ansible-playbook变量

Posted 2021-02-18 lailaoban

今日内容Ansible Playbook变量解析

# 1.变量概述

变量提供了便捷的方式来管理ansible项目中的动态值。比如zabbix-3.14.15可能后期会反复的使用 到这个版本的值，那么如果将此值设置为变量，后续使用和修改都将变得非常方便。这样可以简化项目的创建和维护

定义变量分为如下的三种方式

（1）通过命令行进行定义变量

（2）在play文件中进行定义变量

（3）通过inventory在主机组或单个主机中设置变量

如果定义的变量出现重复，且造成冲突，优先级如下：

1.命令行定义的变量高于->play文件定义的变量->高于->inventory文件定义的变量

# 2.变量的定义

2.1playbook 变量可以通过多种方式进行定义，最简单的方式就是在playbook的开头通过vars进行定义变量

```html
#安装两个软件包使用变量方式
[root@manager ansible_lianxi-5.18]# cat var1.yml
- hosts: webservers
vars:
- web_packages: httpd
- ftp_packages: vsftpd
tasks:
- name: installed rpm packages "{{web_packages}}" "{{ftp_packages}}"
yum:
name:
- "{{web_packages}}"
- "{{ftp_packages}}"
state: present

```

2.2也可以在playbook中使用vars_file指定的文件作为变量文件，好处其他的playbook也可以调用变量

```HTML
[root@manager ansible_lianxi-5.18]# cat test.yml
web_packages: httpd
ftp_packages: vsftpd
[root@manager ansible_lianxi-5.18]# cat var2.yml
- hosts: webservers
vars_files: test.yml

tasks:
- name: install rpm packages "{{web_packages}}" "{{ftp_packages}}"
yum:
name:
- "{{web_packages}}"
- "{{ftp_packages}}"
state: present
```

2.3在inventory中定义变量，主机变量优先级高于主机组变量（不推荐使用）

```HTML
[root@manager ansible_lianxi-5.18]# cat hosts
[webservers]

172.16.1.7
172.16.1.8
[webservers:vars]
filename=group_vars
[db]
172.16.1.51
[lb]
172.16.1.5
[root@manager ansible_lianxi-5.18]# cat p3.yml
- hosts: webservers
tasks:
- name: create file "{{filename}}"
file:
path: /tmp/{{filename}}
state: touch
```

2.4.更好的方式是在ansible的项目目录中创建额外的两个变量目录，分别是host_vars和group_vars

```HTML
[root@manager ansible_lianxi-5.18]# mkdir host_vars
[root@manager ansible_lianxi-5.18]# mkdir group_vars
[root@manager ansible_lianxi-5.18]# cat group_vars/webservers
web_packages: wget
ftp_packages: tree
[root@manager ansible_lianxi-5.18]# cat var4.yml
- hosts: webservers
tasks:
- name: install rpm packages "{{web_packages}}" "{{ftp_packages}}"
yum:
name:
- "{{web_packages}}"
- "{{ftp_packages}}"
state: present
注意：系统提供了特殊的组，all，也就说在group_vars目录下创建一个all文件，定义变量对所有的主机都生效
[root@manager ansible_lianxi-5.18]# cat group_vars/all
web_packages: nfs-utils
ftp_packages: rsync
[root@manager ansible_lianxi-5.18]# cat var5.yml
- hosts: db
tasks:
- name: install rpm packages "{{web_packages}}" "{{ftp_packages}}"
yum:
name:
- "{{web_packages}}"
- "{{ftp_packages}}"
state: present

```

2.5通过命令的方式进行定义变量

```HTML
[root@manager ansible_variables]# cat var6.yml
- hosts: webservers
tasks:
- name: Install Rpm Packages "{{ test_packages }}"
yum:
name:
- "{{ test_packages }}"
state: present

[root@manager ansible_variables]# ansible-playbook var6.yml -e "test_packages=sl"

