# Ansible — Simple & Powerful IT Automation Platform

> Ansible is the industry-standard IT automation tool for configuration management, application deployment, and infrastructure provisioning. Agentless, YAML-based, and SSH-powered.

## Install

Save as a script file and run:

## Quick Use

```bash
# Install
pip install ansible

# Create inventory
cat > inventory.ini <<EOF
[webservers]
web1.example.com
web2.example.com
EOF

# Run ad-hoc command
ansible all -i inventory.ini -m ping

# Run playbook
ansible-playbook -i inventory.ini deploy.yml
```

## Intro

**Ansible** is a radically simple, open-source IT automation platform that makes applications and systems easier to deploy and maintain. Unlike tools that require agents on remote systems, Ansible uses SSH (or WinRM for Windows) to push configurations, making it agentless and easy to get started.

With 68.4K+ GitHub stars and GPL-3.0 license, Ansible is the most popular IT automation tool, used by millions of systems administrators and DevOps engineers to automate everything from code deployment to network configuration to cloud orchestration.

## What Ansible Does

- **Configuration Management**: Define desired system state in YAML, apply consistently across machines
- **Application Deployment**: Deploy applications across multiple servers with zero downtime
- **Orchestration**: Coordinate complex multi-tier deployments across environments
- **Provisioning**: Provision cloud resources (AWS, Azure, GCP) and virtual machines
- **Security & Compliance**: Enforce security policies and compliance standards
- **Network Automation**: Configure routers, switches, and firewalls from 30+ vendors
- **Continuous Delivery**: Integrate with CI/CD pipelines for automated deployment

## Architecture

```
┌──────────────┐
│ Control Node │  (Where Ansible is installed)
│  (Your       │
│   Laptop)    │
└──────┬───────┘
       │ SSH
       │
   ┌───┴────────────────────┐
   │                        │
┌──┴───┐  ┌────┐  ┌────┐  ┌┴───┐
│ Web1 │  │Web2│  │DB1 │  │DB2 │  ← No Ansible agent needed
│      │  │    │  │    │  │    │
└──────┘  └────┘  └────┘  └────┘
   Managed Nodes (any SSH-accessible machine)
```

Agentless design: Only Python needs to be installed on managed nodes (and most Linux systems have it by default).

## Core Concepts

### Inventory

```ini
# inventory.ini
[webservers]
web1.example.com
web2.example.com ansible_user=deploy

[dbservers]
db1.example.com
db2.example.com

[production:children]
webservers
dbservers

[webservers:vars]
nginx_port=80
app_env=production
```

Or YAML format:

```yaml
# inventory.yml
all:
  children:
    webservers:
      hosts:
        web1.example.com:
        web2.example.com:
          ansible_user: deploy
      vars:
        nginx_port: 80
    dbservers:
      hosts:
        db1.example.com:
        db2.example.com:
```

### Playbooks

```yaml
# deploy-web.yml
---
- name: Deploy web application
  hosts: webservers
  become: true

  vars:
    app_version: "2.1.0"
    app_dir: /var/www/myapp

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

    - name: Clone repository
      git:
        repo: https://github.com/myorg/myapp.git
        dest: "{{ app_dir }}"
        version: "v{{ app_version }}"

    - name: Install dependencies
      npm:
        path: "{{ app_dir }}"
        state: present

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

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

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

### Roles (Reusable Components)

```
roles/
└── webserver/
    ├── tasks/main.yml
    ├── handlers/main.yml
    ├── templates/nginx.conf.j2
    ├── files/
    ├── vars/main.yml
    ├── defaults/main.yml
    └── meta/main.yml
```

```yaml
# Using roles in a playbook
- hosts: webservers
  roles:
    - common
    - { role: webserver, nginx_port: 8080 }
    - { role: appserver, app_version: "2.0.0" }
```

## Common Modules

```yaml
# File operations
- file:
    path: /etc/myapp
    state: directory
    mode: '0755'

# Package management
- apt:          # Debian/Ubuntu
    name: nginx
    state: present

- yum:          # RHEL/CentOS
    name: httpd
    state: latest

# Service management
- service:
    name: postgresql
    state: started
    enabled: true

# Users and groups
- user:
    name: deploy
    groups: sudo
    shell: /bin/bash

# Templates
- template:
    src: config.j2
    dest: /etc/myapp/config.ini

# Command execution
- shell: |
    cd /app
    npm run build

# Cloud modules
- amazon.aws.ec2_instance:
    name: "web-{{ item }}"
    instance_type: t3.micro
    image_id: ami-12345
  loop: [1, 2, 3]
```

## Ad-Hoc Commands

```bash
# Ping all servers
ansible all -m ping

# Check disk space
ansible all -m shell -a "df -h"

# Restart service
ansible webservers -m service -a "name=nginx state=restarted" --become

# Copy file
ansible all -m copy -a "src=/local/file dest=/remote/file"

# Install package
ansible all -m apt -a "name=htop state=present" --become
```

## Ansible vs Alternatives

| Feature | Ansible | Puppet | Chef | Salt |
|---------|---------|--------|------|------|
| Open Source | Yes | Yes | Yes | Yes |
| Language | YAML | DSL (Ruby) | DSL (Ruby) | YAML |
| Agentless | Yes | No (agent) | No (agent) | Optional |
| Setup | Very easy | Moderate | Moderate | Moderate |
| Learning curve | Low | Medium | Medium | Medium |
| Push/Pull | Push | Pull | Pull | Both |
| Best for | General automation | Large infra | Developer-centric | Scale |

## 常见问题

**Q: Ansible 需要在被管理机器上安装 agent 吗？**
A: 不需要。只需要 Python（大多数 Linux 系统默认已安装）和 SSH 访问权限。Windows 系统需要配置 WinRM。

**Q: 适合多大规模的基础设施？**
A: 从个人服务器到数千台机器都适用。对于大规模部署，可以使用 Ansible Tower/AWX（Web UI + 任务调度）或 Ansible Pull 模式。

**Q: 和 Terraform 有什么区别？**
A: Terraform 主要用于基础设施供应（创建云资源），Ansible 主要用于配置管理（在机器上安装软件和配置）。两者经常配合使用：Terraform 创建服务器，Ansible 配置服务器。

## 来源与致谢

- GitHub: [ansible/ansible](https://github.com/ansible/ansible) — 68.4K+ ⭐ | GPL-3.0
- 官网: [ansible.com](https://ansible.com)

---
Source: https://tokrepo.com/en/workflows/92bab097-352f-11f1-9bc6-00163e2b0d79
Author: Script Depot