ansible 条件判断+循环

条件判断
When 语句
在when 后面使用Jinja2 表达式，结果为True则执行任务。

[code]tasks:
- name: "shut down Debian flavored systems"
command: /sbin/shutdown -t now
when: ansible_os_family == "Debian"

若操作系统是Debian 时就执行关机操作
可以对条件进行分组在比较。

tasks:
- name: "shut down CentOS 6 and Debian 7 systems"
command: /sbin/shutdown -t now
when: (ansible_distribution == "CentOS" and ansible_distribution_major_version == "6") or
(ansible_distribution == "Debian" and ansible_distribution_major_version == "7")

可以使用列表形式来表示条件为and的关系

tasks:
- name: "shut down CentOS 6 systems"
command: /sbin/shutdown -t now
when:
- ansible_distribution == "CentOS"
- ansible_distribution_major_version == "6"

使用jinja2过滤器

tasks:
- command: /bin/false
register: result
ignore_errors: True

- command: /bin/something
when: result|failed

- command: /bin/something_else
when: result|succeeded

- command: /bin/still/something_else
when: result|skipped

忽略一个语句的错误，然后决定基于成功或失败有条件地做一些事情。
字符串转换为数字型再去比较

tasks:
- shell: echo "only on Red Hat 6, derivatives, and later"
when: ansible_os_family == "RedHat" and ansible_lsb.major_release|int >= 6

使用变量进行判断

vars:
epic: true
tasks:
- shell: echo "This certainly is epic!"
when: epic
tasks:
- shell: echo "This certainly isn't epic!"
when: not epic

判断变量是否定义

tasks:
- shell: echo "I've got '{{ foo }}' and am not afraid to use it!"
when: foo is defined

- fail: msg="Bailing out. this play requires 'bar'"
when: bar is undefined

与循环一起使用

tasks:
- command: echo {{ item }}
with_items: [ 0, 2, 4, 6, 8, 10 ]
when: item > 5

依次遍历列表，当列表里得数字大于5时执行任务

- command: echo {{ item }}
with_items: "{{ mylist|default([]) }}"
when: item > 5
- command: echo {{ item.key }}
with_dict: "{{ mydict|default({}) }}"
when: item.value > 5

当变量不存在时，直接跳过
使用自定义的facts值做判断

tasks:
- name: gather site specific fact data
action: site_facts
- command: /usr/bin/thingy
when: my_custom_fact_just_retrieved_from_the_remote_system == '1234'

角色包含使用when

- include: tasks/sometasks.yml
when: "'reticulating splines' in output"
- hosts: webservers
roles:
- { role: debian_stock_config, when: ansible_os_family == 'Debian' }

基于变量选择文件和模板

- name: template a file
template: src={{ item }} dest=/etc/myapp/foo.conf
with_first_found:
- files:
- {{ ansible_distribution }}.conf
- default.conf
paths:
- search_location_one/somedir/
- /opt/other_location/somedir/

使用注册变量判断

- name: test play
hosts: all

tasks:

- shell: cat /etc/motd
register: motd_contents

- shell: echo "motd contains the word hi"
when: motd_contents.stdout.find('hi') != -1

failed_when

满足条件时，使任务失败

tasks:
- command: echo faild.
register: command_result
failed_when: "'faild' in command_result.stdout"
- debug: msg="echo test"

还可以写成这样

tasks:
- command: echo faild.
register: command_result
ignore_errors: True

- name: fail the echo
fail: msg="the command failed"
when: "'faild' in command_result.stdout"
- debug: msg="echo test"

changed_when

更改任务的状态。

- name: Install dependencies via Composer.
command: "/usr/local/bin/composer global require phpunit/phpunit --prefer-dist"
register: composer
changed_when: "'Nothing to install or update' not in composer.stdout"

当使用PHP Composer作为安装项目依赖项的命令时，知道什么时候是有用的Composer安装了一些东西，或什么都没有改变。

循环

标准循环
添加多个用户

- name: add several users
user: name={{ item }} state=present groups=wheel
with_items:
- testuser1
- testuser2

添加多个用户，并将用户加入不同的组内。

- name: add several users
user: name={{ item.name }} state=present groups={{ item.groups }}
with_items:
- { name: 'testuser1', groups: 'wheel' }
- { name: 'testuser2', groups: 'root' }

嵌套循环
分别给用户授予3个数据库的所有权限

- name: give users access to multiple databases
mysql_user: name={{ item[0] }} priv={{ item[1] }}.*:ALL append_privs=yes password=foo
with_nested:
- [ 'alice', 'bob' ]
- [ 'clientdb', 'employeedb', 'providerdb' ]

遍历字典
输出用户的姓名和电话

tasks:
- name: Print phone records
debug: msg="User {{ item.key }} is {{ item.value.name }} ({{ item.value.telephone }})"
with_dict: {'alice':{'name':'Alice Appleworth', 'telephone':'123-456-789'},'bob':{'name':'Bob Bananarama', 'telephone':'987-654-3210'} }

并行遍历列表

tasks:
- debug: "msg={{ item.0 }} and {{ item.1 }}"
with_together:
- [ 'a', 'b', 'c', 'd','e' ]
- [ 1, 2, 3, 4 ]

如果列表数目不匹配，用None补全
遍历列表和索引

- name: indexed loop demo
debug: "msg='at array position {{ item.0 }} there is a value {{ item.1 }}'"
with_indexed_items: [1,2,3,4]

item.0 为索引，item.1为值
遍历文件列表的内容

---
- hosts: all
tasks:
- debug: "msg={{ item }}"
with_file:
- first_example_file
- second_example_file

