Ansible8:playbook cycle "Turn"

When using ansible for automating operations, it is unavoidable to repeat certain operations, such as adding several users, creating several MySQL users and giving them permissions, manipulating all files in a directory, and so on. Fortunately, the Playbook supports loop statements, which makes certain requirements very easy and prescriptive to implement.

1, With_items

With_items is the most basic and most commonly used looping statement in playbooks:

Tasks
-Name:secure config files
file:path=/etc/{{Item}} mode=0600 owner=root Group=root
With_items:
-MY.CNF
-Shadow
-Fstab

The above example shows that three files were created for my.cnf, shadow, Fstab

You can also assign a file list to a variable in advance, and then call it in a looping statement:

    with_items: "{{ somelist }}"

使用with_items迭代循环的变量可以是个单纯的列表，也可以是一个较为复杂 的数据结果，如字典类型：


tasks:

- name: add several users

  user: name={{ item.name }} state=present groups={{ item.groups }}

  with_items:

    - { name: ‘testuser1‘, groups: ‘wheel‘ }

    - { name: ‘testuser2‘, groups: ‘root‘ }

2、with_nested嵌套循环

Example:

Tasks

-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 ']

ITEM[0] is the value of the first list of loops [' Alice ', ' Bob ']. ITEM[1] is the value of the second list. Represents a loop that creates two users for Alice and Bob, and gives them all permissions on three databases.

You can also assign a user list to a variable beforehand:

Tasks

-Name:here, ' users ' contains the above list of employees

mysql_user:name={{item[0]}} priv={{item[1]}}.*:all append_privs=yes Password=foo

With_nested:

-"{{users}}"

-[' Clientdb ', ' employeedb ', ' Providerdb ']

3, With_dict

With_dict can traverse more complex data structures:

If you have the following variable contents:

Users

Alice

Name:alice Appleworth

telephone:123-456-7890

Bob

Name:bob Bananarama

telephone:987-654-3210

Now you need to output the user name and phone number for each user:

Tasks

-Name:print phone records

Debug:msg= "User {{Item.key}} is {{item.value.name}}} ({{item.value.telephone}})"

With_dict: "{{users}}"

4. with_fileglob File Matching traversal

You can specify a directory that uses With_fileglob to iterate through all the files in this directory, as shown in the following example:

Tasks




With_fileglob:


Assemble:src=/root/.sshkeys dest=/root/.ssh/authorized_keysmode=0600 owner=root group=root  

5. With_subelement traversing child elements

If you need to traverse a list of users now and create each user, you also need to configure each user to log in with a specific SSH key. The contents of the variable file are as follows:

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"

 

playbook中定义如下：

- 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

 

也可以遍历嵌套的子列表：

- 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

6、with_sequence循环整数序列

With_sequence can generate an auto-increment sequence of integers, you can specify the starting and ending values, or you can specify the growth step. The parameter is specified as Key=value, and format specifies the form of the output. The number can be decimal, 16 binary, octal:

-Hosts:all

Tasks

# Create Groups

-Group:name=evens State=present

-Group:name=odds State=present

# Create some test users

-user:name={{Item}} state=present Groups=evens

With_sequence:start=0 end=32 format=testuser%02d

# Create a series of directories with even numbers for some reason

-file:dest=/var/stuff/{{Item}} state=directory

with_sequence:start=4 end=16 stride=2 # Stride for specifying stride length

# a simpler the sequence plugin

# Create 4 groups

-group:name=group{{Item}} state=present

With_sequence:count=4

7、with_random_choice随机选择

Randomly take a value from the list:

-debug:msg={{Item}}

With_random_choice:

-"Go through the door"

-"Drink from the Goblet"

-"Press the red button"

-"Do Nothing"

8. Do-util Cycle

Example:

-Action:shell/usr/bin/foo

Register:result

Until:result.stdout.find ("All Systems go")! =-1

Retries:5

Delay:10

Executes the shell module repeatedly, stopping when the shell module executes the command output that contains "all systems Go". Retry 5 times, delay time 10 seconds. Retries Default value is 3,delay default is 5. The return value of the task is the return result of the last loop.

9. Cyclic Registration variables

When using register in a loop, the saved result contains the results keyword, which saves a list of the results of the module execution

-Shell:echo "{{Item}}"

With_items:

-One

-Double

Register:echo

The variable echo content is as follows:

{

"Changed": true,

"MSG": "All items Completed",

"Results": [

{

"Changed": true,

"cmd": "Echo \" One\ "",

"Delta": "0:00:00.003110",

"End": "2013-12-19 12:00:05.187153",

"Invocation": {

"Module_args": "Echo \" One\ "",

"Module_name": "Shell"

},

"Item": "One",

"RC": 0,

"Start": "2013-12-19 12:00:05.184043",

"StdErr": "",

"stdout": "One"

},

{

"Changed": true,

"cmd": "Echo \" Two\ "",

"Delta": "0:00:00.002920",

"End": "2013-12-19 12:00:05.245502",

"Invocation": {

"Module_args": "Echo \" Two\ "",

"Module_name": "Shell"

},

"Item": "Both",

"RC": 0,

"Start": "2013-12-19 12:00:05.242582",

"StdErr": "",

"stdout": "The Other"

}

]

}

The result of traversing a registered variable:

-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}}"

10. With_together Traversal Data Parallel collection

Example:

-Hosts:webservers

Remote_user:root

VARs

Alpha: [' A ', ' B ', ' C ', ' d ']

Numbers: [1,2,3,4]

Tasks

-debug:msg= "{{item.0}} and {{item.1}}"

With_together:

-"{{alpha}}"

-"{{numbers}}"

The result of the output is:

OK: [192.168.1.65] = (item=[' A ', 1]) + = {

"Item": [

"A",

1

],

"MSG": "A and 1"

}

OK: [192.168.1.65] = (item=[' B ', 2]) + = {

"Item": [

"B",

2

],

"MSG": "B and 2"

}

OK: [192.168.1.65] = (item=[' C ', 3]) + = {

"Item": [

"C",

3

],

"MSG": "C and 3"

}

OK: [192.168.1.65] = (item=[' d ', 4]) + = {

"Item": [

"D",

4

],

"MSG": "D and 4"

}

Loop modules are typically used in the following scenarios

1. A similar configuration module is repeated multiple times

2. Fact is a list

3. Create multiple files and then use assemble to synthesize a large file

4. Using With_fileglob to match specific file management

This article is from the "Nobody" blog, please be sure to keep this source http://breezey.blog.51cto.com/2400275/1757636

Ansible8:playbook cycle "Turn"