handlers
接上一篇文章 Ansible Playbooks 介绍 和 使用 一 继续说明
用于当关注的资源发生变化时采取一定的操作。
notify
这个action
可用于在每个play的最后被处罚,这样可以避免多次有改变时每次都执行指定的操作,取而代之,尽在所有的变化发生完成后一次性执行指定的操作。在notify中列出的操作成为handler。
例如:
- name: template configuration file
template: src=template.j2 dest=/etc/foo.conf
notify:
- restart memcached
- restart apache
handler是task列表,这些task与前述task并没有本质上的不同。
handlers:
- name: restart memcached
service: name=memcached state=restarted
- name: restart apache
service: name=httpd state=restarted
playbook 案例 2 handlers
应用场景
在webservs组安装httpd服务,默认启动httpd监听的是
80
端口
步骤
- 创建一个配置安装httpd服务的playbook,并配置开机器启动等相关操作
- 执行httpd.yml
- 修改配置文件httpd.conf中的端口为8080
- 再次执行httpd的playbook文件
首先创建httpd.yml文件
[root@node01 ansible]# pwd
/etc/ansible
[root@node01 ansible]# cat httpd.yml
- hosts: webservs
remote_user: root
tasks:
- name: install httpd packge
yum: name=httpd state=present
- name: configuration file for httpd
copy: src=/etc/ansible/conf/httpd.conf dest=/etc/httpd/conf/httpd.conf
- name: start httpd service
service: name=httpd enabled=true state=started
创建配置文件目录,并拷贝httpd.conf
[root@node01 ansible]# pwd
/etc/ansible
[root@node01 ansible]# mkdir conf
[root@node01 ansible]# cp /etc/httpd/conf/httpd.conf conf/
[root@node01 ansible]# vim conf/httpd.conf
执行httpd.yuml的playbook
[root@node01 ansible]# ansible-playbook httpd.yml
PLAY [webservs] ***********************************************************************************************************
TASK [Gathering Facts] ****************************************************************************************************
ok: [10.0.0.65]
TASK [install httpd packge] ***********************************************************************************************
changed: [10.0.0.65]
TASK [configuration file for httpd] ***************************************************************************************
ok: [10.0.0.65]
TASK [start httpd service] ************************************************************************************************
changed: [10.0.0.65]
PLAY RECAP ****************************************************************************************************************
10.0.0.65 : ok=4 changed=2 unreachable=0 failed=0
验证:
[root@node01 ansible]# ansible webservs -a 'rpm -qa httpd'
10.0.0.65 | CHANGED | rc=0 >>
httpd-2.4.6-80.el7.centos.1.x86_64
[root@node01 ansible]# ansible webservs -m shell -a 'netstat -lntup | grep 80'
10.0.0.65 | CHANGED | rc=0 >>
tcp6 0 0 :::80 :::* LISTEN 31354/httpd
修改ansible服务端下httpd.conf配置文件中的端口为8080,然后重新执行
[root@node01 ansible]# egrep '^Listen' conf/httpd.conf
Listen 8080
[root@node01 ansible]# ansible-playbook httpd.yml
PLAY [webservs] ***********************************************************************************************************
TASK [Gathering Facts] ****************************************************************************************************
ok: [10.0.0.65]
TASK [install httpd packge] ***********************************************************************************************
ok: [10.0.0.65]
TASK [configuration file for httpd] ***************************************************************************************
changed: [10.0.0.65]
TASK [start httpd service] ************************************************************************************************
ok: [10.0.0.65]
PLAY RECAP ****************************************************************************************************************
10.0.0.65 : ok=4 changed=1 unreachable=0 failed=0
[root@node01 ansible]# ansible webservs -m shell -a 'netstat -lntup | grep httpd'
10.0.0.65 | CHANGED | rc=0 >>
tcp6 0 0 :::80 :::* LISTEN 31354/httpd
[root@node01 ansible]# ansible webservs -m shell -a 'egrep "^Listen" /etc/httpd/conf/httpd.conf'
10.0.0.65 | CHANGED | rc=0 >>
Listen 8080
最后可以看到,虽然远程主机的配置文件中的端口修改了,但实际监听的端口没有变,说明httpd没有重启
此时就需要用handlers,来监听当有类似于这样的配置文件操作变更的时候,就需要重启这样的操作,
下面修改httpd.yml中的内容
[root@node01 ansible]# cat httpd.yml
- hosts: webservs
remote_user: root
tasks:
- name: install httpd packge
yum: name=httpd state=present
- name: configuration file for httpd
copy: src=/etc/ansible/conf/httpd.conf dest=/etc/httpd/conf/httpd.conf
notify:
- restart httpd
- name: start httpd service
service: name=httpd enabled=true state=started
