4 定时器基础
定时器从本质上来说就是stackstorm中的rule。
规则对trigger触发器到action(或工作流)做了映射。应用匹配的criteria并且
映射trigger payloads到动作的输入。
说白了rules包含trigger，action,criteria(可以不需要)3个部分，来将事件
的触发映射到动作的执行。
trigger是前置条件，如果触发，则继续查看criteria(如果存在的化)条件是否匹配，
如果匹配，则触action。
rule的主要格式如下:
name: 规则名称
pack: 规则的属于方，如果没有指定pack则为default
description: 规则的描述
enabled: 规则是否开启(true或者false)
trigger:emitted from sensors to monitor, and optionally parameters associated with that trigger.
criteria:可选择的集合，包含
一个trigger的payload的属性
criteria比较的类型
pattern: to match against.
action:当一个规则被满足时，执行的动作，包含:
ref:动作或工作流的名称
parameters: 执行动作的参数(可选)
管理规则
通过命令
st2 rule create ${PATH_TO_RULE}
来部署规则
例如:
st2 rule create /usr/share/doc/st2/examples/rules/sample_rule_with_webhook.yaml
加载所有规则，使用:
st2ctl reload --register-rules
自定义规则被放在:
/opt/stackstorm/packs/<pack_name>/rules
目录。
例如:
/opt/stackstorm/packs/examples/rules
2 编写一个规则文件
print_rule.yaml
内容如下:
--------------------------------------------------------------------------------
name: "print_rule"
pack: "default"
description: "print rule"
enabled: true
trigger:
type: "core.st2.CronTimer"
parameters:
timezone: "Asia/Shanghai"
day_of_week: ""hour: ""
minute: "*"
second: 0
action:
ref: "default.write_content_action"
parameters:
content: "first_rule"
注意:
这里action下面的ref一定是实际的action名称，
不要写错成action执行的脚本文件名
将规则文件放在对应目录下面
关键是规则存放在哪里，
最终存放在:
/opt/stackstorm/packs/default/rules
3 创建规则
st2 rule create /opt/stackstorm/packs/default/rules/write_rule.yaml
输出结果:
+---------------+----------------------------------------------------------+
| Property | Value |
+---------------+----------------------------------------------------------+
| id | 5c6559a59dc6d60729fc00ad |
| name | rule_write_content |
| pack | default |
| description | write content rule |
| action | { |
| | "ref": "default.write_content.sh", |
| | "parameters": { |
| | "content": "chaos_first_rule" |
| | } |
| | } |
| context | { |
| | "user": "st2admin" |
| | } |
| criteria | |
| enabled | True |
| metadata_file | |
| ref | default.rule_write_content |
| tags | |
| trigger | { |
| | "type": "core.st2.CronTimer", |
| | "ref": "core.51b8a980-8c60-4898-baba-5c10c332e80c", |
| | "parameters": { |
| | "timezone": "Asia/Shanghai", |
| | "second": 0, |
| | "minute": "", || | "hour": "", |
| | "day_of_week": "*" |
| | } |
| | } |
| type | { |
| | "ref": "standard", |
| | "parameters": {} |
| | } |
| uid | rule:default:rule_write_content |
+---------------+----------------------------------------------------------+
4 创建规则中指定的动作
4.1 先定义action的metadata文件
具体是创建一个文件名字为:
write_content_metadata.yaml
具体内容如下:
name: "write_content_action"
description: "write content"
runner_type: "python-script"
enabled: true
entry_point: "write_content.py"
parameters:
content:
type: "string"
description: "content parameter"
required: true
position: 0
4.2 创建action对应的脚本文件
文件名字如下: write_content.py
具体内容如下:
from datetime import datetime
from st2common.runners.base_action import Action
class CounterAction(Action):
# append content into file
def run(self, content):
fileName = "/home/counter.txt"
try:
currTime = str(datetime.now())
# note, a+ means append instead of w+
with open(fileName, "a+") as fr:
realContent = "content: " + str(content) + ", time: " + currTime + "\n"
fr.write(realContent)
return (True, content)
except Exception as ex:
return (False, content)
4.3 将action脚本文件write_content.py拷贝到目录
/opt/stackstorm/packs/default/actions
4.4 创建action
执行如下命令: st2 action create write_content_metadata.yaml
创建动作后的输出结果:
+---------------+--------------------------------------------+
| Property | Value |
+---------------+--------------------------------------------+
| id | 5c655abf9dc6d60729fc00ae |
| name | write_content_action |
| pack | default |
| description | write content |
| enabled | True |
| entry_point | write_content.py |
| metadata_file | |
| notify | |
| output_schema | |
| parameters | { |
| | "content": { |
| | "position": 0, |
| | "required": true, |
| | "type": "string", |
| | "description": "content parameter" |
| | } |
| | } |
| ref | default.write_content_action |
| runner_type | python-script |
| tags | |
| uid | action:default:write_content_action |
+---------------+--------------------------------------------+
5 检测定时器是否生效
根据步骤4.2中会生成/home/counter.txt，如果看到该文件，并且文件内容类似如下:
content: first_rule, time: 2018-02-04 22:26:22.712110
说明定时器生效。
6 总结
编写规则的完整过程
1 编写规则，主要包含两部分:
触发器和动作。
动作需要提供:动作元数据文件用于动作注册，还需要提供具体执行的动作脚本，将该动作执行脚本放到/opt/stackstorm/packs/<pack_name>/actions目录下。
先注册动作，然后可以执行: st2 action <action_name> 来手动先验证一下动作本身是否正确
然后注册规则。
然后可以打开: /var/log/st2rulesengine.log，查看规则校验结果，如果校验成功，
然后打开: /var/log/st2actionrunner.<xxx>.log 查看动作具体执行情况。
