ansible playbook 中的 handlers

  执行 task 之后，服务器发生变化之后要执行的一些操作，比如修改了配置文件之后，需要重启一下服务，那么必须确保配置文件真的被修改了，才能重启。

  例：

[root@server ansible]# vim handlers.yml

---

- hosts: client.test.com

  name: handlers test

  user: root

  tasks:

   - name: copy file

     copy: src=/etc/passwd dest=/tmp/aaa.txt

     notify: test handlers

  handlers:

   - name: test handlers

     shell: echo "11111" >> /tmp/aaa.txt


[root@server ansible]# ansible-playbook handlers.yml



PLAY [handlers test] ***********************************************************



TASK [setup] *******************************************************************

ok: [client.test.com]



TASK [copy file] ***************************************************************

changed: [client.test.com]



RUNNING HANDLER [test handlers] ************************************************

changed: [client.test.com]



PLAY RECAP *********************************************************************

client.test.com            : ok=3    changed=2    unreachable=0    failed=0

  查看一下 aaa.txt

[root@server ansible]# ansible client.test.com -m shell -a "tail -5 /tmp/aaa.txt"

client.test.com | SUCCESS | rc=0 >>

apache:x:48:48:Apache:/var/www:/sbin/nologin

nrpe:x:497:498:NRPE user for the NRPE service:/var/run/nrpe:/sbin/nologin

puppet:x:52:52:Puppet:/var/lib/puppet:/sbin/nologin

test:x:500:500::/home/test:/bin/bash

11111

  可以看到 passwd 文件复制过去了，11111 也被追加，此操作是在 passwd 和 aaa.txt 文件内容不一致的前提下完成的，如果两者内容一样，copy 不会执行，handlers 就不会被调用。试验一下：

  先把 passwd 复制到 aaa.txt

[root@server ansible]# rsync -av /etc/passwd client.test.com:/tmp/aaa.txt

sending incremental file list

passwd



sent 634 bytes  received 43 bytes  1354.00 bytes/sec

total size is 1256  speedup is 1.86

  再去执行：

[root@server ansible]# ansible-playbook handlers.yml

PLAY [handlers test] ***********************************************************



TASK [setup] *******************************************************************

ok: [client.test.com]



TASK [copy file] ***************************************************************

ok: [client.test.com]



PLAY RECAP *********************************************************************

client.test.com            : ok=2    changed=0    unreachable=0    failed=0

  查看一下，没有 11111 了

[root@server ansible]# ansible client.test.com -m shell -a "tail -5 /tmp/aaa.txt"

client.test.com | SUCCESS | rc=0 >>

rpc:x:32:32:Rpcbind Daemon:/var/cache/rpcbind:/sbin/nologin

apache:x:48:48:Apache:/var/www:/sbin/nologin

nrpe:x:497:498:NRPE user for the NRPE service:/var/run/nrpe:/sbin/nologin

puppet:x:52:52:Puppet:/var/lib/puppet:/sbin/nologin

test:x:500:500::/home/test:/bin/bash