handlers:
- name: restart httpd
service: name=httpd state=restarted
再次把httpd.conf中的端口改成808,然后再次执行
[root@node01 ansible]# egrep '^Listen' conf/httpd.conf
Listen 808
[root@node01 ansible]# ansible-playbook httpd.yml
PLAY [webservs] ***********************************************************************************************************
TASK [Gathering Facts] ****************************************************************************************************
ok: [10.0.0.65]
TASK [install httpd packge] ***********************************************************************************************
ok: [10.0.0.65]
TASK [configuration file for httpd] ***************************************************************************************
changed: [10.0.0.65]
TASK [start httpd service] ************************************************************************************************
ok: [10.0.0.65]
RUNNING HANDLER [restart httpd] *******************************************************************************************
changed: [10.0.0.65]
PLAY RECAP ****************************************************************************************************************
10.0.0.65 : ok=5 changed=2 unreachable=0 failed=0
[root@node01 ansible]# ansible webservs -m shell -a 'netstat -lntup | grep httpd'
10.0.0.65 | CHANGED | rc=0 >>
tcp6 0 0 :::808 :::* LISTEN 32212/httpd
最后可以看到,远程主机的httpd服务监听的端口已经变成了808。
vars 变量
在playbook中使用变量,可以直接在playbook中直接定义变量,也可以在其他模板中定义变量,在playbook文件中饮用
下面以httpd.yml为例,在文件中增加vars变量
[root@node01 ansible]# cat httpd.yml
- hosts: webservs
remote_user: root
vars:
- package: httpd
- service: httpd
tasks:
- name: install httpd package
yum: name={{ package }} state=present
- name: configuration file for httpd
copy: src=/etc/ansible/conf/httpd.conf dest=/etc/httpd/conf/httpd.conf
notify:
- restart httpd
- name: start httpd service
service: name={{ service }} enabled=true state=started
handlers:
- name: restart httpd
service: name={{ service }} state=restarted
从上面的定义可以看出,变量的引用是通过{{ }}
两个大括号来的
下面看下重新执行一下,看下效果
[root@node01 ansible]# ansible-playbook httpd.yml
PLAY [webservs] ***********************************************************************************************************
TASK [Gathering Facts] ****************************************************************************************************
ok: [10.0.0.65]
TASK [install httpd package] **********************************************************************************************
ok: [10.0.0.65]
TASK [configuration file for httpd] ***************************************************************************************
ok: [10.0.0.65]
TASK [start httpd service] ************************************************************************************************
ok: [10.0.0.65]
PLAY RECAP ****************************************************************************************************************
10.0.0.65 : ok=4 changed=0 unreachable=0 failed=0
可以看到都是OK,说明变量引用成功了
setup facts 变量使用
playbook也可以直接引用facts中获取的远程主机信息的变量来使用
案例
首先来查看
[root@node01 ansible]# ansible webservs -m setup | head
10.0.0.65 | SUCCESS => {
"ansible_facts": {
"ansible_all_ipv4_addresses": [
"10.0.0.65"
],
"ansible_all_ipv6_addresses": [
"fe80::20c:29ff:fe07:47f6"
],
"ansible_apparmor": {
"status": "disabled"
这里就使用变量:ansible_all_ipv4_addresses 来调用使用
[root@node01 ansible]# cat test.yml
- hosts: webservs
remote_user: root
tasks:
- name: copy file
copy: content="{{ ansible_all_ipv4_addresses }}" dest=/tmp/vars.ans
[root@node01 ansible]# ansible-playbook test.yml
PLAY [webservs] ***********************************************************************************************************
TASK [Gathering Facts] ****************************************************************************************************
ok: [10.0.0.65]
TASK [copy file] **********************************************************************************************************
changed: [10.0.0.65]
PLAY RECAP ****************************************************************************************************************
10.0.0.65 : ok=2 changed=1 unreachable=0 failed=0
[root@node01 ansible]# ansible webservs -a 'cat /tmp/vars.ans'
10.0.0.65 | CHANGED | rc=0 >>
["10.0.0.65"]
