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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[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]
#
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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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[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]
#
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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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[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
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
[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 >>
ok
192.168.100.132 | success | rc=0 >>
no ok
[root@node1 ansible]
#
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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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[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]
#
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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"
)
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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'
}
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开始执行：
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[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
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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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[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
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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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[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
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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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[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
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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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[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]
#
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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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[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
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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
本文转自 西索oO 51CTO博客，原文链接:http://blog.51cto.com/lansgg/1746825
