Automated operation and maintenance of the variables used Ansible

1, Playbook variable

ansible use variables, allow us to work more flexible

Define the variable

Variable names should consist of letters, numbers, underscores, variable names need to start with a letter, ansible built-in keyword can not be used as a variable name use

2, Playbook variable definitions

When using the keyword vars variables can be defined in the current playbook, so that we want to use a variable, you need to reference the corresponding variable name, use {{name}} variable can refer to the corresponding variable.

A simple definition of variables

- hosts: all
  vars:     #定义变量
    file_name: jsn_yaml_vars    #变量名(随意)：file_name，变量的内容：jsn_yaml_vars
  tasks:    #{{ file_name }}引用上面定义的变量
  - name: 应用变量名：file_name
    file: path=/tmp/{{ file_name }} state=touch

Define multiple variables

- hosts: all
  vars:   
    t1: v1
    t2: v2

In addition to the above grammar, syntax sequences can also be custom variable speed YAML

- hosts: all
  vars:   
    - t1: v1
    - t2: v2

When defining a variable, it may also be similar to the "Properties" define variable

- hosts: 10.4.7.7
  vars:
    nginx:
      proxy_1: /etc/nginx/conf.d/nginx_1.proxy
      proxy_2: /etc/nginx/conf.d/nginx_2.proxy
  tasks:
  - name: task1
    file:
      path: "{{ nginx.proxy_1 }}"
      state: touch
  - name: task1
    file:
      path: "{{ nginx['proxy_2'] }}" # 第二种引用变量.属性的方法
      state: touch

Node: Note that we use double quotes in the use of variables, but did not use double quotation marks when referring to variables in the example at the beginning of the most, because it is the first instance when the variable is referenced, and not in the beginning of the position path=/tmp/{{ file_name }}, so do not need to double quotes, but path: "{{ nginx.proxy_1 }}"in the beginning of the variable position, you need to double quotes

Define the variable written to the specified file and then referenced in the playbook in

1. Create nginx_vars.yaml file, define the variable

nginx:
  proxy_1: /etc/nginx/conf.d/nginx_1.proxy
  proxy_2: /etc/nginx/conf.d/nginx_2.proxy

2. After nginx_vars.yaml variables defined in the file, the file can be introduced into the variable contained in the playbook

- hosts: 10.4.7.7
  vars_files:
    - ~/nginx_vars.yaml
  tasks:
  - name: task1
    file:
      path: "{{ nginx.proxy_1 }}"
      state: touch
  - name: task1
    file:
      path: "{{ nginx['proxy_2'] }}" 
      state: touch

Used in this embodiment vars_filesis introduced corresponding to the keyword variable file, and then using the variables in the file, the file keyword can introduce a variable may be introduced into a plurality of variable files, each file will need to be introduced -at the beginning, varsand vars_filessimultaneously use

When playbook reference variable, execution of the specified variable assignment

1. Create yaml

- hosts: all
  tasks:
  - name: Create New File
    file: path=/tmp/{{ file_name }} state=touch

When parameters 2.playbook execution of --extra-varsthe specified assignment to a variable

$ ansible-playbook f1.yaml --extra-vars "file_name=jsn_extra-vars"

3, Playbook variable registration

register keyword can be stored in the specified output of the command variable to a custom in which there is a great use of that we need to judge the implementation of an action or a command, how to make the appropriate response processing (perform other ansible statement), also used it.

register simple and practical

1. The f1.yamldocument reads as follows

- hosts: 10.4.7.7
  tasks:
    - name: register vars
      shell: hostname
      register: System_Status
    - name: display vars
      debug: msg={{ System_Status.stdout }}

2. Perform playbook

[root@m01 ~]#  ansible-playbook f1.yaml

PLAY [10.4.7.7] ****************************************************************

TASK [Gathering Facts] *********************************************************
ok: [10.4.7.7]

TASK [register vars] ***********************************************************
changed: [10.4.7.7]

TASK [display vars] ************************************************************
ok: [10.4.7.7] => {
    "msg": "web01"
}

PLAY RECAP *********************************************************************
10.4.7.7                   : ok=3    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

• The first shell after the implementation, use register to get the data System_Statusin
• System_StatusIt is a key / value dictionary
• debug output System_Status.stdout的specific content

register production example

Sda1 I need to determine whether there is, if there is a copy of the executable file

- hosts: 10.4.7.7
  tasks:
    - name:  Create a register to represent the status if the /dev/sda1 exsited
      shell: df -h  | grep sda1
      register: dev_sda1_result
      ignore_errors: True
      
    - name: Copy test.sh to all hosts
      copy: src=/root/test.sh dest=/tmp/test.sh mode=755
      when: dev_sda1_result.rc == 0 

When df -h | grep sda1the execution, will dev_sda1_resultwrite the results, and then dev_sda1_result.rc rc is returned in command of the state, nonzero if unsuccessful, ignore_errorsthe keyword must be set to True, or if the command is not successful, that is echo $?not 0, then ansible statement following the statement will not be executed, causing the program to abort.

Multi-conditional register

Then whenwith andor orcombined judgment. For example, when one of two conditions for success:

    - name: Copy test.sh to all hosts
      copy: src=/root/test.sh dest=/tmp/test.sh mode=755
      when: ( dev_sda1_result.rc == 0 ) or ( dev_sda2_result.rc == 0  )