StackStorm分析（八）Rule说明

StackStorm介绍

       StackStorm是一个强大的自动化平台，结合DevOps和ChatOps，提供可扩展、灵活和健壮的工具链用于应用、服务和工作流的自动化能力。

 

 

Rule

       Rule是映射Trigger到Action（或者Workflow），即当事件触发后，通过Rule定义的标准（Criteria）进行匹配，当匹配成功将执行Action（或者Workflow）。

Rule的定义格式：

---     name: "rule_name"                      # required     pack: "examples"                       # optional     description: "Rule description."       # optional     enabled: true                          # required     trigger:                               # required         type: "trigger_type_ref"     criteria:                              # optional         trigger.payload_parameter_name1:             type: "regex"            pattern : "^value$"         trigger.payload_parameter_name2:             type: "iequals"             pattern : "watchevent"     action:                                # required         ref: "action_ref"         parameters:                        # optional             foo: "bar"             baz: "{{ trigger.payload_parameter_1 }}"

• name: Rule的名称
• pack: Rule归属的Pack
• enabled: Rule的启用开关
• trigger: 配置Trigger的类型和参数
• criteria：Rule的匹配规则，当 Trigger的参数满足的条件触发Action
• action: Rule匹配需要执行的Action配置

我们可以通过命令行创建Rule

$ st2 rule create /usr/share/doc/st2/examples/rules/sample_rule_with_webhook.yaml

查询Rule

$ st2 rule list $ st2 rule get examples.sample_rule_with_webhook

Criteria

Rule的Criteria 提供了一系列方法，可以设置各种匹配规则：

• equals Values are equal (for values of arbitrary type).
• nequals Values are not equal (for values of arbitrary type).
• lessthan Trigger value is less than the provided value.
• greaterthan Trigger value is greater than the provided value.
• matchwildcard Trigger value matches the provided wildcard-like string. This operator provides support for Unix shell-style wildcards which means you can use characters such as * and ?. This operator is preferred over regex for simple string matches.
• regex Trigger value matches the provided regular expression pattern. This operator behaves like re.search('pattern', trigger_value).
• iregex Trigger value matches the provided regular expression pattern case insensitively. This operator behaves like re.search('pattern', trigger_value, re.IGNORECASE).
• matchregex Trigger value matches the provided regular expression pattern. This operator is deprecated in favor of regex and iregex
• iequals String trigger value equals the provided value case insensitively.
• contains Trigger value contains the provided value. Keep in mind that the trigger value can be either a string or an array (list).
• ncontains Trigger value does not contain the provided value. Keep in mind that the trigger value can be either a string or an array (list).
• icontains String trigger value contains the provided value case insensitively.
• incontains String trigger value does not contain the provided string value case insensitively.
• startswith Beginning of the string trigger value matches the provided string value.
• istartswith Beginning of the string trigger value matches the provided string value case insensitively.
• endswith End of the string trigger value matches the provided string value.
• iendswith End of the string trigger value matches the provided string value case insensitively.
• timediff_lt Time difference between trigger value and current time is less than the provided value.
• timediff_gt Time difference between trigger value and current time is greater than the provided value.
• exists Key exists in payload.
• nexists Key doesn't exist in payload.
• inside Trigger payload is inside provided value. (e.g. testing if "trigger.payload in provided_value"). Reverse of contains. (where contains would test for "trigger.payload contains provided_value").
• ninside Trigger payload is not inside provided value. (e.g. testing if "trigger.payload not in provided_value"). Reverse of ncontains (where contains would test for "trigger.payload does not contain provided_value").
• search Search an array (list) in the trigger payload that matches child criteria. See the Advanced Comparison section for more information and examples.

测试

StackStorm提供一个工具st2-rule-tester可以用于快速测试Rule。

首先创建Rule：

st2-rule-tester

---  name: "relayed_matched_irc_message"  pack: "irc"  description: "Relay IRC message to Slack if the message contains word StackStorm"  enabled: true  trigger:     type: "irc.pubmsg"     parameters: {}  criteria:       trigger.message:           type: "icontains"           pattern: "StackStorm"  action:     ref: "slack.post_message"     parameters:         message: "{{ trigger.source.nick }} on {{ trigger.channel }}: {{ trigger.message }}"         channel: "#irc-relay"

         这个Rule是匹配Trigger(irc.pubmsg)的参数message是否含有字符串StackStorm（不区分大小写），匹配后执行Action(slack.post_message)。

然后创建用于测试的Trigger Instance：

trigger_instance_1.yaml： message包含字符串StackStorm，匹配Rule

---     trigger: "irc.pubmsg"     payload:       source:           nick: "Kami_"           host: "gateway/web/irccloud.com/x-uvv"       channel: "#stackstorm"       timestamp: 1419166748,       message: "stackstorm is cool!"

trigger_instance_2.yaml:不匹配Rule

---     trigger: "irc.pubmsg"     payload:       source:           nick: "Kami_"           host: "gateway/web/irccloud.com/x-uvv"       channel: "#stackstorm"       timestamp: 1419166748,       message: "blah blah"

执行测试

Trigger Instace 1匹配Rule并执行Action

$ st2-rule-tester --rule=./my_rule.yaml --trigger-instance=./trigger_instance_1.yaml --config-file=/etc/st2/st2.conf 2018-05-17 06:44:17,972 INFO [-] Connecting to database "st2" @ "mongo:27017" as user "None". 2018-05-17 06:44:18,144 INFO [-] Validating rule irc.relayed_matched_irc_message for pubmsg. 2018-05-17 06:44:18,169 INFO [-] 1 rule(s) found to enforce for pubmsg. 2018-05-17 06:44:18,170 INFO [-] Failed to retrieve config for pack <Mock name='mock.pack' id='140111251335056'> and user stanley: 'Mock' object is not iterable 2018-05-17 06:44:18,173 INFO [-] Action parameters resolved to: 2018-05-17 06:44:18,173 INFO [-]    message: Kami_ on #stackstorm: stackstorm is cool! 2018-05-17 06:44:18,174 INFO [-]    channel: #irc-relay 2018-05-17 06:44:18,174 INFO [-] === RULE MATCHES ===

Trigger Instace 2不匹配Rule

$ st2-rule-tester --rule=./my_rule.yaml --trigger-instance=./trigger_instance_2.yaml --config-file=/etc/st2/st2.conf 2018-05-17 06:47:27,426 INFO [-] Connecting to database "st2" @ "mongo:27017" as user "None". 2018-05-17 06:47:27,605 INFO [-] Validating rule irc.relayed_matched_irc_message for pubmsg. 2018-05-17 06:47:27,627 INFO [-] Validation for rule irc.relayed_matched_irc_message failed on criteria -   key: trigger.message   pattern: StackStorm   type: icontains   payload: blah blah 2018-05-17 06:47:27,627 INFO [-] 0 rule(s) found to enforce for pubmsg. 2018-05-17 06:47:27,628 INFO [-] === RULE DOES NOT MATCH ===

另外也可以根据实际的Trigger Instance去测试：

$ st2-rule-tester --rule-ref=my_pack.fire_on_execution --trigger-instance-id=566b4be632ed352a09cd347d --config-file=/etc/st2/st2.conf

参考

• https://github.com/StackStorm/st2docs/blob/master/docs/source/rules.rst

作者简介

吴龙辉，现任网宿科技云计算架构师，致力于云计算PaaS的研究和实践，《Kubernetes实战》作者，活跃于CloudFoundry，Docker，Kubernetes等开源社区，贡献代码和撰写技术文档。 
邮箱： [email protected]