ansible

name	ansible
description	Ansible automation for server configuration, deployment, and infrastructure management. Use when user mentions "ansible", "ansible-playbook", "ansible-vault", "inventory", "playbook", "ansible role", "ansible galaxy", "configuration management", "server provisioning", "infrastructure automation", "ansible task", "ansible template", or automating server setup and deployment.

Ansible

Agentless automation over SSH. No agents to install on managed nodes -- just Python on targets and SSH access. All modules are idempotent by default: running a playbook twice produces the same result.

Ad-Hoc Commands

# Ping all hosts
ansible all -m ping

# Run command on web servers
ansible webservers -m command -a "uptime"
ansible webservers -m shell -a "df -h | grep /dev/sda"

# Copy file
ansible webservers -m copy -a "src=./app.conf dest=/etc/app.conf owner=root mode=0644"

# Install package
ansible webservers -m apt -a "name=nginx state=present" --become

# Manage service
ansible webservers -m systemd -a "name=nginx state=restarted enabled=yes" --become

# Create user
ansible all -m user -a "name=deploy shell=/bin/bash groups=sudo" --become

# Gather facts
ansible webservers -m setup -a "filter=ansible_distribution*"

Inventory

Static Inventory (hosts.ini)

[webservers]
web1.example.com ansible_host=10.0.1.10
web2.example.com ansible_host=10.0.1.11

[dbservers]
db1.example.com ansible_host=10.0.2.10 ansible_port=2222

[production:children]
webservers
dbservers

[webservers:vars]
ansible_user=deploy
ansible_python_interpreter=/usr/bin/python3

[all:vars]
ansible_ssh_private_key_file=~/.ssh/deploy_key

YAML Inventory (inventory.yml)

all:
  children:
    webservers:
      hosts:
        web1.example.com:
          ansible_host: 10.0.1.10
          http_port: 8080
        web2.example.com:
          ansible_host: 10.0.1.11
    dbservers:
      hosts:
        db1.example.com:
          ansible_host: 10.0.2.10
      vars:
        db_port: 5432

Host and Group Variables

inventory/
  hosts.yml
  group_vars/
    all.yml            # Applies to every host
    webservers.yml     # Applies to webservers group
    production.yml
  host_vars/
    web1.example.com.yml

Dynamic Inventory

# AWS EC2
ansible-inventory -i aws_ec2.yml --list

# Plugin config (aws_ec2.yml)

plugin: amazon.aws.aws_ec2
regions:
  - us-east-1
filters:
  tag:Environment: production
keyed_groups:
  - key: tags.Role
    prefix: role
compose:
  ansible_host: private_ip_address

Playbook Structure

---
- name: Configure web servers
  hosts: webservers
  become: yes
  vars:
    app_port: 8080
    app_user: www-data

  pre_tasks:
    - name: Update apt cache
      apt:
        update_cache: yes
        cache_valid_time: 3600

  tasks:
    - name: Install nginx
      apt:
        name: nginx
        state: present

    - name: Deploy nginx config
      template:
        src: nginx.conf.j2
        dest: /etc/nginx/sites-available/default
        owner: root
        mode: "0644"
      notify: Restart nginx

    - name: Ensure nginx  
      
         
         
         

  
       
      
         
         

  
         
      
         
         

# Run playbook
ansible-playbook site.yml
ansible-playbook site.yml -i inventory/hosts.yml
ansible-playbook site.yml --limit webservers
ansible-playbook site.yml --check          # Dry run
ansible-playbook site.yml --diff           # Show file changes
ansible-playbook site.yml -e "app_port=9090"
ansible-playbook site.yml --start-at-task="Deploy nginx config"

Common Modules

# Package management
- apt:
    name: [nginx, curl, git]
    state: present
- yum:
    name: httpd
    state: latest

# Files and directories
- file:
    path: /opt/app
    state: directory
    owner: deploy
    group: deploy
    mode: "0755"
- file:
    path: /tmp/old_file
    state: absent

# Copy files
- copy:
    src: files/app.conf
    dest: /etc/app/app.conf
    owner: root
    mode: "0644"
    backup: yes
- copy:
    content: "{{ lookup('template', 'config.j2') }}"
    dest: /etc/app/config.yml

# Templates
- template:
     
     
     


 
     
     
     
     


 
     
     
     [, ]
     
     
 
     
     


 
     
     
     
     


 
     
     
     
     
    
       
    
       


 
     
     
     


  
  
     
     
      
   
   


 
     
     
     
     

Variables and Facts

# Variable precedence (lowest to highest):
# role defaults -> inventory vars -> playbook vars -> role vars
# -> include_vars -> set_fact -> extra vars (-e)

# Register output
- command: whoami
  register: current_user
- debug:
    msg: "Running as {{ current_user.stdout }}"

# Set facts dynamically
- set_fact:
    app_version: "{{ lookup('file', 'VERSION') }}"
    deploy_timestamp: "{{ ansible_date_time.iso8601 }}"

# Access facts
- debug:
    msg: "OS: {{ ansible_distribution }} {{ ansible_distribution_version }}"
- debug:
    msg: "IP: {{ ansible_default_ipv4.address }}"
- debug:
    msg: "Memory: {{ ansible_memtotal_mb }} MB"