遍历目录文件
with_fileglob匹配单个目录中的所有文件，非递归匹配模式。

---
- hosts: all
tasks:
- file: dest=/etc/fooapp state=directory
- copy: src={{ item }} dest=/etc/fooapp/ owner=root mode=600
with_fileglob:
- /playbooks/files/fooapp/*

当在role中使用with_fileglob的相对路径时，Ansible解析相对于roles/<rolename>/files目录的路径。
遍历ini文件

lookup.ini
[section1]
value1=section1/value1
value2=section1/value2

[section2]
value1=section2/value1
value2=section2/value2

- debug: msg="{{ item }}"
with_ini: value[1-2] section=section1 file=lookup.ini re=true

获取section1 里的value1和value2的值
重试循环 until

- action: shell /usr/bin/foo
register: result
until: result.stdout.find("all systems go") != -1
retries: 5
delay: 10

"重试次数retries" 的默认值为3，"delay"为5。
查找第一个匹配文件

tasks:
- debug: "msg={{ item }}"
with_first_found:
- "/tmp/a"
- "/tmp/b"
- "/tmp/default.conf"

依次寻找列表中的文件，找到就返回。如果列表中的文件都找不到，任务会报错。
随机选择with_random_choice
随机选择列表中得一个值

- debug: msg={{ item }}
with_random_choice:
- "go through the door"
- "drink from the goblet"
- "press the red button"
- "do nothing"

循环程序的结果

tasks:
- debug: "msg={{ item }}"
with_lines: ps aux

循环子元素
定义好变量

#varfile
---
users:
- name: alice
authorized:
- /tmp/alice/onekey.pub
- /tmp/alice/twokey.pub
mysql:
password: mysql-password
hosts:
- "%"
- "127.0.0.1"
- "::1"
- "localhost"
privs:
- "*.*:SELECT"
- "DB1.*:ALL"
- name: bob
authorized:
- /tmp/bob/id_rsa.pub
mysql:
password: other-mysql-password
hosts:
- "db1"
privs:
- "*.*:SELECT"
- "DB2.*:ALL"

---
- hosts: web
vars_files: varfile
tasks:

- user: name={{ item.name }} state=present generate_ssh_key=yes
with_items: "{{ users }}"

- authorized_key: "user={{ item.0.name }} key='{{ lookup('file', item.1) }}'"
with_subelements:
- "{{ users }}"
- authorized

- name: Setup MySQL users
mysql_user: name={{ item.0.name }} password={{ item.0.mysql.password }} host={{ item.1 }} priv={{ item.0.mysql.privs | join('/') }}
with_subelements:
- "{{ users }}"
- mysql.hosts

{{ lookup('file', item.1) }} 是查看item.1文件的内容
with_subelements 遍历哈希列表，然后遍历列表中的给定（嵌套）的键。
在序列中循环with_sequence
with_sequence以递增的数字顺序生成项序列。 您可以指定开始，结束和可选步骤值。
参数应在key = value对中指定。 'format'是一个printf风格字符串。
数字值可以以十进制，十六进制（0x3f8）或八进制（0600）指定。 不支持负数。

---
- hosts: all

tasks:

# 创建组
- group: name=evens state=present
- group: name=odds state=present

# 创建格式为testuser%02x 的0-32 序列的用户
- user: name={{ item }} state=present groups=evens
with_sequence: start=0 end=32 format=testuser%02x

# 创建4-16之间得偶数命名的文件
- file: dest=/var/stuff/{{ item }} state=directory
with_sequence: start=4 end=16 stride=2

# 简单实用序列的方法：创建4 个用户组分表是组group1 group2 group3 group4
- group: name=group{{ item }} state=present
with_sequence: count=4

随机选择with_random_choice
随机选择列表中得一个值

- debug: msg={{ item }}
with_random_choice:
- "go through the door"
- "drink from the goblet"
- "press the red button"
- "do nothing"

合并列表

# 安装所有列表中的软件
- name: flattened loop demo
yum: name={{ item }} state=installed
with_flattened:
- [ 'foo-package', 'bar-package' ]
- [ ['one-package', 'two-package' ]]
- [ ['red-package'], ['blue-package']]

注册变量使用循环

- shell: echo "{{ item }}"
with_items:
- one
- two
register: echo

- name: Fail if return code is not 0
fail:
msg: "The command ({{ item.cmd }}) did not have a 0 return code"
when: item.rc != 0
with_items: "{{ echo.results }}"

循环主机清单

# 输出所有主机清单里的主机
- debug: msg={{ item }}
with_items: "{{ groups['all'] }}"
# 输出所有执行的主机
- debug: msg={{ item }}
with_items: play_hosts

#输出所有主机清单里的主机
- debug: msg={{ item }}
with_inventory_hostnames: all

# 输出主机清单中不在www中的所有主机
- debug: msg={{ item }}
with_inventory_hostnames: all:!www

改变循环的变量项

# main.yml
- include: inner.yml
with_items:
- 1
- 2
- 3
loop_control:
loop_var: outer_item
# inner.yml
- debug: msg="outer item={{ outer_item }} inner item={{ item }}"
with_items:
- a
- b
- c

更多文章请看 Ansible 专题文章总览

作者：lework
链接：http://www.jianshu.com/p/04516cbba336
來源：简书
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