Ansible Complete Guide — Agentless Configuration Management

# Install Ansible (macOS)
pip3 install ansible
 
# Verify version
ansible --version
 
# Static inventory file
cat > inventory.ini << 'EOF'
[webservers]
web1.example.com ansible_user=ubuntu
web2.example.com ansible_user=ubuntu
 
[databases]
db1.example.com ansible_user=ubuntu ansible_port=2222
 
[production:children]
webservers
databases
 
[all:vars]
ansible_ssh_private_key_file=~/.ssh/prod_key
EOF
 
# Test connectivity
ansible all -i inventory.ini -m ping
 
# Run ad-hoc command
ansible webservers -i inventory.ini -m command -a "uptime"
ansible databases -i inventory.ini -m shell -a "df -h"

# Install AWS collection
ansible-galaxy collection install amazon.aws
 
# aws_ec2 dynamic inventory plugin
cat > aws_ec2.yaml << 'EOF'
plugin: amazon.aws.aws_ec2
regions:
  - us-east-1
filters:
  tag:Environment: production
keyed_groups:
  - key: tags.Role
    prefix: role
EOF
 
ansible-inventory -i aws_ec2.yaml --list
ansible all -i aws_ec2.yaml -m ping

---
# deploy-app.yml
- name: Deploy Node.js application
  hosts: webservers
  become: true
  vars:
    app_version: "{{ lookup('env', 'APP_VERSION') | default('latest') }}"
    app_port: 3000
    app_dir: /opt/my-app
 
  tasks:
    - name: Install Node.js dependencies
      apt:
        name:
          - nodejs
          - npm
          - nginx
        state: present
        update_cache: true
 
    - name: Create app directory
      file:
        path: "{{ app_dir }}"
        state: directory
        owner: ubuntu
        mode: '0755'
 
    - name: Copy application files
      copy:
        src: dist/
        dest: "{{ app_dir }}/"
        owner: ubuntu
        mode: '0644'
      notify: restart app
 
    - name: Install npm dependencies
      npm:
        path: "{{ app_dir }}"
        state: present
 
    - name: Configure nginx
      template:
        src: templates/nginx.conf.j2
        dest: /etc/nginx/sites-available/my-app
        mode: '0644'
      notify: reload nginx
 
    - name: Enable nginx site
      file:
        src: /etc/nginx/sites-available/my-app
        dest: /etc/nginx/sites-enabled/my-app
        state: link
 
  handlers:
    - name: restart app
      systemd:
        name: my-app
        state: restarted
 
    - name: reload nginx
      service:
        name: nginx
        state: reloaded

# Create role structure
ansible-galaxy init roles/webserver
 
# Directory structure
roles/webserver/
  tasks/main.yml
  handlers/main.yml
  templates/
  files/
  vars/main.yml
  defaults/main.yml
  meta/main.yml

# roles/webserver/tasks/main.yml
---
- name: Install web packages
  apt:
    name: "{{ webserver_packages }}"
    state: present
    update_cache: true
 
- name: Start and enable nginx
  systemd:
    name: nginx
    state: started
    enabled: true
 
- name: Deploy site configuration
  template:
    src: site.conf.j2
    dest: "/etc/nginx/sites-available/{{ site_name }}"
  notify: reload nginx
 
# roles/webserver/defaults/main.yml
---
webserver_packages:
  - nginx
  - curl
 
site_name: default
site_port: 80

# Using the role in a playbook
---
- hosts: webservers
  become: true
  roles:
    - role: webserver
      vars:
        site_name: my-app
        site_port: 8080

# group_vars/production/vars.yml
db_host: prod-db.example.com
db_port: 5432
app_env: production
 
# group_vars/production/vault.yml (encrypted)
# Create with: ansible-vault create group_vars/production/vault.yml
vault_db_password: "super-secret-password"
vault_api_key: "my-api-key"

# Encrypt a file
ansible-vault encrypt group_vars/production/vault.yml
 
# Edit encrypted file
ansible-vault edit group_vars/production/vault.yml
 
# Run playbook with vault password
ansible-playbook deploy.yml --ask-vault-pass
ansible-playbook deploy.yml --vault-password-file ~/.vault_pass