when条件语句

- name: Install vim
  hosts: all
  tasks:
    - name: Install VIM via yum
      yum: 
        name: vim-enhanced 
        state: installed
      when: ansible_os_family =="RedHat"      
    - name: Install VIM via apt
      apt: 
        name: vim 
        state: installed
      when: ansible_os_family =="Debian" 
    - name: Unexpected OS family
      debug: msg="OS Family {{ ansible_os_family }} is not supported"
      when: not ansible_os_family =="RedHat" or ansible_os_family =="Debian"

- hosts: node1
  tasks:
     - name: debug memory size
       debug:
          msg: "{{ inventory_hostname }} memory size is {{ ansible_memtotal_mb }}"
       when: ansible_memtotal_mb >= 4096  #比较数值大小

条件判断

条件判断与block：

例子：

-hosts: node1
 tasks:
  -block: 
     -name: install apache
      yum: 
        name: httpd
        state: present
     -name: started apache
      service: 
        name: httpd
        state: started
        enable: yes
  when: ansible_os_family == "RedHat"

rescue

当block执行失败时，rescue中的任务才会被执行；block除了能跟和when一起使用之外，还能进行错误处理。这个时候就需要用到rescue关键字：

-hosts: test
 tasks: 
    -block: 
       -shell: 'ls /testdir'
     rescue: 
       -debug: 
          msg: '/testdir is not exits'

always

无论block执行成功还是失败，always中的任务都会被执行

-hosts: test
 tasks: 
     -block:
       -shell: 'ls /testdir'
      rescue:
       -debug:
         msg: '/testdir is not exists'
      always: 
        -debug:
          msg: 'This task always executes'

判断变量：

defined：判断变量是否已定义，已定义则返回真
undefined：判断变量是否未定义，未定义则返回真
none：判断变量的值是否为空，如果变量已定义且值为空，则返回真

例子：

- hosts: test
  gather_facts: no
  vars:
    testvar: "test"
    testvar1:
  tasks:
    - debug:
        msg: "testvar is defined"
      when: testvar is defined
    - debug:
        msg: "testvar2 is undefined"
      when: testvar2 is undefined
    - debug:
        msg: "testvar1 is none"
      when: testvar1 is none

判断文件类型：

file：判断指定路径是否为一个文件，是则为真
directory：判断指定路径是否为一个目录，是则为真
link：判断指定路径是否为一个软链接，是则为真
mount：判断指定路径是否为一个挂载点，是则为真
exists：判断指定路径是否存在，存在则为真
特别注意：关于路径的所有判断均是判断主控端上的路径，而非被控端上的路径

- hosts: test
  vars:
    testpath: /testdir
  tasks:
    - debug:
        msg: "file exist"
      when: testpath is exists
- hosts: test
  vars:
    testpath: /testdir1
  tasks:
    - debug:
        msg: "file not exist"
      when: not testpath is exists

[admin@ansible ansible]$ cat when3.yml
- hosts: node1
  vars:
     filepath: /home/admin/ansible/ansible.cfg   
  tasks:
     - debug:
         msg: "the file is exists"
       when: filepath is exists  #filepath是主控端的文件

- hosts: test
  gather_facts: no
  vars:
    testpath1: "/testdir/test"
    testpath2: "/testdir"
  tasks:
    - debug:
        msg: "file"
      when: testpath1 is file
    - debug:
        msg: "directory"
      when: testpath2 is directory

判断执行结果：

ok：目标状态与期望值一致，没有发生变更
change或changed：目标发生变更，无论成功还是失败，都是change
sucess或succeeded：目标状态与期望值一致，或者任务执行成功
failure或failed：任务执行失败
skip或skipped：任务被跳过

- hosts: test
  tasks:
    - shell: 'cat /testdir/aaa'
      register: result
      ignore_errors: true
    - debug:
        msg: "success"
      when: result is success
    - debug:
        msg: "failed"
      when: result is failure
    - debug:
        msg: "changed"
      when: result is change
    - debug:
        msg: "skip"
      when: result is skip

