Linux自动化运维——5、Ansible中的任务执行控制
一.循环
循环迭代任务
1.简单循环
loop: ##赋值列表
- value1
- value2
- ...
{
{
item}} ##迭代变量名称
实例
---
- name: create file
hosts: all
tasks:
- name: file module
file:
name: /mnt/{
{
item}}
state: present
loop:
- westos_file1
- westos_file2
2.循环散列或字典列表
---
- name: create file
hosts: all
tasks:
- name: file module
service:
name: "{
{ item.name}}"
state: "{
{ item.state }}"
loop:
- name: httpd
state: started
- name: vsftpd
state: stopped
二.条件
when:
- 条件1
- 条件2
条件判断
= value == "字符串",value == 数字
< value < 数字
> value > 数字
<= value <= 数字
>= value >= 数字
!= value != 数字
is defined value value is defined 变量存在
is not defined value is not defined 变量不存在
in value is in value 变量为
not in value is not in value 变量不为
bool变量 为true value value的值为true
bool变量 false not value value的值为false
value in value2 value的值在value2列表中
多条条件组合
when：
条件1 and 条件2
- 条件1
- 条件2
when:
条件1 or 条件2
when: >
条件1
or
条件2
测试题：
建立playbook ~/ansibles/lvm.yml要求如下:
*建立大小为1500M名为exam_lvm的lvm 在westos组中
*如果westos不存在请输出:
vg westos is not exist
*如果westos大小不足1500M请输出：
vg westos is less then 1500M
并建立800M大小的lvm
---
- name: create a new device
hosts: all
tasks:
- name: check /dev/vdb
debug:
msg: /dev/vdb is not exist
when: ansible_facts['devices']['vdb'] is not defined
- name: create /dev/vdb1
block:
- name: check 2G /dec/vdb
parted:
device: /dev/vdb
number: 1
state: present
part_end: 2GiB
when: ansible_facts['devices']['vdb'] is defined
notify:
- Remove 2000M vdb1
- create 1500M vdb1
- create filesystem
- mount /dev/vdb1
rescue:
- name: create a 800M
parted:
device: /dev/vdb
number: 1
state: present
part_end: 800MiB
notify:
- create filesystem
- mount /dev/vdb1
when: ansible_facts['devices']['vdb'] is defined
always:
- name: create mount point
file:
path: /westos
state: directory
handlers:
- name: Remove 2000M vdb1
parted:
device: /dev/vdb
number: 1
state: absent
- name: create 1500M vdb1
parted:
device: /dev/vdb
number: 1
state: present
part_end: 1500MiB
- name: create filesystem
filesystem:
fstype: xfs
force: yes
device: /dev/vdb1
- name: mount /dev/vdb1
mount:
path: /westos
src: /dev/vdb1
fstype: xfs
state: mounted
三.触发器
notify: 触发器当遇到更改是触发handlers
handlers： 触发器触发后执行的动作
实例
---
- name: create virtualhost for web server
hosts: all
vars_files:
./vhost_list.yml
tasks:
- name: create document
file:
path: "{
{web2.document}}"
state: directory
- name: create vhost.conf
copy:
dest: /etc/httpd/conf.d/vhost.conf
content:
"\n\tServerName {
{web1.name}}\n\tDocumentRoot {
{web1.document}}\n\tCustomLog logs/{
{web1.name}}.log combined\n \n\n\n\tServerName {
{web2.name}}\n\tDocumentRoot {
{web2.document}}\n\tCustomLog logs/{
{web2.name}}.log combined\n "
notify:
restart apache
handlers:
- name: restart apache
service:
name: httpd
state: restarted
四.处理失败任务
1.ignore_errors
作用：当play遇到任务失败是会终止
ignore_errors: yes 将会忽略任务失败使下面的任务继续运行
实例
- name: test
dnf:
name: westos
state: latest
ignore_errors: yes
- name: create file
file:
path: /mnt/westos
state: touch
2.force_handlers
作用：当任务失败后play被终止也会调用触发器进程
实例
---
- name: apache change port
hosts: all
force_handlers: yes
vars:
http_port: 80
tasks:
- name: configure apache conf file
lineinfile:
path: /etc/httpd/conf/httpd.conf
regexp: "^Listen"
line: "Listen {
{ http_port }}"
notify: restart apache
- name: install error
dnf:
name: westos
state: latest
handlers:
- name: restart apache
service:
name: httpd
state: restarted
enabled: yes
3.changed_when
作用：控制任务在何时报告它已进行更改
实例
---
- name: apache change port
hosts: all
force_handlers: yes
vars:
http_port: 8080
tasks:
- name: configure apache conf file
lineinfile:
path: /etc/httpd/conf/httpd.conf
regexp: "^Listen"
line: "Listen {
{ http_port }}"
changed_when: true
notify: restart apache
handlers:
- name: restart apache
service:
name: httpd
state: restarted
enabled: yes
4.failed_when
作用：当符合条件时强制任务失败
---
- name: test
hosts: all
tasks:
- name: shell
shell: echo hello
register: westos
failed_when: "'hello' in westos.stdout"
5.block
block: ##定义要运行的任务
rescue: ##定义当block句子中出现失败任务后运行的任务
always： ##定义最终独立运行的任务
测试练习
建立playbook ~/westos.yml要求如下:
建立大小为1500M名为/dev/vdb1的设备
如果/dev/vdb不存在请输入:
/dev/vdb is not exist
如果/dev/vdb大小不足2G请输出：
/dev/vdb is less then 2G
并建立800M大小的/dev/vdb1
此设备挂载到/westos上
---
- name: create lvm
hosts: all
tasks:
- name: check /dev/vdb
debug:
msg: /dev/vdb is not exist
when: ansible_facts['devices']['vdb'] is not defined
- name: create /dev/vdb1
block:
- name: create 1500M
parted:
device: /dev/vdb
number: 1
state: present
part_end: 1500MB
when: ansible_facts['devices']['vdb'] is defined
rescue:
- name: create 800MB
parted:
device: /dev/vdb
number: 1
state: present
part_end: 800MB
when: ansible_facts['devices']['vdb'] is defined
always:
- name: mkfs.xfs /dev/vdb1
filesystem:
fstype: xfs
dev: /dev/vdb1
- name: mkdir /westos
file:
path: /westos
state: directory
- name: mount /dev/vdb1
mount:
path: /westos
src: /dev/vdb1
fstype: xfs
state: mounted
when: ansible_facts['devices']['vdb'] is defined