Introduction to Configuration Management with Ansible

What is Ansible ? 🧐

Ansible is an open-source automation tool used for configuration management, application deployment, and task automation. It is designed to be simple, agentless, and easy to use.

Ansible uses a declarative language for system configurations and automation tasks, allowing you to define the desired system state instead of specifying individual steps.

Use Cases of Ansible:

• Exploring practical applications, such as configuration management, application deployment, and task automation.

• Emphasizing the role of Ansible in enabling efficient and scalable DevOps practices.

Setting Up Master and Agent :

• Install Ansible on the master server.

  

  

  

• Setting Up the Inventory File.

  There are two ways to set up the Inventory file:

  One way is to add the agents' IP addresses in the hosts file

    sudo vim /etc/ansible/hosts
  

  

  And the other way is to create an inventory file in the current location.

  

  

• Create an SSH key pair on the Ansible master by using the ssh-keygen command. This will generate a public key (id_rsa.pub) and a private key (id_rsa).

    ssh-keygen
  

  

• Copy Public Key to Agent Nodes:

  • Open the public key file (id_rsa.pub) and copy its contents.

      cat ~/.ssh/id_rsa.pub
    

  • Create an SSH key pair on the Ansible agents using the ssh-keygen command. Then, log in to each agents and add the copied public key to the authorized_keys file.

      ssh-keygen
    

    

    

Ad-hoc Commands:

Ad-hoc commands in Ansible are concise, one-line tasks used for quick checks or tasks on remote hosts without the need for a full playbook. They are run from the command line and offer a convenient way to engage with remote systems.

Examples:

• Ping Test

    ansible -i inventory all -m ping
  

  

• Check Free Disk Space

    ansible -i inventory all -m "shell" -a "df -h"
  

  

Ansible Playbook:

An Ansible playbook is a YAML file that outlines tasks to run on remote hosts. Playbooks automate tasks, configurations, and deployments in a reusable way. Each playbook comprises one or more plays, and each play includes a list of tasks.

Examples:

• Nginx Playbook

    ---
    - name: Nginx Installation and Configuration
      hosts: all
      become: true
  
      tasks:
        - name: Install Nginx
          apt:
            name: nginx
            state: present
  
        - name: Start Nginx service
          service:
            name: nginx
            state: started
            enabled: yes
  

  

  Run the playbook:

    ansible-playbook -i inventory nginx_playbook.yml
  

  

• Docker Playbook

    ---
    - name: Docker Installation
      hosts: all
      become: true
  
      tasks:
        - name: Install required packages
          apt:
            name:
              - apt-transport-https
              - ca-certificates
              - curl
              - gnupg-agent
              - software-properties-common
            state: present
  
        - name: Add Docker GPG key
          apt_key:
            url: https://download.docker.com/linux/ubuntu/gpg
            state: present
  
        - name: Add Docker APT repository
          apt_repository:
            repo: "deb [arch=amd64] https://download.docker.com/linux/ubuntu {{ ansible_distribution_release }} stable"
            state: present
  
        - name: Update apt package cache again
          apt:
            update_cache: yes
  
        - name: Install Docker
          apt:
            name:
              - docker-ce
              - docker-ce-cli
              - containerd.io
            state: present
  
        - name: Start Docker service
          service:
            name: docker
            state: started
            enabled: yes
  

  

  Happy Learning ^_^