Ansible varialbes

1. What is a variable?

To a fixed string, not a fixed value indicates version: 1.12

2. Define the variables?

• 1. Define the variables in the playbook?

  • vars keyword

  [root@manager project1]# cat f2.yml 
  - hosts: webservers
    vars:
      - file_name: playbook_vars
  
    tasks:
      - name: Create New File
        file:
          path: /tmp/{{ file_name }}
          state: touch

  • vars_file belongs sharing manner

  

  [root@manager project1]# cat vars_file.yml 
  web_packages: httpd
  ftp_packages: vsftpd
  
  [root@manager project1]# cat f2.yml 
  - hosts: webservers
    vars:
      - file_name: playbook_vars
  
   #调用共享vars_file文件,只不过刚好文件名叫vars_file
    vars_files: ./vars_file.yml
  
    tasks:
      - name: Create New File
        file:
          path: /tmp/{{ file_name }}
          state: touch
  
      - name: Installed Packages {{ web_packages }}
        yum:
          name: "{{ web_packages }}"
          state: present

• 2. Define the host variables in inventory list?

  • 1. The list of documents directly define the hosts file definition -

  [webservers]
  172.16.1.7
  172.16.1.8 
  [webservers:vars]
  file_name=hostsfile_group_vars

  • 2. Create a directory hosts_vars group_vars

  [root@manager project1]# mkdir hosts_vars #单个主机
  [root@manager project1]# mkdir group_vars #主机组
  
  
  #1.单个主机定义和使用方式 (host_vars能分别对不同的主机定义变量)
  [root@manager project1]# cat host_vars/172.16.1.7 
  host_vars_name: 172.16.1.7
  
  [root@manager project1]# cat host_vars/172.16.1.8 
  host_vars_name: 172.16.1.8
  
  [root@manager project1]# cat f4.yml 
  - hosts: webservers
  
    tasks:
      - name: Create New File
        file:
          path: /opt/{{ host_vars_name }}
          state: touch
  
  #2.针对主机组定义的方式 
  #给指定的webserver组设定变量.其他组主机无法使用该变量
  [root@manager project1]# cat group_vars/webservers 
  group_host_vars: webservers
  
  [root@manager project1]# cat f5.yml 
  - hosts: webservers
    tasks:
      - name: Create New File {{ group_host_vars }}
        file:
          path:  /opt/{{ group_host_vars }}
          state: touch
  
  
  #3.针对主机组定义的方式  (给所有的主机和主机组设定变量)
  [root@manager project1]# cat group_vars/all 
  group_host_vars: all
  
  [root@manager project1]# cat f5.yml 
  - hosts: webservers
    tasks:
      - name: Create New File {{ group_host_vars }}
        file:
          path:  /opt/{{ group_host_vars }}
          state: touch

• 3. See the definition of external variables pass? -E

[root@manager project1]# ansible-playbook -i hosts f6.yml  -e "web_vars=123"

3. Variable conflict, the priority?

6.定义相同的变量不同的值，来测试变量的优先级。操作步骤如下   file_name:
  1）在plabook中定义vars变量
  2）在playbook中定义vars_files变量
  3）在inventory主机定义变量
  4）在inventory主机组定义变量
  5）在host_vars中定义变量
  6）在group_vars中定义变量  组      all组
  7）通过执行命令传递变量
 
 
优先级测试:
外置传入参数优先级最高 ---> playbook ( vars_files(共享)--->vars(私有) )  
---> host_vars  --> group_vars/group_name ---> group_vars/all

4. Variable registered?

[root@manager project1]# cat f8.yml 
- hosts: webservers
  tasks:
        # System_Status=$(netstat -lntp)
    - name: Get Network Status
      shell: netstat -lntp | grep "nginx"
      register: System_Status

        # echo "$System_Status"
    - name: Debug output Variables
      debug:
        msg: "{{ System_Status.stdout_lines }}"

5.facts variable?

#1.根据主机的cpu信息,生成不同的配置.
    A: 1核心    work_process 1;
    B: 2核心    work_process 2;
    
#2.根据主机名称设定不同配置文件
    zabbix_agent
        Server:   ===> 指向172.16.1.61
        Hostname:      web01   web02

[root@manager project1]# cat ./file/zabbix_agent.conf.j2 
Server={{ zabbix_server_ip }}
ServerActive={{ zabbix_server_ip }}
Hostname={{ ansible_hostname }}

[root@manager project1]# cat f11.yml 
- hosts: webservers
  vars:
    - zabbix_server_ip: 172.16.1.61
  tasks:
    - name: Configure zabbix-agent.conf
      template:
        src: ./file/zabbix_agent.conf.j2
        dest: /tmp/zabbix-agent.conf
        
        
#3.根据主机的内存生成不同的配置文件,memcached
[root@manager project1]# cat f12.yml 
- hosts: webservers
  tasks:
    - name: Installed Memcached Server
      yum:
        name: memcached
        state: present

    - name: Configure Memcached Server
      template:
        src: ./file/memcached.j2
        dest: /etc/sysconfig/memcached
      notify: Restart Memcached Server

    - name: System Memcached Server
      systemd:
        name: memcached
        state: started
        enabled: yes

  handlers:
    - name: Restart Memcached Server
      systemd:
        name: memcached
        state: restarted

[root@manager project1]# cat file/memcached.j2 
PORT="11211"
USER="memcached"
MAXCONN="1024"
CACHESIZE="{{ ansible_memtotal_mb //2 }}"
OPTIONS=""


1.根据cpu
2.根据内存
3.根据主机名
4.Redis配置文件     bind本地地址
5.操作系统不统一

        变量可以进行运算  + - * // 
        
        
        
        
#1.定义变量
    playbook
        vars            私有
        vars_files      共享
    inventory
        host_vars   
        group_vars
            group_vars/group_name
            group_vars/all
    外置传参
        -e
#2.测试优先级
    在不改变playbook变量的情况下,使用新的值测试.

#3.变量注册register
    1.将任务执行的结果存储至特定的变量中
    2.可以使用debug模块将变量进行打印输出
    
    python: 字典
    json 格式化数据
    {
        k1: v1
        k2: v2
    }
#4.facts 

[root@manager project1]# cat f13.yml 
- hosts: webservers
  tasks:
    - name: RANDOM
      shell:  echo "$RANDOM"
      register: System_SJ

    - name: Debug 
      debug:
        msg: "web_{{ System_SJ.stdout }}"

#1.提取facts变量中的IP地址   mac地址  UUID 等等  只要唯一
    ansible_default_ipv4.address
[root@manager project1]# cat f14.yml 
- hosts: webservers
  tasks:

    - name: Debug 
      debug:
        msg: "web_{{ ansible_default_ipv4.address }}"