StackStorm分析（八）Rule說明

StackStorm介紹

       StackStorm是一個強大的自動化平臺，結合DevOps和ChatOps，提供可擴展、靈活和健壯的工具鏈用於應用、服務和工作流的自動化能力。

 

 

Rule

       Rule是映射Trigger到Action（或者Workflow），即當事件觸發後，通過Rule定義的標準（Criteria）進行匹配，當匹配成功將執行Action（或者Workflow）。

 

Rule的定義格式：

---

    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的名稱
• pack: Rule歸屬的Pack
• enabled: Rule的啓用開關
• trigger: 配置Trigger的類型和參數
• criteria：Rule的匹配規則，當 Trigger的參數滿足的條件觸發Action
• action: Rule匹配需要執行的Action配置

 

我們可以通過命令行創建Rule

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

 

查詢Rule

$ st2 rule list

$ st2 rule get examples.sample_rule_with_webhook

 

Criteria

Rule的Criteria 提供了一系列方法，可以設置各種匹配規則：

• 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.

測試

StackStorm提供一個工具st2-rule-tester可以用於快速測試Rule。

 

首先創建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"

         這個Rule是匹配Trigger(irc.pubmsg)的參數message是否含有字符串StackStorm（不區分大小寫），匹配後執行Action(slack.post_message)。

 

然後創建用於測試的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"

 

執行測試

Trigger Instace 1匹配Rule並執行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 ===

另外也可以根據實際的Trigger Instance去測試：

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

 

參考

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

作者簡介

吳龍輝，現任網宿科技雲計算架構師，致力於雲計算PaaS的研究和實踐，《Kubernetes實戰》作者，活躍於CloudFoundry，Docker，Kubernetes等開源社區，貢獻代碼和撰寫技術文檔。 
郵箱：[email protected]