今天碰到一個需求，當使用ansible-playbook在執行一個腳本后，根據腳本返回的內容判斷是否繼續往下執行還是中斷執行，查詢官網發現使用register寄存器可以實現記錄腳本輸出，使用when+fail模塊來判斷是否往下繼續執行或者中斷，以下是一個簡單例子：

ansible服務在172.16.133.128上，先執行一個腳本，腳本返回success時在172.16.133.129上創建一個目錄/tmp/test，如果返回failed則中斷執行

先在172.16.133.129上配置一個簡單腳本/tmp/test.sh

#!/bin/bash
echo "failed"

配置yml文件test.yml，先配置執行腳本部分

---

• hosts: 172.16.133.129
  remote_user: root
  tasks:
  • command: /tmp/test.sh
    register: result
    這里使用了register寄存器，具體寄存了什么內容，可以使用-v參數來查看輸出

使用ansible-playbook運行

[root@localhost ansible]# ansible-playbook -v test.yml
PLAY [172.16.133.129] *
GATHERING FACTS ***
ok: [172.16.133.129]
TASK: [command /tmp/test.sh] **
changed: [172.16.133.129] => {"changed": true, "cmd": ["/tmp/test.sh"], "delta": "0:00:00.002602", "end": "2016-04-11 17:00:57.227517", "rc": 0, "start": "2016-04-11 17:00:57.224915", "stderr": "", "stdout": "failed", "warnings": []}
PLAY RECAP ****
172.16.133.129 : ok=2 changed=1 unreachable=0 failed=0
register保存的信息就時“=>”后面的字典信息，信息保存在result變量中

可以看到"stdout"就是腳本的標準輸出信息，這時可以使用"when"來判斷是否執行或者跳過

修改test.yml

---

• hosts: 172.16.133.129
  remote_user: root
  tasks:

  • command: /tmp/test.sh
    register: result

  • file: path=/tmp/test state=directory
    when: result.stdout == ‘failed‘
    當腳本輸出為‘failed‘時就會執行創建目錄操作，輸出不為‘failed‘，則跳過執行

執行yml后輸出如下：

[root@localhost ansible]# ansible-playbook -v test.yml

PLAY [172.16.133.129] *****

GATHERING FACTS ***
ok: [172.16.133.129]

TASK: [command /tmp/test.sh] **
changed: [172.16.133.129] => {"changed": true, "cmd": ["/tmp/test.sh"], "delta": "0:00:00.002618", "end": "2016-04-11 17:11:07.957097", "rc": 0, "start": "2016-04-11 17:11:07.954479", "stderr": "", "stdout": "failed", "warnings": []}

TASK: [file path=/tmp/test state=directory] ***
changed: [172.16.133.129] => {"changed": true, "gid": 0, "group": "root", "mode": "0755", "owner": "root", "path": "/tmp/test", "size": 4096, "state": "directory", "uid": 0}

PLAY RECAP ****
172.16.133.129 : ok=3 changed=2 unreachable=0 failed=0

修改test.sh，輸出‘success‘，然后執行test.yml

[root@localhost ansible]# ansible-playbook -v test.yml

PLAY [172.16.133.129] *****

GATHERING FACTS ***
ok: [172.16.133.129]

TASK: [command /tmp/test.sh] **
changed: [172.16.133.129] => {"changed": true, "cmd": ["/tmp/test.sh"], "delta": "0:00:00.002611", "end": "2016-04-11 17:14:08.456293", "rc": 0, "start": "2016-04-11 17:14:08.453682", "stderr": "", "stdout": "success", "warnings": []}

TASK: [file path=/tmp/test state=directory] ***
skipping: [172.16.133.129]

PLAY RECAP ****
172.16.133.129 : ok=2 changed=1 unreachable=0 failed=0
可以看到當stdout為success時，創建目錄的操作直接跳過了

現在回到最終要達到的目的，當腳本輸出為‘failed‘時，我們要中斷ansible-playbook執行，而不是跳過，這時需要配合fail模塊來實現，并且可以拋出自定義信息

修改test.sh文件,輸出‘failed‘

修改test.yml

---

• hosts: 172.16.133.129
  remote_user: root
  tasks:

  • command: /tmp/test.sh
    register: result

  • name: if stdout ‘failed‘ ,Interrupt execution
    fail: msg="check failed"
    when: result.stdout == ‘failed‘

  • file: path=/tmp/test state=directory
    如果腳本執行返回‘failed‘，中斷執行，并拋出信息"check failed"

[root@localhost ansible]# ansible-playbook -v test.yml

PLAY [172.16.133.129] *****

GATHERING FACTS ***
ok: [172.16.133.129]

TASK: [command /tmp/test.sh] **
changed: [172.16.133.129] => {"changed": true, "cmd": ["/tmp/test.sh"], "delta": "0:00:00.002632", "end": "2016-04-11 17:27:47.248996", "rc": 0, "start": "2016-04-11 17:27:47.246364", "stderr": "", "stdout": "failed", "warnings": []}

TASK: [check ,Interrupt execution] ****
failed: [172.16.133.129] => {"failed": true}
msg: check failed

FATAL: all hosts have already failed -- aborting

PLAY RECAP ****
to retry, use: --limit @/root/test.retry

172.16.133.129 : ok=2 changed=1 unreachable=0 failed=1
playbook運行到第二個task時就會報錯并拋出msg

ansible官網文檔：http://docs.ansible.com/ansible/playbooks_conditionals.html#register-variables

注：寄存器中的數據都可以拿來使用，如"rc","stderr"等，當然也有很多種方法，文中的‘failed‘是嚴格匹配，也可以使用模糊查找，如result.stdout.find(‘failed‘) != -1也可以達到相同的效果

本文出自 “漂泊的魚” 博客，請務必保留此出處http://faded.blog.51cto.com/6375932/1762688

轉載于:https://blog.51cto.com/lookingdream/2054763

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