Ansible自动化运维入门

什么是Ansible

Ansible是一个无代理的自动化工具，通过SSH协议管理远程主机，实现配置管理、应用部署和任务自动化。

核心特点

• 无代理：不需要在被管理节点安装客户端
• 简单：使用YAML编写Playbook
• 强大：支持复杂的工作流
• 安全：通过SSH传输，支持Ansible Vault加密

安装Ansible

# 使用pip安装
pip install ansible

# Ubuntu/Debian
sudo apt-get install ansible

# 验证安装
ansible --version

Inventory

静态Inventory

# /etc/ansible/hosts 或 inventory.ini
[webservers]
web1 ansible_host=192.168.1.10
web2 ansible_host=192.168.1.11

[dbservers]
db1 ansible_host=192.168.1.20

[production:children]
webservers
dbservers

YAML Inventory

# inventory.yml
all:
  children:
    webservers:
      hosts:
        web1:
          ansible_host: 192.168.1.10
        web2:
          ansible_host: 192.168.1.11
    dbservers:
      hosts:
        db1:
          ansible_host: 192.168.1.20

Ad-hoc命令

# 测试连接
ansible all -m ping

# 执行命令
ansible webservers -m shell -a "uptime"

# 复制文件
ansible webservers -m copy -a "src=/local/file dest=/remote/file"

# 安装包
ansible webservers -m apt -a "name=nginx state=present" --become

# 服务管理
ansible webservers -m service -a "name=nginx state=started" --become

Playbook

基本结构

# deploy.yml
---
- name: Deploy web application
  hosts: webservers
  become: yes
  
  vars:
    app_name: myapp
    app_port: 8080
  
  tasks:
    - name: Install dependencies
      apt:
        name:
          - nginx
          - python3
          - python3-pip
        state: present
        update_cache: yes
    
    - name: Copy nginx config
      template:
        src: templates/nginx.conf.j2
        dest: /etc/nginx/sites-available/default
      notify: Restart nginx
    
    - name: Copy application
      copy:
        src: app/
        dest: /opt/myapp/
        owner: www-data
        group: www-data
        mode: '0644'
    
    - name: Start nginx
      service:
        name: nginx
        state: started
        enabled: yes
  
  handlers:
    - name: Restart nginx
      service:
        name: nginx
        state: restarted

执行Playbook

# 执行playbook
ansible-playbook deploy.yml

# 检查模式（dry run）
ansible-playbook deploy.yml --check

# 指定inventory
ansible-playbook -i inventory.yml deploy.yml

# 限制主机
ansible-playbook deploy.yml --limit webservers

Role

目录结构

roles/
  nginx/
    tasks/
      main.yml
    handlers/
      main.yml
    templates/
      nginx.conf.j2
    files/
    vars/
      main.yml
    defaults/
      main.yml

使用Role

# site.yml
---
- hosts: webservers
  become: yes
  roles:
    - nginx
    - myapp

变量优先级

角色默认变量 < inventory变量 < playbook vars < extra vars

实践：部署Nginx

# deploy-nginx.yml
---
- name: Deploy Nginx
  hosts: webservers
  become: yes
  
  vars:
    nginx_port: 80
    server_name: example.com
  
  tasks:
    - name: Install Nginx
      apt:
        name: nginx
        state: present
        update_cache: yes
    
    - name: Create nginx config
      template:
        src: nginx.conf.j2
        dest: /etc/nginx/sites-available/default
      notify: Restart nginx
    
    - name: Enable site
      file:
        src: /etc/nginx/sites-available/default
        dest: /etc/nginx/sites-enabled/default
        state: link
    
    - name: Start Nginx
      service:
        name: nginx
        state: started
        enabled: yes
  
  handlers:
    - name: Restart nginx
      service:
        name: nginx
        state: restarted

ansible-playbook deploy-nginx.yml

总结

Ansible是DevOps工程师的重要工具。通过Playbook和Role，可以实现基础设施即代码，提高运维效率和一致性。