基于条件测试实现角色调用
基于条件测试实现角色调用
实例：指定 memcached 的运行内存大小为总大小的 1/4，并只有centos 7版本系统才执行操作
```
[root@localhost ~]# mkdir -pv /etc/ansible/roles/memcached/tasks
[root@localhost ~]# vim /etc/ansible/roles/memcached/tasks/main.yml
-------------------------------------------------------------------------------------------------------
- name: install memcached package
yum: name=memcached state=present
- name: install conf file
template: src=memcached.j2 dest=/etc/sysconfig/memcached
notify: restarted memcached
tags: restmemcached
- name: start memcached
service: name=memcached state=started enabled=true
[root@localhost ~]# vim /etc/sysconfig/memcached
-------------------------------------------------------------------------------------------------------
PORT="11211"
USER="memcached"
MAXCONN="1024"
CACHESIZE="64"
OPTIONS=""
[root@localhost ~]# cd /etc/ansible/roles/memcached/
[root@localhost memcached]# mkdir templates
[root@localhost memcached]# cp /etc/sysconfig/memcached ./templates/
[root@localhost memcached]# vim templates/memcached
-------------------------------------------------------------------------------------------------------
PORT="11211"
USER="memcached"
MAXCONN="1024"
CACHESIZE="{{ ansible_memtotal_mb//4 }}"
OPTIONS=""
[root@localhost memcached]# cd templates/
[root@localhost templates]# mv memcached memcached.j2
[root@localhost templates]# cd ..
[root@localhost memcached]# mkdir
[root@localhost templates]# vim memcached/handlers/main.yml
-------------------------------------------------------------------------------------------------------
- name: restarted memcached
service: name=memcached state=restarted
[root@localhost templates]# cd
[root@localhost ~]# cd ansible/
[root@localhost ansible]# vim memcached.yml
-------------------------------------------------------------------------------------------------------
- hosts: dbservers
remote_user: root
roles:
- { role: memcached,username: nginx,when: ansible_distribution_major_version == '7' }
[root@localhost ansible]# ansible-playbook --check memcached.yml
PLAY [dbservers] **************************************************************
GATHERING FACTS ***************************************************************
ok: [172.18.77.84]
TASK: [memcached | install memcached package] *********************************
ok: [172.18.77.84]
TASK: [memcached | install conf file] *****************************************
changed: [172.18.77.84]
TASK: [memcached | start memcached] *******************************************
ok: [172.18.77.84]
NOTIFIED: [memcached | restarted memcached] ***********************************
changed: [172.18.77.84]
PLAY RECAP ********************************************************************
172.18.77.84 : ok=5 changed=2 unreachable=0 failed=0
[root@localhost ansible]# ansible-playbook memcached.yml
[root@localhost ansible]# cat /etc/sysconfig/memcached
PORT="11211"
USER="memcached"
MAXCONN="1024"
CACHESIZE="244"
OPTIONS=""
```