Ansible 基础(2)：从 Ad-Hoc 到 Playbook 的标准化实战与变量体系详解#

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---
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# 顶部的三个短横线表示 YAML 文件的开始（可选，但推荐保留）
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- name: My First Playbook         # Play 的名称，用于描述整个流程的目的
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  hosts: webservers               # 指定目标主机组（对应 inventory 中的组名）
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  become: yes                     # 开启权限提升（相当于 sudo）
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  become_user: root               # 提升为 root 用户执行
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  gather_facts: no                # 是否收集主机系统信息（不需要时关闭可提升执行速度）
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  tasks:                          # 任务列表开始
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    - name: Ensure Apache is installed  # Task 1 的名称
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      yum:                              # 调用的模块名称
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        name: httpd                     # 模块参数：软件包名
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        state: present                  # 模块参数：期望状态为已安装
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    - name: Ensure Apache is running    # Task 2 的名称
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      service:                          # 调用的模块名称
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        name: httpd                     # 模块参数：服务名
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        state: started                  # 模块参数：期望状态为启动
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        enabled: yes                    # 模块参数：开机自启

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---
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- name: Deploy Nginx Directory and Configuration
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  hosts: webservers
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  become: yes
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  tasks:
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    - name: Create nginx log directory
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      file:
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        path: /data/logs/nginx/
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        state: directory      # 状态为 directory 表示创建目录
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        owner: root
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        group: root
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        mode: '0755'          # 权限必须用引号引起来，否则 YAML 会解析为八进制数字
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        recurse: yes          # 相当于 mkdir -p 递归创建
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    - name: Distribute nginx.conf to web nodes
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      copy:
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        src: ./files/nginx.conf  # Ansible 控制节点上的源文件路径（相对剧本位置）
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        dest: /etc/nginx/nginx.conf # 目标节点路径
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        owner: root
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        group: root
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        mode: '0644'
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        backup: yes           # 如果目标文件已存在且内容不同，覆盖前自动备份

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---
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- name: Install and Start Nginx Service
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  hosts: webservers
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  become: yes
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  tasks:
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    - name: Install EPEL release repository
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      yum:
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        name: epel-release
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        state: present
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    - name: Install Nginx package
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      yum:
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        name: nginx
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        state: latest         # latest 表示确保安装最新版本
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    - name: Deploy custom index.html
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      copy:
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        src: ./files/index.html
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        dest: /usr/share/nginx/html/index.html
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        mode: '0644'
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    - name: Start Nginx and enable on boot
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      systemd:
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        name: nginx
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        state: started        # 确保服务处于运行状态
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        enabled: yes          # systemctl enable nginx

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---
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# ==========================================
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# Play 1: 针对 NFS 服务端进行配置
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# ==========================================
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- name: Setup NFS Server
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  hosts: nfs-server
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  become: yes
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  tasks:
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    - name: Install nfs-utils on server
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      yum:
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        name: nfs-utils
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        state: present
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    - name: Create shared directory
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      file:
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        path: /data/shared
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        state: directory
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        owner: nfsnobody
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        group: nfsnobody
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        mode: '0777'
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    - name: Configure /etc/exports
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      copy:
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        content: "/data/shared 192.168.10.0/24(rw,sync,all_squash)\n"
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        dest: /etc/exports
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    - name: Start rpcbind and nfs services
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      systemd:
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        name: "{{ item }}"
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        state: started
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        enabled: yes
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      loop:                   # 使用循环简化多个服务的启动
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        - rpcbind
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        - nfs
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# ==========================================
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# Play 2: 针对 Web 客户端进行挂载配置
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# ==========================================
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- name: Setup NFS Clients
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  hosts: webservers
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  become: yes
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  tasks:
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    - name: Install nfs-utils on clients
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      yum:
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        name: nfs-utils
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        state: present
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    - name: Create mount point
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      file:
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        path: /var/www/html/shared
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        state: directory
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    - name: Mount NFS share directory
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      mount:                  # mount 模块不仅执行 mount，还会自动写入 /etc/fstab
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        path: /var/www/html/shared
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        src: 192.168.10.10:/data/shared
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        fstype: nfs
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        opts: defaults
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        state: mounted        # mounted 表示挂载并写入 fstab

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# 错误写法（YAML 语法解析报错）：
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path: {{ base_dir }}/logs
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# 正确写法：
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path: "{{ base_dir }}/logs"

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---
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- name: Install App with Play Vars
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  hosts: webservers
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  vars:
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    app_name: redis
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    app_port: 6379
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    install_path: /opt/redis
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  tasks:
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    - name: Print variable
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      debug:
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        msg: "Installing {{ app_name }} on port {{ app_port }} at {{ install_path }}"

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nginx_port: 8080
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nginx_user: www

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---
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- name: Use external variables file
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  hosts: webservers
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  vars_files:
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    - variables/main.yml
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  tasks:
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    - name: Show port
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      debug:
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        msg: "Nginx will listen on {{ nginx_port }}"

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---
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- name: Cross-platform Package Installation
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  hosts: all
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  tasks:
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    - name: Install Apache on RedHat/CentOS
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      yum:
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        name: httpd
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        state: present
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      when: ansible_facts['os_family'] == "RedHat"   # 使用 facts 变量进行条件判断
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    - name: Install Apache on Debian/Ubuntu
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      apt:
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        name: apache2
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        state: present
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      when: ansible_facts['os_family'] == "Debian"

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---
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- name: Check Port and Act
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  hosts: webservers
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  tasks:
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    - name: Check if port 8080 is listening
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      shell: "netstat -tlnp | grep 8080"
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      register: port_check_result    # 将 shell 命令的执行结果注册到此变量
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      ignore_errors: yes             # 忽略报错，防止 grep 查不到时中断剧本
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    - name: Print the standard output
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      debug:
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        msg: "Port info: {{ port_check_result.stdout }}"
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    - name: Restart application if port is not listening
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      systemd:
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        name: myapp
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        state: restarted
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      when: port_check_result.rc != 0  # 如果返回码不为0（未监听到），则执行重启