Ansible script--- playbook script

(1) Tasks : tasks, that is, calling ansible templates through tasks to organize multiple operations to run in a playbook
(2) Variables : variables
(3) Templates : templates
(4) Handlers : processors, when the changed status condition is met , (notify) triggers the execution of the operation
(5) Roles : roles

Two: Cases

1. Remotely install http service

vim test1.yaml
---     #yaml文件以---开头，以表明这是一个yaml文件，可省略
- name: first play     #定义一个play的名称，可省略
  gather_facts: false    #设置不进行facts信息收集，这可以加快执行速度，可省略
  hosts: webservers    #指定要执行任务的被管理主机组，如多个主机组用冒号分隔
  remote_user: root    #指定被管理主机上执行任务的用户
  tasks:     #定义任务列表，任务列表中的各任务按次序逐个在hosts中指定的主机上执行
   - name: test connection    #自定义任务名称
     ping:     #使用 module: [options] 格式来定义一个任务
   - name: disable selinux
     command: '/sbin/setenforce 0'    #command模块和shell模块无需使用key=value格式
     ignore_errors: True     #如执行命令的返回值不为0，就会报错，tasks停止，可使用ignore_errors忽略失败的任务
   - name: disable firewalld
     service: name=firewalld state=stopped    #使用 module: options 格式来定义任务，option使用key=value格式
   - name: install httpd
     yum: name=httpd state=latest
   - name: install configuration file for httpd
     copy: src=/opt/httpd.conf dest=/etc/httpd/conf/httpd.conf    #这里需要一个事先准备好的/opt/httpd.conf文件
     notify: "restart httpd"    #如以上操作后为changed的状态时，会通过notify指定的名称触发对应名称的handlers操作
   - name: start httpd service
     service: enabled=true name=httpd state=started
  handlers:     #handlers中定义的就是任务，此处handlers中的任务使用的是service模块
   - name: restart httpd    #notify和handlers中任务的名称必须一致
     service: name=httpd state=restarted
##Ansible在执行完某个任务之后并不会立即去执行对应的handler，而是在当前play中所有普通任务都执行完后再去执行handler，这样的好处是可以多次触发notify，但最后只执行一次对应的handler，从而避免多次重启。

//运行playbook
ansible-playbook test01.yaml
//补充参数：
-k（–ask-pass）：用来交互输入ssh密码
-K（-ask-become-pass）：用来交互输入sudo密码
-u：指定用户
ansible-playbook test1.yaml --syntax-check    #检查yaml文件的语法是否正确
ansible-playbook test1.yaml --list-task       #检查tasks任务
ansible-playbook test1.yaml --list-hosts      #检查生效的主机
ansible-playbook test1.yaml --start-at-task='install httpd'     #指定从某个task开始运行

2. Define and reference variables

- name: second play
  hosts: dbservers
  remote_user: root
  vars:                 #定义变量
   - groupname: mysql   #格式为 key: value
   - username: nginx
  tasks:
   - name: create group
     group: name={
   
   {groupname}} system=yes gid=306    #使用 {
   
   {key}} 引用变量的值
   - name: create user
     user: name={
   
   {username}} uid=306 group={
   
   {groupname}} 
   - name: copy file
     copy: content="{
   
   {ansible_default_ipv4}}" dest=/opt/vars.txt    #在setup模块中可以获取facts变量信息


ansible-playbook test1.yaml -e "username=nginx"     #在命令行里定义变量

3. Specify the remote host sudo to switch users

---
- hosts: dbservers
remote_user: zhangsan
become: yes #2.6版本以后的参数，之前是sudo，意思为切换用户运行
become_user: root #指定sudo用户为root
执行playbook时：ansible-playbook test3.yml -K <密码>

4. When condition judgment

在Ansible中，提供的唯一一个通用的条件判断是when指令，当when指令的值为true时，则该任务执行，否则不执行该任务。

//when一个比较常见的应用场景是实现跳过某个主机不执行任务或者只有满足条件的主机执行任务
vim test2.yaml
---
- hosts: all
  remote_user: root
  tasks:
   - name: shutdown host 
     command: /sbin/shutdown -r now
     when: ansible_default_ipv4.address == "192.168.231.110"      #when指令中的变量名不需要手动加上 {
   
   {}}
或 
     when: inventory_hostname == "<主机名>"
	
ansible-playbook test2.yaml

5. Iteration

Ansible provides many loop structures, generally named with_items, which are equivalent to loop loops.

vim test3.yaml
---
- name: play1
  hosts: dbservers
  gather_facts: false
  tasks: 
    - name: create file
      file:
        path: "{
   
   {item}}"
        state: touch
      with_items: [ /opt/a, /opt/b, /opt/c, /opt/d ]