```

2.6变量优先级测试

命令行变量--play中的vars_files---play中的vars变量---host_vars中定义的变量--group_vars/组名---group_vars/all

```HTML
设定同一个变量，不同的值，去测试，看谁优先被使用。
1）在plabook中定义vars变量
2）在playbook中定义vars_files变量
3）在host_vars中定义变量
4）在group_vars中定义变量
5）通过执行命令传递变量
变量的查找优先级：
1.外置传参 -e
2.playbook
vars_files
vars
3.host_vars
4.group_vars/组名
4.group_vars/all
```

2.7 案例演示nfs服务端和nfs客户端

```HTML
[root@manager ansible_lianxi-5.18]# cat group_vars/all
share_dir: /data4
[root@manager ansible_lianxi-5.18]# cat exports.j2
{{share_dir}} 172.16.1.0/24(rw,all_squash,anonuid=666,anongid=666)
[root@manager ansible_lianxi-5.18]# cat var8.yml
- hosts: webservers
tasks:
- name: installed nfs server
yum:
name: nfs-utils
- name: configure nfs server
template:
src: ./exports.j2
dest: /etc/exports
notify: restart nfs server
- name: create share directory
file:
path: "{{share_dir}}"
state: directory
owner: www
group: www
mode: 755
- name: started nfs server
systemd:
name: nfs
state: started
enabled: yes
handlers:
- name: restart nfs server
systemd:
name: nfs
state: restarted
- hosts: db
tasks:
- name: client mount nfs server
mount:
src: 172.16.1.7:{{share_dir}}
path: /ansible_mont
fstype: nfs
state: mounted

[root@db01 ~]#
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/centos-root 17G 2.3G 15G 14% /
devtmpfs 475M 0 475M 0% /dev
tmpfs 487M 0 487M 0% /dev/shm
tmpfs 487M 7.7M 479M 2% /run
tmpfs 487M 0 487M 0% /sys/fs/cgroup
/dev/sda1 1014M 133M 882M 14% /boot
tmpfs 98M 0 98M 0% /run/user/0
172.16.1.7:/data4 17G 2.8G 15G 17% /ansible_mont
```

2.8register变量注册，将执行的结果存储至变量中，后期可以通过结果进行判断的操作。

```HTML
[root@manager ansible_lianxi-5.18]# cat var9.yml
- hosts: webservers
tasks:
- name: Get Network Status
shell: netstat -lntp
register: System_Net
#将shell命令的执行输出结果，存储至System_Net变量中
- name: Print Variables
debug:
msg: "{{ System_Net.stdout_lines }}"
```

2.9 facts变量

Ansible facts是在被管理主机上通过ansible自动采集发现的变量。facts包含每台特定的主机信息。比如:被控端主机的主机名、IP地址、系统版本、CPU数量、内存状态、磁盘状态等等。
facts使用场景
1.通过facts检查CPU，来生成对应的nginx配置文件
2.通过facts检查主机名信息,来生成不同的Zabbix配置文件
3.通过fact检索的内存情况来自定义mysql的配置文件

1.facts基本用法，比如获取被控端的主机名与IP地址

```HTML
[root@manager ansible_lianxi-5.18]# cat var10.yml
- hosts: webservers
tasks:
- name: Output variables ansible facts
debug:
msg: >
this default IPv4 address "{{ ansible_fqdn}}" is "{{ ansible_default_ipv4.address}}"
```

2.10 实战一、根据IP地址生成不同的Redis配置

```HTML
[root@manager ansible_lianxi-5.18]# cat redis.yml
- hosts: webservers
tasks:

- name: Installed Redis Server
yum:
name: redis
state: present

- name: Configure Redis Server
template:
src: ./redis.conf.j2
dest: /etc/redis.conf
notify: Restart Redis Server

- name: Started Redis Server
systemd:
name: redis
state: started
enabled: yes

handlers:
- name: Restart Redis Server
systemd:
name: redis
state: restarted
[root@manager ansible_lianxi-5.18]# cat redis.conf.j2
bind 127.0.0.1 {{ ansible_eth1.ipv4.address }}

[root@manager ansible_lianxi-5.18]# ansible webservers -m shell -a "netstat -lntp|grep redis"

