ansible-playbook之条件判断
ansible条件判断
在工作中，我们在执行playbook时，需要对某些条件进行判断，只有当满足条件才执行相应的tasks;
1.when条件判断：只条满足when的条件时才执行对应的tasks
注：when关键字后面跟着的是python的表达式,在表达式中你能够使用任何的变量或者facts
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#注：当需要用远程主机的一些信息时，gather_facts必须要开启，默认是开启状态[[email protected] playbook]# cat when.yml
---- hosts: webservers remote_user: root
#gather_facts: False
tasks:
- name: Host 192.168.1.101 run this task
debug: 'msg=" {{ ansible_default_ipv4.address }}"'
when: ansible_default_ipv4.address == "192.168.2.101"
- name: memtotal < 500M and processor_cores == 2 run this task
debug: 'msg="{{ ansible_fqdn }}"'
when: ansible_memtotal_mb < 500 and ansible_processor_cores == 2
- name: all host run this task
shell: hostname
register: info
- name: Hostname is lamp1 Machie run this task
debug: 'msg="{{ ansible_fqdn }}"'
when: info['stdout'] == "lamp1"
- name: Hostname is startswith l run this task
debug: 'msg="{{ ansible_fqdn }}"'
when: info['stdout'].startswith('l')
[[email protected] playbook]# ansible-playbook when.yml
PLAY [webservers] **************************************************************************************************************************************TASK [Gathering Facts] *********************************************************************************************************************************ok: [192.168.2.101]ok: [192.168.2.111]TASK [Host 192.168.1.101 run this task] ****************************************************************************************************************ok: [192.168.2.101] => { "msg": " 192.168.2.101"
}skipping: [192.168.2.111]TASK [memtotal < 500M and processor_cores == 2 run this task] ******************************************************************************************skipping: [192.168.2.101]skipping: [192.168.2.111]TASK [all host run this task] **************************************************************************************************************************changed: [192.168.2.101]changed: [192.168.2.111]TASK [Hostname is lamp1 Machie run this task] **********************************************************************************************************ok: [192.168.2.101] => { "msg": "lamp1"
}skipping: [192.168.2.111]TASK [Hostname is startswith l run this task] **********************************************************************************************************ok: [192.168.2.101] => { "msg": "lamp1"
}ok: [192.168.2.111] => { "msg": "lamp2"
}PLAY RECAP *********************************************************************************************************************************************192.168.2.101 : ok=5 changed=1 unreachable=0 failed=0 192.168.2.111 : ok=3 changed=1 unreachable=0 failed=0 |
2.changed_when：先执行task,并对task返回的值进行判断，当满足changed_when指定的条件时说明是执行成功的
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#注：默认情况下执行了命令的主机状态都为changed，本例对输出进行判断，包含是某个指定字符才能为changed; [[email protected] playbook]# cat when_1.yml
---- hosts: webservers remote_user: root
#gather_facts: False
tasks:
- name: all host run this task
shell: hostname
register: info
changed_when: '"lamp1" in info.stdout'
[[email protected] playbook]# ansible-playbook when_1.yml
PLAY [webservers] **************************************************************************************************************************************TASK [Gathering Facts] *********************************************************************************************************************************ok: [192.168.2.101]ok: [192.168.2.111]TASK [all host run this task] **************************************************************************************************************************ok: [192.168.2.111]changed: [192.168.2.101]PLAY RECAP *********************************************************************************************************************************************192.168.2.101 : ok=2 changed=1 unreachable=0 failed=0 192.168.2.111 : ok=2 changed=0 unreachable=0 failed=0 |
3.failed_when:当执行失败后，会将信息存在register的stderr中，通过判断指定的字符是否在stderr中来确定是否真的失败；
暂时没有合适的例子，等有了再补~
本文转自激情燃烧的岁月博客51CTO博客，原文链接http://blog.51cto.com/liuzhengwei521/1962382如需转载请自行联系原作者
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