- name: play2
  hosts: dbservers
  gather_facts: false		
  vars:
    test:
    - /tmp/test1
    - /tmp/test2
    - /tmp/test3
    - /tmp/test4
  tasks: 
    - name: create directories
      file:
        path: "{
   
   {item}}"
        state: directory
      with_items: "{
   
   {test}}"
		
- name: play3
  hosts: dbservers
  gather_facts: false
  tasks:
    - name: add users
      user: name={
   
   {item.name}} state=present groups={
   
   {item.groups}}
      with_items:
        - name: test1
          groups: wheel
        - name: test2
          groups: root
或
      with_items:
        - {name: 'test1', groups: 'wheel'}
        - {name: 'test2', groups: 'root'}

ansible-playbook test3.yaml

Three: Templates module

Jinja is a Python-based template engine. The Template class is an important component of Jinja. It can be regarded as a compiled template file, used to generate target text and pass Python variables to the template to replace the tags in the template.

1. First prepare a template file with .j2 as the suffix and set the referenced variables.

cp /etc/httpd/conf/httpd.conf /opt/httpd.conf.j2

vim /opt/httpd.conf.j2
Listen {
   
   {http_port}}				#42行，修改
ServerName {
   
   {server_name}}			#95行，修改
DocumentRoot "{
   
   {root_dir}}"          #119行，修改

2. Modify the host manifest file and use host variables to define a variable with the same name but different values.

vim /etc/ansible/hosts       
[webservers]
192.168.231.102 http_port=192.168.231.100:80 server_name=www.accp.com:80 root_dir=/etc/httpd/htdocs

[dbservers]
192.168.231.110 http_port=192.168.231.100:80 server_name=www.benet.com:80 root_dir=/etc/httpd/htdocs

3. Write playbook

vim apache.yaml
---
- hosts: all
  remote_user: root
  vars:
    - package: httpd
    - service: httpd
  tasks:
    - name: install httpd package
      yum: name={
   
   {package}} state=latest
    - name: install configure file
      template: src=/opt/httpd.conf.j2 dest=/etc/httpd/conf/httpd.conf     #使用template模板
      notify:
        - restart httpd
    - name: create root dir
	  file: path=/etc/httpd/htdocs state=directory
    - name: start httpd server
      service: name={
   
   {service}} enabled=true state=started
  handlers:
    - name: restart httpd
      service: name={
   
   {service}} state=restarted

ansible-playbook apache.yaml

Four: tags module

1. Introduction to tags

You can define "tags" for one or more tasks in a playbook. When executing this playbook, use the --tags option with the ansible-playbook command to run only the specified tasks.
The playbook also provides a special tags for always. The function is that when always is used as the task of tags, no matter which tags are executed, the tags defined with always will be executed.

2. Case study

im webhosts.yaml
---
- hosts: webservers
  remote_user: root
  tasks:
    - name: Copy hosts file
      copy: src=/etc/hosts dest=/opt/hosts
      tags:
      - only     #可自定义
    - name: touch file
      file: path=/opt/testhost state=touch
	  tags:
	  - always    #表示始终要运行的代码

ansible-playbook webhosts.yaml --tags="only"

vim dbhosts.yaml
---
- hosts: dbservers
  remote_user: root
  tasks:
    - name: Copy hosts file
      copy: src=/etc/hosts dest=/opt/hosts
      tags:
        - only
    - name: touch file
      file: path=/opt/testhost state=touch


ansible-playbook dbhosts.yaml --tags="only"
//分别去两台被管理主机上去查看文件创建情况

Five: Roles module

1. Introduction to Roles module

Roles are used to organize playbooks hierarchically and structurally. Roles can automatically load variable files, tasks, handlers, etc. according to the hierarchical structure. To use roles, you only need to use the include directive in the playbook to introduce them.
Simply put, roles are a mechanism that places variables, files, tasks, templates, and processors in separate directories and can easily include them. Roles are generally used in scenarios where services are built based on hosts, but they can also be used in scenarios such as building daemons. Mainly used in scenarios where code reuse is high.

If we now have three managed hosts, the first one needs to be configured as httpd, the second one needs to be configured as a haproxy server, and the third one needs to be configured as a MySQL (mariadb) server. How do we define playbook?
The first play is used on the first host to build httpd, and the second play is used on the second host to build haproxy. These play definitions are troublesome in the playbook, and are not conducive to modular calls or multiple calls in the future. For example, if a host is added later, this third host is both an httpd server and a haproxy server. We can only write the third play, which says to install httpd and haproxy. In this way, the code in the playbook is repeated.
In order to avoid code duplication, you can define a role called httpd, a second role called haproxy, and use roles to implement code repeated calls.