# Include vars from file
- include_vars:
    file: "{{ ansible_distribution | lower }}.yml"

Jinja2 Templates

{# templates/nginx.conf.j2 #}
server {
    listen {{ http_port | default(80) }};
    server_name {{ server_name }};

    {% if ssl_enabled | default(false) %}
    listen 443 ssl;
    ssl_certificate     /etc/ssl/certs/{{ domain }}.crt;
    ssl_certificate_key /etc/ssl/private/{{ domain }}.key;
    {% endif %}

    {% for location in app_locations %}
    location {{ location.path }} {
        proxy_pass http://{{ location.upstream }};
    }
    {% endfor %}

    access_log /var/log/nginx/{{ server_name }}_access.log;
}

Common Jinja2 filters:

# Defaults
"{{ variable | default('fallback') }}"

# String
"{{ name | upper }}"
"{{ name | lower }}"
"{{ path | basename }}"
"{{ path | dirname }}"

# Lists
"{{ packages | join(', ') }}"
"{{ users | map(attribute='name') | list }}"
"{{ items | unique | sort }}"

# Data
"{{ dict_var | to_json }}"
"{{ dict_var | to_yaml }}"
"{{ 'password' | password_hash('sha512') }}"

# Ternary
"{{ 'yes' if enabled else 'no' }}"

Conditionals and Loops

# When conditional
- apt:
    name: nginx
  when: ansible_distribution == "Ubuntu"

- yum:
    name: httpd
  when: ansible_os_family == "RedHat"

- service:
    name: app
    state: restarted
  when: deploy_result is changed

- debug:
    msg: "Low disk"
  when: ansible_mounts | selectattr('mount', 'equalto', '/') | map(attribute='size_available') | first < 1073741824

# Loops
- user:
    name: "{{ item }}"
    state: present
  loop:
    - alice
    - bob
     

 
     
     
  
     {  ,   }
     {  ,   }


 
     
   
  
     
     


 
     
     
   
     
   
   

Error Handling

# Ignore errors
- command: /opt/app/check.sh
  ignore_errors: yes
  register: check_result

# Custom failure condition
- command: /opt/app/status.sh
  register: status
  failed_when: "'ERROR' in status.stdout"
  changed_when: "'UPDATED' in status.stdout"

# Block / rescue / always (try/catch/finally)
- block:
    - name: Deploy application
      git:
        repo: https://github.com/org/app.git
        dest: /opt/app
        version: "{{ app_version }}"
    - name: Run migrations
      command: ./migrate.sh
      args:
        chdir: /opt/app
  rescue:
    - name: Rollback on failure
      command: ./rollback.sh
      args:
        chdir: /opt/app
    -    
      
         
         
         
  
       
      
         
         

Tags

- name: Install packages
  apt:
    name: nginx
  tags: [packages, nginx]

- name: Configure nginx
  template:
    src: nginx.conf.j2
    dest: /etc/nginx/nginx.conf
  tags: [config, nginx]

- name: Deploy application
  git:
    repo: https://github.com/org/app.git
    dest: /opt/app
  tags: [deploy]

ansible-playbook site.yml --tags "deploy"
ansible-playbook site.yml --skip-tags "packages"
ansible-playbook site.yml --tags "config,nginx"
ansible-playbook site.yml --list-tags

Roles

Directory Structure

roles/
  webserver/
    defaults/main.yml      # Default variables (lowest precedence)
    vars/main.yml          # Role variables (high precedence)
    tasks/main.yml         # Task list
    handlers/main.yml      # Handlers
    templates/             # Jinja2 templates
    files/                 # Static files
    meta/main.yml          # Role metadata and dependencies

Example Role

# roles/webserver/defaults/main.yml
http_port: 80
server_name: localhost
document_root: /var/www/html

# roles/webserver/tasks/main.yml
---
- name: Install nginx
  apt:
    name: nginx
    state: present

- name: Deploy config
  template:
    src: nginx.conf.j2
    dest: /etc/nginx/sites-available/default
  notify: Reload nginx

- name: Enable site
  file:
    src: /etc/nginx/sites-available/default
    dest: /etc/nginx/sites-enabled/default
    state: link

# roles/webserver/handlers/main.yml
---
- name: Reload nginx
  systemd:
    name: nginx
    state: reloaded

# roles/webserver/meta/main.yml
---
dependencies:
    
    
    
       [, ]

# Use role in playbook
- hosts: webservers
  become: yes
  roles:
    - common
    - { role: webserver, http_port: 8080 }
    - role: ssl
      when: ssl_enabled | default(false)

Ansible Galaxy

# Install roles
ansible-galaxy install geerlingguy.docker
ansible-galaxy install -r requirements.yml

# Install collections
ansible-galaxy collection install community.docker
ansible-galaxy collection install -r requirements.yml

# Initialize new role
ansible-galaxy role init my_role

# List installed
ansible-galaxy list
ansible-galaxy collection list

# requirements.yml
roles:
  - name: geerlingguy.docker
    version: "6.1.0"
  - name: geerlingguy.certbot
  - src: https://github.com/org/custom-role.git
    name: custom_role
    version: main

collections:
  - name: community.docker
    version: ">=3.0.0"
  - name: amazon.aws
    version: "7.0.0"

