Debugging & Testing

• Check Syntax:

  ansible-playbook install_nginx.yml --syntax-check
  

• Run in Dry Mode:

  ansible-playbook -i inventory.ini install_nginx.yml --check
  

• Enable Verbose Mode:

  ansible-playbook -i inventory.ini install_nginx.yml -vvv
  

 Thoughts:

• Explore roles for organizing playbooks (ansible-galaxy init myrole).
• Use Jinja2 templates for configuration files.
• Integrate Ansible with Docker, Kubernetes, or AWS.
•  

Ansible Roles for Organizing Playbooks

Ansible roles help organize playbooks by breaking them into reusable components. A role is a structured directory that contains tasks, handlers, templates, variables, and other necessary configurations.

1. Why Use Roles?

• Modular & Reusable: Write once, use multiple times.
• Scalability: Manage complex infrastructure easily.
• Separation of Concerns: Keep playbooks clean and manageable.

2. Creating an Ansible Role

You can manually create a role structure or use ansible-galaxy to generate it.

Manual Structure

A role follows this directory structure:

# perl

my-playbook/
├── roles/
│   ├── nginx/
│   │   ├── tasks/        # Contains task files (main.yml)
│   │   ├── handlers/     # Handlers for service restart, etc.
│   │   ├── templates/    # Jinja2 templates for configuration files
│   │   ├── files/        # Static files (e.g., scripts, binaries)
│   │   ├── vars/         # Role-specific variables
│   │   ├── defaults/     # Default variables
│   │   ├── meta/         # Role metadata (dependencies, author)
│   │   ├── tests/        # Testing scripts
│   │   └── README.md     # Documentation
├── inventory.ini
├── site.yml             # Main playbook

Using ansible-galaxy to Generate a Role

Run the following command:

ansible-galaxy init roles/nginx

This creates the necessary directories and files automatically.

3. Writing Role Components

A. Tasks (roles/nginx/tasks/main.yml)

Defines the sequence of actions.

# yaml

- name: Install Nginx
  apt:
    name: nginx
    state: present
  notify: Restart Nginx

- name: Ensure Nginx is running
  service:
    name: nginx
    state: started
    enabled: yes

B. Handlers (roles/nginx/handlers/main.yml)

Executed when notified.

# yaml

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

 C. Variables (roles/nginx/vars/main.yml)

Define custom variables.

# yaml

nginx_port: 80

D. Templates (roles/nginx/templates/nginx.conf.j2)

Jinja2 template for configuration files.

# jinja

server {
    listen {{ nginx_port }};
    server_name localhost;

    location / {
        root /var/www/html;
        index index.html;
    }
}

E. Default Variables (roles/nginx/defaults/main.yml)

Define default values.

# yaml

nginx_port: 80

F. Files (roles/nginx/files/index.html)

Static files (e.g., website content).

4. Using the Role in a Playbook

Create site.yml to apply the role.

# yaml

- name: Configure Web Server
  hosts: webservers
  become: yes
  roles:
    - nginx

Run the playbook:

ansible-playbook -i inventory.ini site.yml

5. Using Role Dependencies

Define dependencies in roles/nginx/meta/main.yml:

# yaml

dependencies:
  - role: common

6. Sharing Roles with Ansible Galaxy

Upload roles for reuse:

ansible-galaxy role install myrole

Insights:

Ansible roles provide a structured way to organize playbooks, making them reusable, scalable, and maintainable.