Ansible是一个自动化运维工具，基于Python开发，实现了批量系统配置、批量程序部署、批量运行命令等功能。Ansible是基于模块(module)和剧本(playbook)工作。Ansible可以用于管理Windows服务器，不需要安装agent客户端，而是利用Windows自带的PowerShell管理Windows服务器。
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随着IT基础设施的日益复杂化，自动化运维变得越来越重要，Ansible作为一款强大的开源工具，已经成为许多企业和组织实现自动化运维的首选，本文将从Ansible的基本概念、安装与配置、模块使用以及实战案例等方面，全面介绍如何使用Ansible实现自动化运维。
Ansible基本概念
1、1 Ansible简介
Ansible是一个开源的IT自动化工具，用于配置管理、应用部署、任务执行和多节点协调，通过使用Ansible,可以简化IT基础设施的管理，提高工作效率。
1、2 Ansible工作原理
Ansible通过SSH协议在远程主机上执行命令，支持多种操作系统，如Linux、Windows、Mac OS等，Ansible的核心组件包括：SSH客户端(ansible)、SSH服务器(OpenSSH或WinRM)以及任务处理器(如shell、python等)。
Ansible安装与配置
2、1 安装Ansible
在官方网站下载最新版本的Ansible,解压缩后进入解压目录，执行以下命令进行安装：
sudo apt-get update sudo apt-get install software-properties-common sudo apt-add-repository --yes --update ppa:ansible/ansible sudo apt-get install ansible
2、2 配置Ansible
在Ansible的安装目录下创建一个名为inventory的文件夹，用于存放主机清单文件，在inventory文件夹下创建一个名为hosts的文件，定义需要管理的主机及其相关信息。
[web_servers] 192、168.1.100 ansible_user=root ansible_ssh_pass=your_password [database_servers] 192、168.1.101 ansible_user=root ansible_ssh_pass=your_password
Ansible模块使用
3、1 基础模块
Ansible提供了一些基础模块，如command、copy、file等，用于在远程主机上执行命令或操作文件。
- name: Ensure Nginx is installed and running package: nginx state=present become: yes
3、2 循环模块
Ansible还提供了循环模块，如with_items、loop,用于遍历列表或迭代器。
- name: Install packages on multiple servers
hosts: web_servers
tasks:
- name: Install Nginx on each server
package: nginx state=present
become: yes3、3 条件模块
Ansible的条件模块，如when、unless,用于根据条件执行任务。
- name: Start Nginx only if it's not already running service: nginx state=started when=not nginx.service is running in group 'www-data' become=yes
实战案例
4、1 部署Nginx服务器负载均衡示例
- name: Ensure Nginx is installed and running on all servers for load balancing
hosts: web_servers loop: "{{ range(2|int) | random}}" become: yes
tasks:
- name: Install Nginx on each server for load balancing purposes only if it's not already installed or running as a result of the previous task withstate=absent. This ensures that no other process will interfere with the installation or start of the service. If it's already installed or running, then the task will be skipped and the next iteration will use an updated list of servers. Thestate=absent option also ensures that the service starts after the configuration has been applied to the target host. Thebecome=yes option allows the user to run this task with root privileges. Note that this task does not include any configuration for the load balancer itself; that would be done separately. Thenotify keyword can be used to trigger another playbook or task once this task has completed successfully on one or more servers. This can be useful for performing additional actions or checks after the load balancer has been deployed. For example, you might want to check that the load balancer is working by sending a request to one of the backend servers and checking the response time. You could do this by adding await_for task with a timeout value after this task completes successfully on one or more servers usingnotify. This task will wait for a certain amount of time (specified by thetimeout parameter) for the load balancer to respond to requests from the client before timing out and failing the playbook or task. If the load balancer responds within the specified timeout period, then the playbook or task will continue to run to completion without failing. If it doesn't respond within the timeout period, then the playbook or task will fail and notify the user of the failure using thefailed_when keyword. Thefailed_when keyword takes a boolean expression that returns true if the condition is met and false otherwise. In this case, we're using an expression that checks whether the response time to requests from the client exceeds a certain threshold (specified by thetimeout parameter). If it does, then we know that the load balancer is not working properly and we should fail the playbook or task so that we can investigate further. Thenotify keyword can also be used to trigger another playbook or task that performs some action when this task fails. For example, you might want to send an email notification to an administrator when this task fails due to an error message indicating that there was a problem starting or stopping the load balancer service on one or more servers. You could do this by adding afail_handler task with a command that sends an email using a tool likesendmail. Thefail_handler task takes a command as its argument and executes that command when this task fails or times out without completing successfully. In this case, we're sending an email usingsendmail, which requires specifying a recipient address and a subject line for the email message. You can specify these values using variables that are defined in a separate variable file or environment variable. Thesendmail command takes two arguments: the recipient address and the message body. In this case, we're using an template variable calledemail_body, which contains a placeholder for the message body text that we want to send in the email message. We can replace this placeholder with actual text using Jinja2 syntax by setting up a template file with placeholders for different parts of the message body text and including that file in our playbook or task using thetemplate keyword with a filename parameter. Once we have replaced all of the placeholders with actual text, we can pass this file tosendmail as its second argument along with the recipient address and subject line to generate a complete email message that we can send usingsendmail.
