【自动化运维神器Ansible】playbook主机清单变量深度解析：主机变量与组变量的实战应用

• 语法格式：

hostname var1=value1 var2=value2

• 主机清单文件（inventory）：

[websrvs]
www1.example.com http_port=80 maxRequestsPerChild=808
www2.example.com http_port=8080 maxRequestsPerChild=909

• 变量调用示例（playbook.yml）：

---
- hosts: websrvs
  tasks:
    - name: Configure web server
      copy: 
        src: httpd.conf.j2 
        dest: /etc/httpd/conf/httpd.conf
      vars:
        # 根据主机变量动态配置
        listen_port: "{{ http_port }}"
        max_requests: "{{ maxRequestsPerChild }}"

• 模板文件（httpd.conf.j2）：

Listen {{ listen_port }}
MaxRequestsPerChild {{ max_requests }}

• 在主机清单文件中定义主机组
• 为每个主机指定专属变量
• 在Playbook中通过{{ variable_name }}调用变量
• 根据主机变量实现差异化配置

• 语法格式：

[groupname:vars]
var1=value1
var2=value2

• 主机清单文件（inventory）：

[websrvs]
www1.example.com
www2.example.com

[websrvs:vars]
http_port=8080
ntp_server=ntp.example.com
nfs_server=nfs.example.com

• Playbook应用示例：

---
- hosts: websrvs
  tasks:
    - name: Configure NTP client
      template: 
        src: ntp.conf.j2 
        dest: /etc/ntp.conf
      vars:
        ntp_server: "{{ ntp_server }}"
    
    - name: Mount NFS share
      mount: 
        path: /data 
        src: "{{ nfs_server }}:/data" 
        fstype: nfs 
        state: mounted

• 优先级流程：

• 主机清单文件：

[websrvs]
web1.example.com http_port=80
web2.example.com

[websrvs:vars]
http_port=8080

• Playbook文件：

---
- hosts: websrvs
  vars:
    http_port: 9090
  tasks:
    - name: Show port
      debug: msg="Port: {{ http_port }}"

ansible-project/
├── inventory/
│   ├── production
│   ├── staging
│   └── development
├── group_vars/
│   ├── all.yml
│   ├── webservers.yml
│   └── dbservers.yml
├── host_vars/
│   ├── web1.example.com.yml
│   └── db1.example.com.yml
└── playbooks/
    ├── deploy_web.yml
    └── deploy_db.yml

• 生产环境清单（inventory/production）：

[webservers]
web1.prod.example.com http_port=80 max_connections=1000
web2.prod.example.com http_port=80 max_connections=2000
web3.prod.example.com http_port=8080 max_connections=1500

[dbservers]
db1.prod.example.com db_port=3306 db_memory=8192
db2.prod.example.com db_port=3306 db_memory=16384

[webservers:vars]
app_name="production_app"
cache_enabled=true
ssl_enabled=true

[dbservers:vars]
app_name="production_db"
backup_enabled=true

• 公共变量（group_vars/all.yml）：

---
# 公共配置
ansible_user: "deploy"
ansible_ssh_private_key_file: "~/.ansible/keys/deploy_key"
backup_dir: "/backup"
log_level: "INFO"

• Web服务器变量（group_vars/webservers.yml）：

---
# Web服务器特定配置
nginx_version: "1.18.0"
php_version: "7.4"
max_workers: 4

• Web1服务器变量（host_vars/web1.example.com.yml）：

---
# Web1专属配置
http_port: 80
max_connections: 1000
ssl_cert: "/etc/ssl/certs/web1.crt"
ssl_key: "/etc/ssl/private/web1.key"

• Web部署Playbook（playbooks/deploy_web.yml）：

---
- name: Deploy Web Servers
  hosts: webservers
  vars_files:
    - ../group_vars/all.yml
    - ../group_vars/webservers.yml
  tasks:
    - name: Install web packages
      yum: 
        name: "{{ item }}" 
        state=present
      loop:
        - "nginx-{{ nginx_version }}"
        - "php-{{ php_version }}"
        - "php-fpm"
    
    - name: Configure nginx
      template: 
        src: nginx.conf.j2 
        dest: /etc/nginx/nginx.conf
      vars:
        listen_port: "{{ http_port }}"
        max_conn: "{{ max_connections }}"
        ssl_cert_path: "{{ ssl_cert | default('/etc/ssl/certs/default.crt') }}"
        ssl_key_path: "{{ ssl_key | default('/etc/ssl/private/default.key') }}"
    
    - name: Start services
      service: 
        name: "{{ item }}" 
        state=started 
        enabled=yes
      loop:
        - nginx
        - php-fpm