ansible的条件判断、迭代执行、tags-原创手记-慕课网

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

[root@node1 ansible]# 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

[root@node1 ansible]# cat http.yml

- hosts: testservers

remote_user: root

tasks:

- name: uninstall httpd service

yum: name=httpd state=absent

when: ansible_nodename == "v2.lansgg.com"

[root@node1 ansible]# ansible-playbook http.yml

PLAY [testservers] ************************************************************

GATHERING FACTS ***************************************************************

ok: [192.168.100.131]

ok: [192.168.100.132]

TASK: [uninstall httpd service] ***********************************************

skipping: [192.168.100.132]

changed: [192.168.100.131]

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

[root@node1 ansible]# 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

[root@node1 ansible]#

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，

[root@node1 ansible]# 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

[root@node1 ansible]# 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[0] == '192.168.100.132')

[root@node1 ansible]# ansible-playbook http.yml

PLAY [testservers] ************************************************************

GATHERING FACTS ***************************************************************

ok: [192.168.100.131]

ok: [192.168.100.132]

TASK: [uninstall httpd service] ***********************************************

changed: [192.168.100.131]

changed: [192.168.100.132]

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

[root@node1 ansible]# 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

[root@node1 ansible]#

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

[root@node1 ansible]# 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

[root@node1 ansible]# cat re.yml

- hosts: testservers

remote_user: root

tasks:

- name: ls /nono

shell: /bin/ls /nono

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

[root@node1 ansible]# ansible-playbook re.yml

PLAY [testservers] ************************************************************

GATHERING FACTS ***************************************************************

ok: [192.168.100.131]

ok: [192.168.100.132]

TASK: [ls /nono] **************************************************************

changed: [192.168.100.131]

failed: [192.168.100.132] => {"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: [test result] ***********************************************************

skipping: [192.168.100.132]

ok: [192.168.100.131]

TASK: [test no result] ********************************************************

skipping: [192.168.100.131]

ok: [192.168.100.132]

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

[root@node1 ansible]# ansible testservers -m shell -a 'ls -l /tmp/test'

192.168.100.131 | success | rc=0 >>

-rw-r--r-- 1 root root 2 Mar 2 12:55 /tmp/test

192.168.100.132 | success | rc=0 >>

-rw-r--r-- 1 root root 5 Mar 2 12:55 /tmp/test

[root@node1 ansible]# ansible testservers -m shell -a 'cat /tmp/test'

192.168.100.131 | success | rc=0 >>

192.168.100.132 | success | rc=0 >>

no ok

[root@node1 ansible]#

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

[root@node1 ansible]# 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")

[root@node1 ansible]#

上面的语句等同于：

- 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：

- 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：

[root@node1 ansible]# ansible-playbook item.yml

PLAY [testservers] ************************************************************

GATHERING FACTS ***************************************************************

ok: [192.168.100.131]

ok: [192.168.100.132]

TASK: [yum install lamp] ******************************************************

skipping: [192.168.100.132]

changed: [192.168.100.131] => (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、

[root@node1 ansible]# 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：

[root@node1 ansible]# ansible-playbook tag.yml --tags="A1,A3"

PLAY [testservers] ************************************************************

GATHERING FACTS ***************************************************************

ok: [192.168.100.131]

ok: [192.168.100.132]

TASK: [echo A1] ***************************************************************

changed: [192.168.100.131]

changed: [192.168.100.132]

TASK: [echo A3] ***************************************************************

changed: [192.168.100.131]

changed: [192.168.100.132]

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：

[root@node1 ansible]# ansible-playbook tag.yml --skip-tags="A2"

PLAY [testservers] ************************************************************

GATHERING FACTS ***************************************************************

ok: [192.168.100.131]

ok: [192.168.100.132]

TASK: [echo A1] ***************************************************************

changed: [192.168.100.132]

changed: [192.168.100.131]

TASK: [echo A3] ***************************************************************

changed: [192.168.100.131]

changed: [192.168.100.132]

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，

[root@node1 ansible]# 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

[root@node1 ansible]#

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：

[root@node1 ansible]# ansible-playbook http.yml --tags=modify

PLAY [testservers] ************************************************************

GATHERING FACTS ***************************************************************

ok: [192.168.100.131]

ok: [192.168.100.132]

TASK: [copy config file] ******************************************************

changed: [192.168.100.131]

changed: [192.168.100.132]

NOTIFIED: [restart httpd service] *********************************************

changed: [192.168.100.131]

changed: [192.168.100.132]

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

特殊 tags

系统中内置的特殊tags：

always、tagged、untagged、all 是四个系统内置的tag，有自己的特殊意义

always: 指定这个tag 后，task任务将永远被执行，而不用去考虑是否使用了--skip-tags标记

tagged: 当 --tags 指定为它时，则只要有tags标记的task都将被执行,--skip-tags效果相反

untagged: 当 --tags 指定为它时，则所有没有tag标记的task 将被执行,--skip-tags效果相反

all: 这个标记无需指定，ansible-playbook 默认执行的时候就是这个标记.所有task都被执行

whentagsitemAnsible