Ansible Vault

# Encrypt a file
ansible-vault encrypt vars/secrets.yml

# Decrypt
ansible-vault decrypt vars/secrets.yml

# Edit encrypted file in-place
ansible-vault edit vars/secrets.yml

# View without decrypting
ansible-vault view vars/secrets.yml

# Change encryption password
ansible-vault rekey vars/secrets.yml

# Encrypt a single string
ansible-vault encrypt_string 'SuperSecret123' --name 'db_password'

# Run playbook with vault
ansible-playbook site.yml --ask-vault-pass
ansible-playbook site.yml --vault-password-file ~/.vault_pass

# vars/secrets.yml (encrypted content)
db_password: !vault |
  $ANSIBLE_VAULT;1.1;AES256
  6234613839383...

# ansible.cfg - avoid typing password every time
[defaults]
vault_password_file = ~/.vault_pass

Docker and Container Management

# Requires: ansible-galaxy collection install community.docker

- name: Deploy containerized app
  hosts: docker_hosts
  become: yes
  collections:
    - community.docker

  tasks:
    - name: Install Docker
      include_role:
        name: geerlingguy.docker

    - name: Pull image
      docker_image:
        name: myapp
        tag: "{{ app_version }}"
        source: pull

    - name: Run app container
      docker_container:
        name: myapp
        image: "myapp:{{ app_version }}"
        state: started
        restart_policy: unless-stopped
        ports:
          - "8080:8080"
        env:
          DATABASE_URL: ""
           
        
           
        
            

        
      
         
         
         

Testing with Molecule

pip install molecule molecule-docker

# Initialize
cd roles/webserver
molecule init scenario --driver-name docker

# Test lifecycle
molecule create       # Create test instance
molecule converge     # Run role against instance
molecule verify       # Run tests
molecule destroy      # Clean up
molecule test         # Full cycle (create -> converge -> verify -> destroy)

# molecule/default/molecule.yml
dependency:
  name: galaxy
driver:
  name: docker
platforms:
  - name: ubuntu
    image: ubuntu:22.04
    pre_build_image: false
    command: /sbin/init
    privileged: true
  - name: rocky
    image: rockylinux:9
    command: /sbin/init
    privileged: true
provisioner:
  name: ansible
verifier:
  name: ansible

# molecule/default/verify.yml
---
- name: Verify
  hosts: all
  tasks:
    - name: Check nginx is running
      command: systemctl is-active nginx
      changed_when: false
    - name: Check  
      
         
         

Performance Tuning

# ansible.cfg
[defaults]
forks = 20                          # Parallel host connections (default 5)
gathering = smart                   # Cache facts, don't re-gather
fact_caching = jsonfile
fact_caching_connection = /tmp/ansible_facts
fact_caching_timeout = 86400
host_key_checking = False
stdout_callback = yaml              # Readable output

[ssh_connection]
pipelining = True                   # Reduce SSH operations (requires requiretty off)
ssh_args = -o ControlMaster=auto -o ControlPersist=60s

# Async tasks for long operations
- name: Long running update
  apt:
    upgrade: dist
  async: 3600       # Max runtime in seconds
  poll: 10          # Check every 10 seconds (0 = fire and forget)

# Limit fact gathering
- hosts: webservers
  gather_facts: no
  tasks:
    - setup:
        gather_subset:
          - network
          - hardware

# Free strategy (don't wait for all hosts per task)
- hosts: webservers
  strategy: free
  tasks:
    - name: Independent task
      apt:
        name: curl

For Mitogen (3-7x speedup), install mitogen and set strategy_plugins and strategy = mitogen_linear in ansible.cfg.

Common Patterns

Deploy Application

- hosts: webservers
  become: yes
  serial: "30%"          # Rolling deploy
  max_fail_percentage: 10

  pre_tasks:
    - name: Remove from load balancer
      uri:
        url: "http://lb.internal/api/remove/{{ inventory_hostname }}"
        method: POST

  roles:
    - app_deploy

  post_tasks:
    - name: Add back to load balancer
      uri:
        url: "http://lb.internal/api/add/{{ inventory_hostname }}"
        method: POST

    - name: Health check
      uri:
        url: "http://localhost:{{ app_port }}/health"
        status_code: 200
      retries: 10
      delay: 3

Setup Users and SSH

- name: Configure users
  hosts: all
  become: yes
  tasks:
    - name: Create users
      user:
        name: "{{ item.name }}"
        groups: "{{ item.groups | default([]) }}"
        shell: /bin/bash
      loop: "{{ admin_users }}"

    - name: Add SSH keys
      authorized_key:
        user: "{{ item.name }}"
        key: "{{ item.ssh_key }}"
      loop: "{{ admin_users }}"

    - name: Sudoers entry
      lineinfile:
        path: /etc/sudoers.d/{{ item.name }}
        line: "{{ item.name }} ALL=(ALL) NOPASSWD:ALL"
        create: yes
        mode: