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342 lines
12 KiB
Markdown
[#]: collector: "lujun9972"
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[#]: translator: "MjSeven"
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[#]: reviewer: "wxy"
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[#]: publisher: "wxy"
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[#]: url: "https://linux.cn/article-13167-1.html"
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[#]: subject: "Ansible Playbooks Quick Start Guide with Examples"
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[#]: via: "https://www.2daygeek.com/ansible-playbooks-quick-start-guide-with-examples/"
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[#]: author: "Magesh Maruthamuthu https://www.2daygeek.com/author/magesh/"
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Ansible 剧本快速入门指南
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======
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我们已经写了两篇关于 Ansible 的文章，这是第三篇。
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如果你是 Ansible 新手，我建议你阅读下面这两篇文章，它会教你一些 Ansible 的基础以及它是什么。
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* 第一篇: [Ansible 自动化工具安装、配置和快速入门指南][1]
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* 第二篇: [Ansible 点对点命令快速入门指南示例][2]
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如果你已经阅读过了，那么在阅读本文时你才不会感到突兀。
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### 什么是 Ansible 剧本?
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<ruby>剧本<rt>playbook</rt></ruby>比点对点命令模式更强大，而且完全不同。
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它使用了 `/usr/bin/ansible-playbook` 二进制文件，并且提供丰富的特性使得复杂的任务变得更容易。
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如果你想经常运行一个任务，剧本是非常有用的。此外，如果你想在服务器组上执行多个任务，它也是非常有用的。
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剧本是由 YAML 语言编写。YAML 代表一种标记语言，它比其它常见的数据格式（如 XML 或 JSON）更容易读写。
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下面这张 Ansible 剧本流程图将告诉你它的详细结构。
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![][3]
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### 理解 Ansible 剧本的术语
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* <ruby>控制节点<rt>Control node</rt></ruby>：Ansible 安装的机器，它负责管理客户端节点。
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* <ruby>受控节点<rt>Managed node</rt></ruby>：控制节点管理的主机列表。
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* <ruby>剧本<rt>playbook</rt></ruby>：一个剧本文件包含一组自动化任务。
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* <ruby>主机清单<rt>Inventory</rt></ruby>：这个文件包含有关管理的服务器的信息。
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* <ruby>任务<rt>Task</rt></ruby>：每个剧本都有大量的任务。任务在指定机器上依次执行（一个主机或多个主机）。
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* <ruby>模块<rt>Module</rt></ruby>： 模块是一个代码单元，用于从客户端节点收集信息。
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* <ruby>角色<rt>Role</rt></ruby>：角色是根据已知文件结构自动加载一些变量文件、任务和处理程序的方法。
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* <ruby>动作<rt>Play</rt></ruby>：每个剧本含有大量的动作，一个动作从头到尾执行一个特定的自动化。
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* <ruby>处理程序<rt>Handler</rt></ruby>： 它可以帮助你减少在剧本中的重启任务。处理程序任务列表实际上与常规任务没有什么不同，更改由通知程序通知。如果处理程序没有收到任何通知，它将不起作用。
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### 基本的剧本是怎样的？
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下面是一个剧本的模板：
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```
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--- [YAML 文件应该以三个破折号开头]
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- name: [脚本描述]
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hosts: group [添加主机或主机组]
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become: true [如果你想以 root 身份运行任务，则标记它]
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tasks: [你想在任务下执行什么动作]
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- name: [输入模块选项]
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module: [输入要执行的模块]
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module_options-1: value [输入模块选项]
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module_options-2: value
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.
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module_options-N: value
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```
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### 如何理解 Ansible 的输出
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Ansible 剧本的输出有四种颜色，下面是具体含义：
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* **绿色**：`ok` 代表成功，关联的任务数据已经存在，并且已经根据需要进行了配置。
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* **黄色**：`changed` 指定的数据已经根据任务的需要更新或修改。
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* **红色**：`FAILED` 如果在执行任务时出现任何问题，它将返回一个失败消息，它可能是任何东西，你需要相应地修复它。
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* **白色**：表示有多个参数。
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为此，创建一个剧本目录，将它们都放在同一个地方。
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```
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$ sudo mkdir /etc/ansible/playbooks
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```
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### 剧本-1：在 RHEL 系统上安装 Apache Web 服务器
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这个示例剧本允许你在指定的目标机器上安装 Apache Web 服务器：
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```
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$ sudo nano /etc/ansible/playbooks/apache.yml
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---
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- hosts: web
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become: yes
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name: "Install and Configure Apache Web server"
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tasks:
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- name: "Install Apache Web Server"
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yum:
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name: httpd
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state: latest
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- name: "Ensure Apache Web Server is Running"
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service:
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name: httpd
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state: started
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```
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```
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$ ansible-playbook apache1.yml
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```
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![][3]
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### 如何理解 Ansible 中剧本的执行
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使用以下命令来查看语法错误。如果没有发现错误，它只显示剧本文件名。如果它检测到任何错误，你将得到一个如下所示的错误，但内容可能根据你的输入文件而有所不同。
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```
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$ ansible-playbook apache1.yml --syntax-check
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ERROR! Syntax Error while loading YAML.
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found a tab character that violate indentation
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The error appears to be in '/etc/ansible/playbooks/apache1.yml': line 10, column 1, but may
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be elsewhere in the file depending on the exact syntax problem.
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The offending line appears to be:
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state: latest
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^ here
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There appears to be a tab character at the start of the line.
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YAML does not use tabs for formatting. Tabs should be replaced with spaces.
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For example:
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- name: update tooling
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vars:
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version: 1.2.3
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# ^--- there is a tab there.
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Should be written as:
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- name: update tooling
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vars:
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version: 1.2.3
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# ^--- all spaces here.
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```
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或者，你可以使用这个 URL [YAML Lint][4] 在线检查 Ansible 剧本内容。
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执行以下命令进行“演练”。当你运行带有 `--check` 选项的剧本时，它不会对远程机器进行任何修改。相反，它会告诉你它将要做什么改变但不是真的执行。
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```
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$ ansible-playbook apache.yml --check
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PLAY [Install and Configure Apache Webserver] ********************************************************************
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TASK [Gathering Facts] *******************************************************************************************
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ok: [node2.2g.lab]
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ok: [node1.2g.lab]
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TASK [Install Apache Web Server] *********************************************************************************
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changed: [node2.2g.lab]
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changed: [node1.2g.lab]
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TASK [Ensure Apache Web Server is Running] ***********************************************************************
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changed: [node1.2g.lab]
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changed: [node2.2g.lab]
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PLAY RECAP *******************************************************************************************************
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node1.2g.lab : ok=3 changed=2 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
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node2.2g.lab : ok=3 changed=2 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
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```
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如果你想要知道 ansible 剧本实现的详细信息，使用 `-vv` 选项，它会展示如何收集这些信息。
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```
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$ ansible-playbook apache.yml --check -vv
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ansible-playbook 2.9.2
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config file = /etc/ansible/ansible.cfg
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configured module search path = ['/home/daygeek/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
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ansible python module location = /usr/lib/python3.8/site-packages/ansible
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executable location = /usr/bin/ansible-playbook
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python version = 3.8.1 (default, Jan 8 2020, 23:09:20) [GCC 9.2.0]
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Using /etc/ansible/ansible.cfg as config file
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PLAYBOOK: apache.yml *****************************************************************************************************
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1 plays in apache.yml
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PLAY [Install and Configure Apache Webserver] ****************************************************************************
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TASK [Gathering Facts] ***************************************************************************************************
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task path: /etc/ansible/playbooks/apache.yml:2
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ok: [node2.2g.lab]
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ok: [node1.2g.lab]
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META: ran handlers
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TASK [Install Apache Web Server] *****************************************************************************************
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task path: /etc/ansible/playbooks/apache.yml:6
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changed: [node2.2g.lab] => {"changed": true, "msg": "Check mode: No changes made, but would have if not in check mod
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e", "rc": 0, "results": ["Installed: httpd"]}
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changed: [node1.2g.lab] => {"changed": true, "changes": {"installed": ["httpd"], "updated": []}, "msg": "", "obsolet
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es": {"urw-fonts": {"dist": "noarch", "repo": "@anaconda", "version": "2.4-16.el7"}}, "rc": 0, "results": []}
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TASK [Ensure Apache Web Server is Running] *******************************************************************************
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task path: /etc/ansible/playbooks/apache.yml:10
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changed: [node1.2g.lab] => {"changed": true, "msg": "Service httpd not found on host, assuming it will exist on full run"}
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changed: [node2.2g.lab] => {"changed": true, "msg": "Service httpd not found on host, assuming it will exist on full run"}
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META: ran handlers
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META: ran handlers
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PLAY RECAP ***************************************************************************************************************
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node1.2g.lab : ok=3 changed=2 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
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node2.2g.lab : ok=3 changed=2 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
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```
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### 剧本-2：在 Ubuntu 系统上安装 Apache Web 服务器
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这个示例剧本允许你在指定的目标节点上安装 Apache Web 服务器。
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```
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$ sudo nano /etc/ansible/playbooks/apache-ubuntu.yml
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---
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- hosts: web
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become: yes
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name: "Install and Configure Apache Web Server"
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tasks:
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- name: "Install Apache Web Server"
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yum:
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name: apache2
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state: latest
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- name: "Start the Apache Web Server"
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service:
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name: apaceh2
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state: started
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- name: "Enable mod_rewrite module"
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apache2_module:
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name: rewrite
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state: present
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notify:
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- start apache
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handlers:
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- name: "Ensure Apache Web Server is Running"
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service:
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name: apache2
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state: restarted
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enabled: yes
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```
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### 剧本-3：在 Red Hat 系统上安装软件包列表
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这个示例剧本允许你在指定的目标节点上安装软件包。
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**方法-1：**
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```
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$ sudo nano /etc/ansible/playbooks/packages-redhat.yml
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---
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- hosts: web
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become: yes
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name: "Install a List of Packages on Red Hat Based System"
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tasks:
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- name: "Installing a list of packages"
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yum:
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name:
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- curl
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- httpd
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- nano
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- htop
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```
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**方法-2：**
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```
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$ sudo nano /etc/ansible/playbooks/packages-redhat-1.yml
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---
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- hosts: web
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become: yes
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name: "Install a List of Packages on Red Hat Based System"
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tasks:
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- name: "Installing a list of packages"
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yum: name={{ item }} state=latest
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with_items:
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- curl
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- httpd
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- nano
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- htop
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```
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**方法-3：使用数组变量**
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```
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$ sudo nano /etc/ansible/playbooks/packages-redhat-2.yml
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---
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- hosts: web
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become: yes
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name: "Install a List of Packages on Red Hat Based System"
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vars:
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packages: [ 'curl', 'git', 'htop' ]
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tasks:
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- name: Install a list of packages
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yum: name={{ item }} state=latest
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with_items: "{{ packages }}"
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```
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### 剧本-4：在 Linux 系统上安装更新
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这个示例剧本允许你在基于 Red Hat 或 Debian 的 Linux 系统上安装更新。
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```
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$ sudo nano /etc/ansible/playbooks/security-update.yml
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---
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- hosts: web
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become: yes
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name: "Install Security Update"
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tasks:
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- name: "Installing Security Update on Red Hat Based System"
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yum: name=* update_cache=yes security=yes state=latest
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when: ansible_facts['distribution'] == "CentOS"
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- name: "Installing Security Update on Ubuntu Based System"
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apt: upgrade=dist update_cache=yes
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when: ansible_facts['distribution'] == "Ubuntu"
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```
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--------------------------------------------------------------------------------
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via: https://www.2daygeek.com/ansible-playbooks-quick-start-guide-with-examples/
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作者：[Magesh Maruthamuthu][a]
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选题：[lujun9972][b]
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译者：[MjSeven](https://github.com/MjSeven)
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校对：[wxy](https://github.com/wxy)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]: https://www.2daygeek.com/author/magesh/
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[b]: https://github.com/lujun9972
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[1]: https://linux.cn/article-13142-1.html
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[2]: https://linux.cn/article-13163-1.html
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[3]: https://www.2daygeek.com/wp-content/uploads/2020/01/ansible-playbook-structure-flow-chart-explained.png
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[4]: http://www.yamllint.com/
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