Write a simple shell script
Automatically add 3 users and ask: a b c
#!/bin/bash #This line is only a comment and has no special meaning for i in a b c;do useradd $i;done
Add password redhat for all users
#!/bin/bash for a in a b c; do echo redhat |passwd --stdin $a ;done
Loop loop of playbook
---
- name: loop loop
hosts: all
tasks:
- name: create group
group:
name: "{{item.groupname}}" #Where item means to find loop
loop:
- groupname: abc
- name: create user
user:
name: "{{item.username}}"
state: present
groups: "{{item.group}}"
uid: "{{item.uid}}"
loop:
- username: a
group: abc
uid: 2500
- username: b
group: abc
uid: 2501
- username: c
uid: 2502
group: abc
Conditional expression of when:
1. Judge the value of the variable
example:
Generate a setup
ansible all -m setup >111.txt
Determine the free cache size of the target host:
---
- name: test
hosts: all
tasks:
- name: Print free cache
debug:
msg: "{{ansible_swapfree_mb}}"
when: ansible_swapfree_mb > 2000
2. Judge whether the variable exists
Use "is defined" and "is undefined" to determine whether the variable exists
Example: judge whether there is an sdb disk on the target host. If so, output the size of the sdb disk
msg: "{{ ansible_devices.sdb.size}}"
when: ansible_devices.sdb is defined
3. Judge whether the variable is in the specified list
Use "in" to judge
Determine whether the host name is in the mysql group
when ansible_hostname in group.mysql
A complete instance
1. Create a locker.yml first
Create two passwords, as shown below
pw_developer: redhat pw_manager: redhat
2. Create another passwd.txt to store the password of the encrypted locker
snfwelknfwlnfknwefdsif(Just lose)
3. Use the anisble value command to encrypt the locker file
ansible-vault encrypt --vault-password-file=passwd.txt locker.yml
4.vim user_list.yml
aaa:
- username: eoe
uid: 3600
job: a
- username: pop
uid: 3691
job: a
5 vim user.yml
---
- name: 111
hosts: all
vars_files:
- user_list.yml
- locker.yml
tasks:
- name: create group
group:
name: aaa
state: present
- name: create user
user:
name: "{{item.username}}"
state: present
uid: "{{item.uid}}"
password: "{{pw_manager | password_hash('sha512')}}" #Using hash algorithm to encrypt pw_manager password
loop: "{{aaa}}" #Call user_ aaa in list.yml
when: item.job == 'a' #Judge whether the job value is a. if yes, execute create user
handler trigger
A simple handler trigger example:
---
- name: test
hosts: all
tasks:
- name: install httpd
yum:
name: httpd
state: present
- name: start httpd
service:
name: httpd
state: started
notify: stopped httpd
handlers:
- name: stopped httpd #Only the same tasks as the name of notify will be triggered
service:
name: httpd
state: stopped
- name: remove httpd #It will not be triggered here because the name is different from notify
yum:
name: httpd
state: remove
exception handling
1. Ignore errors
ignore_errors: yes errors can be ignored
2. block
In Ansible, you can use block to define multiple tasks as a block. A block block can be regarded as a group or a whole. We can judge the conditions of the whole block. When the conditions are established, all tasks in the block will be executed. Block can also be used in conjunction with rescue and always. Rescue can catch errors in the tasks in the block. When any task in the block fails, it will execute the tasks in rescue. Always means that any task in always will be executed regardless of whether the task in the block block is successfully executed
Business. "When there is an error in the block, execute rescue"
Example 1:
Judge the requirements of the block block: if there is a disk vdb, create a 4GB partition on the vdb. If there is not enough 4GB space, create a 2GB partition.
Used module parted: disk partition and partition sizing tool
---
- hosts: all
tasks:
- block:
- name: create 4GiB part
parted:
device: /dev/vdb
number: 1
state: present
part_end: 4Gib
rescue:
- name: create 1 GiB part
parted:
device: /dev/vdb
number: 1
part_end: 2GiB
state: present
when: ansible_devices.vdb is defined
Example 2:
lvol creates, deletes, and dynamically changes the size of logical volumes.
Create a playbook named / home / Devops / adaptive / lv.yml, which will run on all managed nodes to perform the following tasks:
Create logical volumes that meet the following requirements:
Logical volumes are created in the research volume group
The logical volume name is data
The logical volume size is 1500MiB
Format logical volumes using the ext4 file system
If the requested logical volume size cannot be created, the error message Could not create logical volume of that size should be displayed and the size 800Mib should be used instead.
If the volume group research does not exist, the error message Volume group not exist should be displayed. Do not mount logical volumes in any way
Environment construction:
Prepare two virtual machines and add 5G hard disk respectively
Configure the first virtual machine
fdisk /dev/sdc n #establish p #primary Last sector : +840M t #Change partition type 82 #Linux swap t 8e #Linux LVM w #Save exit pvcreate /dev/sdc1 #Create physical volume sdc1 vgcreate research /dev/sdc1 #Create volume group research
The configuration of the second virtual machine is basically the same as that of the first one, except that the size of the primary partition is set to 1600M
Test on any virtual machine with ansible service:
---
- name: 111
hosts: all
tasks:
- debug:
mgs: "Volume group done not exist"
when: ansible_lvm.vgs.research is undefined
- block:
- name: create lv1500
lvol:
vg: research
lv: data
size: 1500M
rescue:
- debug:
msg: "could not create logical volume of that size"
- name: create lv800
lvol:
vg: research
lv: data
size: 800M
when: ansible_lvm.vgs.research is defined
always:
- name: create filesystem
filesystem:
dev: /dev/research/data
fstype: ext4