从上面最后输出的结果来看,变量的调用成功。
inventory 中定义变量
同样也可以在inventory中定义变量,然后在playbook中引用
案例
修改inventory文件hosts
[root@node01 ansible]# cat hosts
# This is the default ansible 'hosts' file.
#
# It should live in /etc/ansible/hosts
#
# - Comments begin with the '#' character
# - Blank lines are ignored
# - Groups of hosts are delimited by [header] elements
# - You can enter hostnames or ip addresses
# - A hostname/ip can be a member of multiple groups
[webservs]
10.0.0.65 testvars="10.0.0.65"
[dbservs]
10.0.0.66 testvars="10.0.0.66"
上面给个主机定义了 testvars变量
下面来引用,修改playbook文件
[root@node01 ansible]# cat test.yml
- hosts: webservs, dbservs
remote_user: root
tasks:
- name: copy file
copy: content="{{ ansible_all_ipv4_addresses }}
{{ testvars }}" dest=/tmp/vars.ans
[root@node01 ansible]# ansible-playbook test.yml
PLAY [webservs, dbservs] **************************************************************************************************
TASK [Gathering Facts] ****************************************************************************************************
ok: [10.0.0.65]
ok: [10.0.0.66]
TASK [copy file] **********************************************************************************************************
changed: [10.0.0.66]
changed: [10.0.0.65]
PLAY RECAP ****************************************************************************************************************
10.0.0.65 : ok=2 changed=1 unreachable=0 failed=0
10.0.0.66 : ok=2 changed=1 unreachable=0 failed=0
[root@node01 ansible]# ansible all -a 'cat /tmp/vars.ans'
10.0.0.66 | CHANGED | rc=0 >>
[u'10.0.0.66']
10.0.0.66
10.0.0.65 | CHANGED | rc=0 >>
[u'10.0.0.65']
10.0.0.65
从上面最后的输出结果可以看出,引用成功。
条件测试
如果需要根据变量、facts或此前任务的执行结果来为某task执行与否的前提时要用到条件测试。
when 语句
在task后面添加when子句即可使用条件测试;when语句支持jinja2表达式语法,例如:
tasks:
- name: "shutdown Debian flavored systems"
command: /sbin/shutdown -h now
when: ansible_os_family == "Debian"
when 语句中还可以使用jinja2的太多filter,例如要忽略此前某语句的错误并基于其结果(failed或者sucess)运行后面指定的语句,可使用类似如下的形式:
tasks:
- command: /bin/false
register: result
ignore_errors: True
- command: /bin/something
when: result | failed
- command: /bin/something_else
when: result | success
- command: /bin/still/something_else
when: result | skipped
此外 when语句中还可以使用facts或playbook中定义的变量。
案例
判断当主机名为node02的时候,添加一个node02的新用户,否则其他机器不添加
首先使用ansible查看所有主机的主机名:
[root@node01 ansible]# ansible all -m setup | grep ansible_fqdn
"ansible_fqdn": "node02",
"ansible_fqdn": "node03",
定义和执行playbook文件
[root@node01 ansible]# cat cond.yml
- hosts: all
remote_user: root
vars:
- username: node02
tasks:
- name: create {{ username }} user
user: name={{ username }}
when: ansible_fqdn == "node02"
[root@node01 ansible]# ansible-playbook cond.yml
PLAY [all] ****************************************************************************************************************
TASK [Gathering Facts] ****************************************************************************************************
ok: [10.0.0.65]
ok: [10.0.0.66]
TASK [create node02 user] *************************************************************************************************
skipping: [10.0.0.66]
changed: [10.0.0.65]
PLAY RECAP ****************************************************************************************************************
10.0.0.65 : ok=2 changed=1 unreachable=0 failed=0
10.0.0.66 : ok=1 changed=0 unreachable=0 failed=0
[root@node01 ansible]# ansible all -a 'grep node02 /etc/passwd'
10.0.0.66 | FAILED | rc=1 >>
non-zero return code
10.0.0.65 | CHANGED | rc=0 >>
node02:x:1002:1002::/home/node02:/bin/bash
从上最后执行的结果来看,when的条件测试判断成功。
迭代
当有需要重复性执行的任务时,可以使用迭代机制,其使用格式为将需要迭代的内容定义为item变量,并通过with_items语句来指明迭代的元素列表即可。例如:
- name: add several users
user: name={{ item }} state=present groups=wheel
with_items:
- testuser1
- testuser2
事实上,with_items中可以使用元素还可以为hashes,例如:
- name: add several users
user: name={{ item }} state=present groups={{ item.groups }}
with_items:
- { name: 'testuser1', group: 'wheel' }
- { name: 'testuser2', group: 'root' }
templates 模板
在某个服务的配置文件中,预先定义好需要变更的变量,然后在执行playbook的时候,向定义好的配置文件中传入参数,可灵活修改;
