ansible的条件判断、迭代执行、tags
在ansible中支持条件判断，这使我们操作更加灵活使用when进行条件测试
示例1：
将 testservers 组中的其中一台主机上的 httpd 服务卸载掉，另外主机不卸载
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# ansible testservers -m shell -a 'rpm -q httpd'
192.168.100.131 | success | rc=0 >>
httpd-2.2.15-29.el6.centos.x86_64
192.168.100.132 | success | rc=0 >>
httpd-2.2.15-47.el6.centos.3.x86_64
# cat http.yml
- hosts: testservers
remote_user: root
tasks:
- name: uninstall httpd service
yum: name=httpd state=absent
when: ansible_nodename == "v2.lansgg.com"
# ansible-playbook http.yml
PLAY ************************************************************
GATHERING FACTS ***************************************************************
ok:
ok:
TASK: ***********************************************
skipping:
changed:
PLAY RECAP ********************************************************************
192.168.100.131 : ok=2 changed=1 unreachable=0 failed=0
192.168.100.132 : ok=1 changed=0 unreachable=0 failed=0
# ansible testservers -m shell -a 'rpm -q httpd'
192.168.100.132 | success | rc=0 >>
httpd-2.2.15-47.el6.centos.3.x86_64
192.168.100.131 | FAILED | rc=1 >>
package httpd is not installed
#
示例2：
也可以使用 or 进行 或 判断，这里将组内的两台主机的 httpd 服务都卸载，
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# ansible testservers -m shell -a 'rpm -q httpd'
192.168.100.132 | success | rc=0 >>
httpd-2.2.15-47.el6.centos.3.x86_64
192.168.100.131 | success | rc=0 >>
httpd-2.2.15-29.el6.centos.x86_64
# cat http.yml
- hosts: testservers
remote_user: root
tasks:
- name: uninstall httpd service
yum: name=httpd state=absent
when: (ansible_nodename == "v2.lansgg.com") or ( ansible_all_ipv4_addresses == '192.168.100.132')
# ansible-playbook http.yml
PLAY ************************************************************
GATHERING FACTS ***************************************************************
ok:
ok:
TASK: ***********************************************
changed:
changed:
PLAY RECAP ********************************************************************
192.168.100.131 : ok=2 changed=1 unreachable=0 failed=0
192.168.100.132 : ok=2 changed=1 unreachable=0 failed=0
# ansible testservers -m shell -a 'rpm -q httpd'
192.168.100.131 | FAILED | rc=1 >>
package httpd is not installed
192.168.100.132 | FAILED | rc=1 >>
package httpd is not installed
#
保存结果几乎所有的模块都是会outputs一些东西,甚至debug模块也会.大多数我们会使用的结果变量是changed.这个changed变量决定了是否要直接handlers和输出的颜色是什么.然而,结果变量还有其他的用途,譬如我需要保存我的结果变量,然后在我们的playbook的其他地方使用.
示例：
分别在一台主机上创建一个目录，另外主机不存在此目录，根据此目录的存在情况，做出不同操作
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# ansible testservers -m shell -a 'ls -l /nono'
192.168.100.131 | success | rc=0 >>
total 0
192.168.100.132 | FAILED | rc=2 >>
ls: cannot access /nono: No such file or directory
# cat re.yml
- hosts: testservers
remote_user: root
tasks:
- name: ls /nono
shell: /bin/ls /nono
register: result
ignore_errors: True
- name: test result
copy: content="ok" dest=/tmp/test
when: result.rc == 0
- name: test no result
copy: content="no ok" dest=/tmp/test
when: result.rc != 0
# ansible-playbook re.yml
PLAY ************************************************************
GATHERING FACTS ***************************************************************
ok:
ok:
TASK: **************************************************************
changed:
failed: => {"changed": true, "cmd": "/bin/ls /nono", "delta": "0:00:00.004437", "end": "2016-03-02 12:56:55.409736", "rc": 2, "start": "2016-03-02 12:56:55.405299", "warnings": []}
stderr: /bin/ls: cannot access /nono: No such file or directory
...ignoring
TASK: ***********************************************************
skipping:
ok:
TASK: ********************************************************
skipping:
ok:
PLAY RECAP ********************************************************************
192.168.100.131 : ok=3 changed=1 unreachable=0 failed=0
192.168.100.132 : ok=3 changed=1 unreachable=0 failed=0
# ansible testservers -m shell -a 'ls -l /tmp/test'
192.168.100.131 | success | rc=0 >>
-rw-r--r-- 1 root root 2 Mar2 12:55 /tmp/test
192.168.100.132 | success | rc=0 >>
-rw-r--r-- 1 root root 5 Mar2 12:55 /tmp/test
# ansible testservers -m shell -a 'cat /tmp/test'
192.168.100.131 | success | rc=0 >>
ok
192.168.100.132 | success | rc=0 >>
no ok
#
ansible 中的循环操作：
当有需要重复性执行的任务时，可以使用迭代机制，格式为：将需要迭代的内容定义为Item变量引用，并通过with_items 语句来指明迭代的元素列表即可
示例1、
在 testservers 组中一台主机上安装lamp
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# cat item.yml
- hosts: testservers
remote_user: root
tasks:
- name: yum install lamp
yum: name={{item}} state=present
with_items:
- httpd
- mysql-server
- php
when: (ansible_nodename == "v2.lansgg.com")
#
上面的语句等同于：
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- hosts: testservers
remote_user: root
tasks:
- name: install httpd
yum: name=httpd state=present
when: (ansible_nodename == "v2.lansgg.com")
- name: install mysql-server
yum: name=mysql-server state=present
when: (ansible_nodename == "v2.lansgg.com")
- name: install php
yum: name=php state=present
when: (ansible_nodename == "v2.lansgg.com")
上面的语句 hash 方式编写也可以，等同于如下：
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- hosts: testservers
remote_user: root
tasks:
- name: install httpd
yum: name={{item.name}} state={{item.state}}
when: (ansible_nodename == "v2.lansgg.com")
with_items:
- {name: 'httpd', state: 'present'}
- {name: 'mysql-server', state: 'present'}
- {name: 'php', state: 'present'}
开始执行：
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# ansible-playbook item.yml
PLAY ************************************************************
GATHERING FACTS ***************************************************************
ok:
ok:
TASK: ******************************************************
skipping:
changed: => (item=httpd,mysql-server,php)
PLAY RECAP ********************************************************************
192.168.100.131 : ok=2 changed=1 unreachable=0 failed=0
192.168.100.132 : ok=1 changed=0 unreachable=0 failed=0
ansible 的 tags 功能
ansible的playbool中有一个关键字，叫做tags。tags是什么？就是打标签。tags可以和一个play（就是很多个task）或者一个task进行捆绑。然后，ansible-playbook提供了“--skip-tags”和“--tags” 来指明是跳过特定的tags还是执行特定的tags。
示例 1、
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# cat tag.yml
- hosts: testservers
remote_user: root
tasks:
- name: echo A1
command: echo A1
tags:
- A1
- name: echo A2
command: echo A2
tags:
- A2
- name: echo A3
command: echo A3
tags:
- A3
当执行ansible-playbook tag.yml --tags="A1,A3,则只会执行A1和A3的echo命令。
如下：
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# ansible-playbook tag.yml --tags="A1,A3"
PLAY ************************************************************
GATHERING FACTS ***************************************************************
ok:
ok:
TASK: ***************************************************************
changed:
changed:
TASK: ***************************************************************
changed:
changed:
PLAY RECAP ********************************************************************
192.168.100.131 : ok=3 changed=2 unreachable=0 failed=0
192.168.100.132 : ok=3 changed=2 unreachable=0 failed=0
当执行ansible-playbook tag.yml --skip-tags="A2" ,同样只会执行 A1和A3的echo命令。
如下：
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# ansible-playbook tag.yml --skip-tags="A2"
PLAY ************************************************************
GATHERING FACTS ***************************************************************
ok:
ok:
TASK: ***************************************************************
changed:
changed:
TASK: ***************************************************************
changed:
changed:
PLAY RECAP ********************************************************************
192.168.100.131 : ok=3 changed=2 unreachable=0 failed=0
192.168.100.132 : ok=3 changed=2 unreachable=0 failed=0
示例 2 、
我们安装 httpd 服务的流程为 安装服务、copy文件、启动服务、如果配置有变化就重启服务，
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# cat http.yml
- hosts: testservers
remote_user: root
tasks:
- name: install httpd package
yum: name=httpd state=present
- name: start httpd service
service: name=httpd enabled=true state=started
- name: copy config file
copy: src=httpd.conf dest=/etc/httpd/conf/httpd.conf
notify:
restart httpd service
tags:
- modify
handlers:
- name: restart httpd service
service: name=httpd state=restarted
#
当我们的配置文件有修改的时候，可以指定tags，这样就会只执行copy config file 任务，前面就不会再执行
结果如下：
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# ansible-playbook http.yml --tags=modify
PLAY ************************************************************
GATHERING FACTS ***************************************************************
ok:
ok:
TASK: ******************************************************
changed:
changed:
NOTIFIED: *********************************************
changed:
changed:
PLAY RECAP ********************************************************************
192.168.100.131 : ok=3 changed=2 unreachable=0 failed=0
192.168.100.132 : ok=3 changed=2 unreachable=0 failed=0
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