Ansible for DevOps: Automating Server Configuration

Ansible is an agentless automation tool that uses SSH to configure servers, deploy applications, and orchestrate workflows. No daemons, no agents — just Python and SSH.

Why Ansible?

Agentless — nothing to install on managed nodes
Idempotent — running a playbook twice produces the same result
Declarative — describe the desired state, not the steps
Simple — YAML playbooks are readable by anyone

Installation

bash

# macOS
brew install ansible

# Ubuntu / Debian
sudo apt update
sudo apt install ansible

# Verify
ansible --version

Inventory

The inventory defines which servers Ansible manages. Create an inventory.ini:

ini

[webservers]
web1.example.com ansible_user=deploy
web2.example.com ansible_user=deploy

[databases]
db1.example.com ansible_user=deploy

[all:vars]
ansible_python_interpreter=/usr/bin/python3

Test connectivity:

bash

ansible all -i inventory.ini -m ping

Your First Playbook

Create setup-webserver.yml:

yaml

---
- name: Configure web servers
  hosts: webservers
  become: yes

  vars:
    app_port: 3000
    node_version: "20"

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

    - name: Install required packages
      apt:
        name:
          - nginx
          - curl
          - git
          - ufw
        state: present

    - name: Enable UFW firewall
      ufw:
        state: enabled
        policy: deny

    - name: Allow SSH
      ufw:
        rule: allow
        name: OpenSSH

    - name: Allow HTTP and HTTPS
      ufw:
        rule: allow
        port: "{{ item }}"
        proto: tcp
      loop:
        - "80"
        - "443"

    - name: Copy Nginx config
      template:
        src: templates/nginx.conf.j2
        dest: /etc/nginx/sites-available/default
      notify: Restart Nginx

  handlers:
    - name: Restart Nginx
      service:
        name: nginx
        state: restarted

Run it:

bash

ansible-playbook -i inventory.ini setup-webserver.yml

Roles

Roles organize playbooks into reusable components:

roles/
  nginx/
    tasks/main.yml
    templates/nginx.conf.j2
    handlers/main.yml
    defaults/main.yml
  nodejs/
    tasks/main.yml
    defaults/main.yml
  postgresql/
    tasks/main.yml
    templates/pg_hba.conf.j2
    handlers/main.yml

Use roles in a playbook:

yaml

---
- name: Full server setup
  hosts: webservers
  become: yes
  roles:
    - nginx
    - nodejs

Common Modules

Module	Purpose	Example
`apt` / `yum`	Package management	`apt: name=nginx state=present`
`copy`	Copy files	`copy: src=app.conf dest=/etc/app.conf`
`template`	Jinja2 templates	`template: src=nginx.j2 dest=/etc/nginx/nginx.conf`
`service`	Manage services	`service: name=nginx state=started enabled=yes`
`user`	Manage users	`user: name=deploy shell=/bin/bash`
`file`	File/directory ops	`file: path=/data state=directory mode=0755`
`git`	Clone repositories	`git: repo=https://github.com/... dest=/opt/app`
`docker_container`	Manage containers	`docker_container: name=app image=myapp:latest`

Ansible Vault

Encrypt sensitive variables:

bash

# Create encrypted file
ansible-vault create secrets.yml

# Edit encrypted file
ansible-vault edit secrets.yml

# Run playbook with vault
ansible-playbook -i inventory.ini site.yml --ask-vault-pass

Best Practices

Use --check mode (dry run) before applying changes
Group variables in group_vars/ and host-specific ones in host_vars/
Always use become: yes explicitly rather than running Ansible as root
Tag tasks so you can run subsets: ansible-playbook site.yml --tags "nginx"
Test playbooks with Molecule for role unit testing

Ansible makes server configuration repeatable and version-controlled. Combined with Git, it brings the same rigor to infrastructure that developers have for application code.

Ansible for DevOps: Automating Server Configuration

Why Ansible?

Installation

Inventory

Your First Playbook

Roles

Common Modules

Ansible Vault

Best Practices

Tagged with

Enjoyed this article?

Get new posts by email

Related Posts

Shell Scripting for DevOps: Essential Bash Automation

Securing Docker Containers: A Production Checklist

Nginx as a Reverse Proxy: Complete Configuration Guide

Discussion