如http服务,一个http监听80端口,另一个监听8080端口,则可以使用
案例
以httpd的配置文件为例,对其进行修改
[root@node01 ansible]# pwd
/etc/ansible
[root@node01 ansible]# mkdir templates
[root@node01 ansible]# cp /etc/httpd/conf/httpd.conf templates/httpd.conf.j2
[root@node01 ansible]# egrep "^Listen|^ServerName" templates/httpd.conf.j2
Listen {{ http_port }}
ServerName {{ ansible_fqdn }}
然后修改inventory文件中增加变量
[root@node01 ansible]# cat /etc/ansible/hosts
# This is the default ansible 'hosts' file.
#
# It should live in /etc/ansible/hosts
#
# - Comments begin with the '#' character
# - Blank lines are ignored
# - Groups of hosts are delimited by [header] elements
# - You can enter hostnames or ip addresses
# - A hostname/ip can be a member of multiple groups
[webservs]
10.0.0.65 http_port=80
[dbservs]
10.0.0.66 http_port=8080
定义playbook文件
[root@node01 ansible]# cat apache.yml
- hosts: webservs dbservs
remote_user: root
vars:
- package: httpd
- service: httpd
tasks:
- name: install httpd package
yum: name={{ package }} state=present
- name: configuration file for httpd
template: src=/etc/ansible/templates/httpd.conf.j2 dest=/etc/httpd/conf/httpd.conf
notify:
- restart httpd
- name: start httpd service
service: name={{ service}} enabled=true state=started
handlers:
- name: restart httpd
service: name={{ service }} state=restarted
执行
[root@node01 ansible]# ansible-playbook apache.yml
PLAY [webservs dbservs] ***************************************************************************************************
TASK [Gathering Facts] ****************************************************************************************************
ok: [10.0.0.66]
ok: [10.0.0.65]
TASK [install httpd package] **********************************************************************************************
ok: [10.0.0.65]
ok: [10.0.0.66]
TASK [configuration file for httpd] ***************************************************************************************
changed: [10.0.0.65]
changed: [10.0.0.66]
TASK [start httpd service] ************************************************************************************************
changed: [10.0.0.65]
changed: [10.0.0.66]
RUNNING HANDLER [restart httpd] *******************************************************************************************
changed: [10.0.0.66]
changed: [10.0.0.65]
PLAY RECAP ****************************************************************************************************************
10.0.0.65 : ok=5 changed=3 unreachable=0 failed=0
10.0.0.66 : ok=5 changed=3 unreachable=0 failed=0
[root@node01 ansible]# ansible all -m shell -a 'egrep "^Listen|^ServerName" /etc/httpd/conf/httpd.conf'
10.0.0.65 | CHANGED | rc=0 >>
Listen 80
ServerName node02
10.0.0.66 | CHANGED | rc=0 >>
Listen 8080
ServerName node03
[root@node01 ansible]# ansible all -m shell -a 'netstat -lntup | grep httpd'
10.0.0.65 | CHANGED | rc=0 >>
tcp6 0 0 :::80 :::* LISTEN 34619/httpd
10.0.0.66 | CHANGED | rc=0 >>
tcp6 0 0 :::8080 :::* LISTEN 29274/httpd
从上个最后的执行结果可以看出,template中定义的端口已经生效了。
tags
当一个playbook需要运行多次是,可以在playbook文件中的一个tasks中,定义一个tags,在第二次运行时,可以指定tags,只运行其中一个tasks。
案例
重新定义playbook文件
[root@node01 ansible]# cat apache.yml
- hosts: webservs dbservs
remote_user: root
vars:
- package: httpd
- service: httpd
tasks:
- name: install httpd package
yum: name={{ package }} state=present
- name: configuration file for httpd
template: src=/etc/ansible/templates/httpd.conf.j2 dest=/etc/httpd/conf/httpd.conf
tags:
- conf
notify:
- restart httpd
- name: start httpd service
service: name={{ service}} enabled=true state=started
handlers:
- name: restart httpd
service: name={{ service }} state=restarted
[root@node01 ansible]# cat hosts
# This is the default ansible 'hosts' file.
#
# It should live in /etc/ansible/hosts
#
# - Comments begin with the '#' character
# - Blank lines are ignored
# - Groups of hosts are delimited by [header] elements
# - You can enter hostnames or ip addresses
# - A hostname/ip can be a member of multiple groups
[webservs]
10.0.0.65 http_port=808
[dbservs]
10.0.0.66 http_port=800
运行:
[root@node01 ansible]# ansible-playbook apache.yml --tags="conf"
PLAY [webservs dbservs] ***************************************************************************************************
TASK [Gathering Facts] ****************************************************************************************************
ok: [10.0.0.66]
ok: [10.0.0.65]
TASK [configuration file for httpd] ***************************************************************************************
changed: [10.0.0.65]
changed: [10.0.0.66]
RUNNING HANDLER [restart httpd] *******************************************************************************************
changed: [10.0.0.66]
changed: [10.0.0.65]
PLAY RECAP ****************************************************************************************************************
10.0.0.65 : ok=3 changed=2 unreachable=0 failed=0
10.0.0.66 : ok=3 changed=2 unreachable=0 failed=0
从上面运行的结果来看,安装和启动没有运行,只运行了配置修改和重启。
说明
特殊的 tags: always
表示无论指定或者不指定,都会运行对应的tasks