Ansible is an open-source automation tool used for configuration management, application deployment, and task automation. It is designed to automate IT processes and help organizations manage complex IT environments with ease. Ansible uses a simple, human-readable language (YAML) to describe automation jobs, which makes it accessible for beginners and powerful for experts.

Key Features of Ansible:

1. Agentless: No need to install any software or agent on the client systems.
2. Simple YAML Syntax: Uses YAML (Yet Another Markup Language) for writing playbooks.
3. Idempotency: Ensures that changes are only applied when necessary, avoiding repeated tasks.
4. Extensible: Supports modules for various types of tasks (e.g., cloud provisioning, configuration management, application deployment).

Business Use Cases for Ansible:

1. Configuration Management: Ensuring all servers are configured consistently.
   • Example: Setting up and maintaining consistent configurations across web servers, databases, and application servers.
2. Application Deployment: Automating the deployment of applications across multiple servers.
   • Example: Deploying a web application to multiple environments (development, staging, production).
3. Provisioning: Automating the creation of cloud instances and configuring them.
   • Example: Creating and configuring AWS EC2 instances with predefined configurations.
4. Continuous Integration/Continuous Deployment (CI/CD): Integrating with CI/CD pipelines to automate the build, test, and deployment processes.
   • Example: Integrating with Jenkins to automate the deployment of a web application after successful testing.
5. Security and Compliance: Automating security updates and compliance checks.
   • Example: Ensuring that all servers have the latest security patches applied and compliance standards are met.

Ansible Cheatsheet for Beginners

Basic Concepts:

1. Inventory: A list of hosts managed by Ansible, defined in an inventory file.
2. Modules: Units of work in Ansible, such as tasks (e.g., installing software, copying files).
3. Playbooks: YAML files that define a series of tasks to be executed on managed hosts.
4. Roles: A way to group related tasks, variables, and files to organize playbooks.

Installation

Install Ansible on Ubuntu

sudo apt update
sudo apt install ansible -y

Install Ansible on CentOS/RHEL

sudo yum install epel-release -y
sudo yum install ansible -y

Basic Inventory File (hosts):

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

[databases]
db1.example.com
db2.example.com

Ansible Configuration File (ansible.cfg):

[defaults]
inventory = hosts
remote_user = your_username
host_key_checking = False

4. Ad-Hoc Commands

• Ping all hosts:

ansible all -m ping

Install a package:

ansible all -m apt -a "name=nginx state=present" --become

Copy a file:

ansible all -m copy -a "src=/path/to/local/file dest=/path/to/remote/file" --become

• Restart a service:

ansible all -m service -a "name=nginx state=restarted" --become

5. Playbook Structure

Basic Playbook Example (playbook.yml):

- name: Install and start Nginx
  hosts: webservers
  become: yes
  tasks:
    - name: Ensure Nginx is installed
      apt:
        name: nginx
        state: present
      when: ansible_os_family == "Debian"

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

Run the Playbook:

ansible-playbook playbook.yml

6. Common Modules

• Package Management:Copy code
• state: present - name: Install a package using yum yum: name: package_name state: present

- name: Install a package using apt
  apt:
    name: package_name
    state: present

- name: Install a package using yum
  yum:
    name: package_name
    state: present

• File Management:

- name: Copy a file
  copy:
    src: /path/to/local/file
    dest: /path/to/remote/file

- name: Manage file properties
  file:
    path: /path/to/remote/file
    state: touch
    mode: '0644'

• Service Management:

- name: Ensure a service is running
  service:
    name: service_name
    state: started

• User Management:yaml

- name: Create a user
  user:
    name: username
    state: present

• Template Management:

- name: Deploy a configuration file from a template
  template:
    src: /path/to/template.j2
    dest: /path/to/remote/config

7. Variables

Defining Variables in Playbooks:

- name: Using variables
  hosts: webservers
  vars:
    package_name: nginx
  tasks:
    - name: Ensure the package is installed
      apt:
        name: "{{ package_name }}"
        state: present
      when: ansible_os_family == "Debian"

Defining Variables in Inventory:

[webservers]
web1.example.com package_name=nginx
web2.example.com package_name=httpd

Using Variables in Tasks:

- name: Install package
  apt:
    name: "{{ package_name }}"
    state: present

8. Roles

Creating a Role:

ansible-galaxy init myrole

Directory Structure of a Role:

myrole/
├── tasks
│   └── main.yml
├── handlers
│   └── main.yml
├── templates
│   └── config.j2
├── files
│   └── myfile
├── vars
│   └── main.yml
├── defaults
│   └── main.yml
└── meta
    └── main.yml

Using a Role in a Playbook:

- name: Apply myrole
  hosts: webservers
  roles:
    - myrole

Conclusion

This detailed cheatsheet provides a comprehensive guide to getting started with Ansible, from installation and configuration to using modules, variables, and roles. As you become more familiar with Ansible, you can explore more advanced features and create complex automation tasks to streamline your IT operations.