```

实战二、根据CPU核心生成不同的Nginx配置

```HTML
[root@manager ansible_lianxi-5.18]# cat ngix.yml
- hosts: webservers
tasks:
- name: Configure Nginx.conf
template:
src: ./nginx.conf.j2
dest: /tmp/nginx.conf
[root@manager ansible_lianxi-5.18]# cat nginx.conf.j2
worker {{ ansible_processor_vcpus * 2 }};
[root@manager ansible_lianxi-5.18]# ansible webservers -m shell -a "cat /tmp/nginx.conf"
172.16.1.8 | CHANGED | rc=0 >>
worker 2;
172.16.1.7 | CHANGED | rc=0 >>
worker 2;

```

实战三、根据主机内存生成不同的Memcached配置 ( 使用物理内存的一半 )

```HTML
[root@manager ansible_lianxi-5.18]# cat memcached.yml
- hosts: webservers
tasks:
- name: Installed Memcached Server
yum:
name: memcached
state: present

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

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

handlers:
- name: Restart Memcached Server
systemd:
name: memcached
state: restarted
[root@manager ansible_lianxi-5.18]# cat memcached.j2
PORT="11211"
USER="memcached"
MAXCONN="1024"
CACHESIZE="{{ ansible_memtotal_mb //2 }}"
OPTIONS=""
[root@manager ansible_lianxi-5.18]# ansible webservers -m shell -a "cat /etc/sysconfig/memcached"
172.16.1.8 | CHANGED | rc=0 >>
PORT="11211"
USER="memcached"
MAXCONN="1024"
CACHESIZE="486"
OPTIONS=""
172.16.1.7 | CHANGED | rc=0 >>
PORT="11211"
USER="memcached"
MAXCONN="1024"
CACHESIZE="486"
OPTIONS=""
```

实战四、根据主机名称生成不同的zabbix配置

```HTML
[root@manager ansible_lianxi-5.18]#wget https://mirror.tuna.tsinghua.edu.cn/zabbix/zabbix/4.0/rhel/7/x86_64/zabbix-agent-4.0.0-2.el7.x86_64.rpm
[root@manager ansible_lianxi-5.18]# yum install zabbix-agent-4.0.0-2.el7.x86_64.rpm -y
[root@manager ansible_lianxi-5.18]# cp /etc/zabbix/zabbix_agentd.conf ansible_lianxi-5.18/zabbix_agentd.conf.j2
Hostname={{ansible_hostname}}
[root@manager ansible_lianxi-5.18]# cat zabbix_agent.yml
- hosts: all
tasks:
- name: Installed ZabbixAgent
yum:
name: https://mirror.tuna.tsinghua.edu.cn/zabbix/zabbix/4.0/rhel/7/x86_64/zabbix-agent-4.0.0-2.el7.x86_64.rpm
state: present

- name: Configure ZabbixAgent
template:
src: ./zabbix_agentd.conf.j2
dest: /etc/zabbix/zabbix_agentd.conf
notify: Restart ZabbixAgent

- name: Started ZabbixAgent
systemd:
name: zabbix-agent
state: started
enabled: yes

handlers:
- name: Restart ZabbixAgent
systemd:
name: zabbix-agent
state: restarted

```

facts优化：
facts变量开启会影响playbook运行的效率？ 但是关闭又会造成无法提取被控端的状态。 最佳的方案使用缓存来解决。

```HTML
[root@manager ansible_lianxi-5.18]# cat ansible.cfg
[defaults]
inventory = ./hosts

gathering = smart
fact_caching_timeout = 86400
fact_caching = redis
fact_caching_connection = 172.16.1.7:6379
[root@manager ansible_lianxi-5.18]#yum install python-pip
[root@manager ansible_lianxi-5.18]#pip install redis
[root@web01 ~]# redis-cli
127.0.0.1:6379> keys *
1) "ansible_cache_keys"
2) "ansible_facts172.16.1.5"
3) "ansible_facts172.16.1.51"
4) "ansible_facts172.16.1.8"
5) "ansible_facts172.16.1.7"

```