2. Directory structure of roles

cd /etc/ansible/
tree roles/
roles/
├── web/    #相当于 playbook 中的 每一个 play 主题
│   ├── files/
│   ├── templates/
│   ├── tasks/
│   ├── handlers/
│   ├── vars/
│   ├── defaults/
│   └── meta/
└── db/
    ├── files/
    ├── templates/
    ├── tasks/
    ├── handlers/
    ├── vars/
    ├── defaults/
    └── meta/

Explanation of the meaning of each directory in roles
● files
are used to store files called by the copy module or script module.

●templates
is used to store jinjia2 templates. The template module will automatically search for jinjia2 template files in this directory.

●tasks
This directory should contain a main.yml file, which is used to define the task list of this role. This file can use include to include other task files located in this directory.

●handlers
This directory should contain a main.yml file, which is used to define the actions to be performed when conditions are triggered in this role.

●vars
This directory should contain a main.yml file to define the variables used by this role.

●defaults
This directory should contain a main.yml file, which is used to set default variables for the current role. These variables have the lowest priority of all available variables and can be easily overridden by any other variable. Therefore, we generally do not define variables here in production.

●meta
This directory should contain a main.yml file to define the metadata information of this role and its dependencies.

3. Use roles in a playbook

(1) Create a directory named after roles

mkdir /etc/ansible/roles/ -p    #yum装完默认就有

创建全局变量目录（可选）
mkdir /etc/ansible/group_vars/ -p
touch /etc/ansible/group_vars/all     #文件名自己定义，引用的时候注意

(2) Create directories named after each role in the roles directory.

mkdir /etc/ansible/roles/httpd
mkdir /etc/ansible/roles/mysql

在每个角色命名的目录中分别创建files、handlers、tasks、templates、meta、defaults和vars目录，用不到的目录可以创建为空目录
mkdir /etc/ansible/roles/httpd/{files,templates,tasks,handlers,vars,defaults,meta}
mkdir /etc/ansible/roles/mysql/{files,templates,tasks,handlers,vars,defaults,meta}

在每个角色的 handlers、tasks、meta、defaults、vars 目录下创建 main.yml 文件，千万不能自定义文件名
touch /etc/ansible/roles/httpd/{defaults,vars,tasks,meta,handlers}/main.yml
touch /etc/ansible/roles/mysql/{defaults,vars,tasks,meta,handlers}/main.yml

(3) Modify the site.yml file to call different roles for different hosts

vim /etc/ansible/site.yml
---
- hosts: webservers
  remote_user: root
  roles:
     - httpd
- hosts: dbservers
  remote_user: root
  roles:
     - mysql

(4) Run ansible-playbook

cd /etc/ansible
ansible-playbook site.yml

4. Write lnmp

mkdir /etc/ansible/roles/httpd/{files,templates,tasks,handlers,vars,defaults,meta} -p
mkdir /etc/ansible/roles/mysql/{files,templates,tasks,handlers,vars,defaults,meta} -p
mkdir /etc/ansible/roles/php/{files,templates,tasks,handlers,vars,defaults,meta} -p

touch /etc/ansible/roles/httpd/{defaults,vars,tasks,meta,handlers}/main.yml
touch /etc/ansible/roles/mysql/{defaults,vars,tasks,meta,handlers}/main.yml
touch /etc/ansible/roles/php/{defaults,vars,tasks,meta,handlers}/main.yml

(1) Write httpd module

写一个简单的tasks/main.yml
vim /etc/ansible/roles/httpd/tasks/main.yml
- name: install apache
  yum: name={
   
   {pkg}} state=latest
- name: start apache
  service: enabled=true name={
   
   {svc}} state=started
 
//定义变量：可以定义在全局变量中，也可以定义在roles角色变量中，一般定义在角色变量中
vim /etc/ansible/roles/httpd/vars/main.yml
pkg: httpd
svc: httpd

(2) Write mysql module

vim /etc/ansible/roles/mysql/tasks/main.yml
- name: install mysql
  yum: name={
   
   {pkg}} state=latest
- name: start mysql
  service: enabled=true name={
   
   {svc}} state=started
  
vim /etc/ansible/roles/mysql/vars/main.yml
pkg:
  - mariadb
  - mariadb-server
svc: mariadb

(3)Write php module

vim /etc/ansible/roles/php/tasks/main.yml
- name: install php
  yum: name={
   
   {pkg}} state=latest
- name: start php-fpm
  service: enabled=true name={
   
   {svc}} state=started

vim /etc/ansible/roles/php/vars/main.yml
pkg:
  - php
  - php-fpm
svc: php-fpm

(4) Write examples of roles

vim /etc/ansible/site.yml
---
- hosts: webservers
  remote_user: root
  roles:
   - httpd
   - mysql
   - php


cd /etc/ansible
ansible-playbook site.yml