判断字符串

lower：判断字符串中的所有字母是否都是小写，是则为真
upper：判断字符串中的所有字母是否都是大写，是则为真

- hosts: node1
  gather_facts: no
  vars: 
    str1: "abc"
    str2: "ABC"
  tasks:
    - debug:
        msg: "str1 is all lowercase"
      when: str1 is lower
    - debug:
        msg: "str2 is all uppercase"
      when: str2 is upper

判断整数：

even：判断数值是否为偶数，是则为真
odd：判断数值是否为奇数，是则为真
divisibleby(num)：判断是否可以整除指定的数值，是则为真

- hosts: node1
  gather_facts: no
  vars: 
    num1: 6
    num2: 8 
    num3: 15
  tasks:
    - debug: 
        msg: "num1 is an even number"
      when: num1 is even
    - debug:
        msg: "num2 is an odd number"
      when: num2 is odd
    - debug:
        msg: "num3 can be divided exactly by"
      when: num3 is divisibleby(3)

其他条件测试：

subset 判断一个list是不是另一个list的子集：when: a is subset(b)
superset 判断一个list是不是另一个list的父集：when: b is superset(a)
in 判断一个字符串是否存在于另一个字符串中，也可用于判断某个特定的值是否存在于列表中
supported_distros:
- RedHat
- CentOS
when: ansible_distribution in supported_distros
string 判断对象是否为一个字符串，是则为真 when: var1 is string
number 判断对象是否为一个数字，是则为真 when: var3 is number

- hosts: node1
  vars:
     package:
         - httpd
         - nginx
     string: abc
     num: 100
  tasks:
     - name: nginx is in package
       debug:
           msg: "nginx is in package"
       when: '"nginx" in package'
     - debug:
         msg: a is in abc
       when: '"a" in string'
     - debug:
          msg: "{{ inventory_hostname }} is in web group"
       when: '"web" in group_names'
     - debug:
         msg: "{{ string }} is string"
       when: 'string is string'
     - debug:
         msg: "{{ num }} is number"
       when: 'num is number'

- hosts: node1
  tasks: 
    - block:
      - name: install httpd
        yum: 
            name: httpd
            state: present
      - name: started httpd
        service:
            name: httpd
            enabled: yes
            state: started
      rescue: 
        - name: install nginx
          yum:
            name: nginx
            state: present
      always:
        - name: install mariadb
          yum:
             name: mariadb*
             state: present
      when: "ansible_os_family == 'RedHat'"

playbook循环语句

with_items:循环列表

- hosts: node1
  vars:
     users:
        - username: user11
          useruid: 1111
        - username: user22
          useruid: 1112
        - username: user33
          useruid: 1113
  tasks:
    - name: create user
      user:
         name: "{{ item.username }}"
         uid: "{{ item.useruid }}"
         state: present
      with_items: "{{ users }}"
    - name: debug item
      debug:
         msg: "{{ item }}"
      with_items: "{{ users }}"

with_dict:循环字典

- hosts: node1
  gather_facts: no
  vars:
    users:
      alice:
        name: Alice Appleworth
        telephone: 123-456-7890
      bob:
        name: Bob Bananarama
        telephone: 987-654-3210
  tasks:
    - name: display user telephone
      debug:
        msg: "{{ item.value.name }}  telephone is  {{ item.value.telephone }}"
      with_dict: "{{ users }}"

loop默认循环列表

loop: “{{ users }}”

如果循环字典，就需要进行转换
loop: “{{users | dict2items }}”

fail主动错误

使用fail模块中断playbook输出

- hosts: test
  tasks:
    - shell: echo "Just a test--error" 
      register: result
    - fail:
        msg: "Conditions established,Interrupt running playbook"
      when: "'error' in result.stdout"
    - debug:
        msg: "I never execute,Because the playbook has stopped"


[admin@ansible ansible]$ cat fail.yml 
- hosts: node1
  tasks:
    - shell: echo "Just a test--error" 
      register: result
      failed_when: "'error' in result.stdout"
    - debug:
        msg: "I never execute,Because the playbook has stopped"

linux

8.条件语句与循环语句