Ansible

Ansible

Ansible is an agentless automation tool for configuration management, application deployment, and task automation. It uses SSH to connect to managed nodes.

Ansible vs Other Tools

  Agent-based (Puppet, Chef):      Agentless (Ansible):
  ┌────────────────────┐          ┌────────────────────┐
  │ Install agent on   │          │ No agent needed     │
  │ every server       │          │ Uses SSH            │
  │                    │          │                     │
  │  ┌──┐  ┌──┐  ┌──┐│          │  ┌──┐  ┌──┐  ┌──┐│
  │  │A │  │A │  │A ││          │  │  │  │  │  │  ││
  │  └──┘  └──┘  └──┘│          │  └──┘  └──┘  └──┘│
  │  Servers with agents│        │  Servers (plain)   │
  └────────────────────┘          └────────────────────┘

Ansible Playbook

  # deploy-app.yml
  ---
  - name: Deploy web application
    hosts: webservers
    become: yes
    vars:
      app_version: "2.1.0"
      app_port: 8080

    tasks:
      - name: Install dependencies
        apt:
          name:
            - nginx
            - python3
            - python3-pip
          state: present
          update_cache: yes

      - name: Copy application code
        copy:
          src: ./dist/
          dest: /opt/myapp/
          owner: www-data
          group: www-data

      - name: Configure nginx
        template:
          src: templates/nginx.conf.j2
          dest: /etc/nginx/sites-available/myapp
        notify: Reload nginx

      - name: Ensure services are running
        service:
          name: "{{ item }}"
          state: started
          enabled: yes
        loop:
          - nginx
          - myapp

    handlers:
      - name: Reload nginx
        service:
          name: nginx
          state: reloaded

Ansible Inventory

  # inventory/hosts.yml
  all:
    children:
      webservers:
        hosts:
          web1.example.com:
          web2.example.com:
      databases:
        hosts:
          db1.example.com:
          db2.example.com:
    vars:
      ansible_user: deploy
      ansible_ssh_private_key_file: ~/.ssh/deploy_key

Key Ansible Concepts

• Playbooks — YAML files defining automation tasks
• Roles — Reusable collections of tasks, handlers, and templates
• Inventory — List of servers to manage
• Modules — Built-in units of work (apt, copy, service, etc.)
• Galaxy — Community marketplace for Ansible roles