AWS SNS，向 slack 发送“连续”通知

Question

在高层次上，我写了一个 lambda，它在有错误或没有错误时通知 slack。

从 aws 工具链的角度来看，技术设计如下所示：

验收标准（BDD 风格）

 Scenario: As an engineer I want to get notified if my lambda PASSED or FAILED whenever it executes
    Given I have a lambda function that runs on a schedule (9am everyday)
    Given I have a metric filter that looks for the string "error" in the logs
      And I created an alarm that does the following:
  # +------------------------+--------------+
  # |         ALARM                         |
  # +------------------------+--------------+
  # | Statistic              | Sum          |
  # | Period                 | 5 minutes    |
  # | Threshold type         | Static       |
  # | Alarm condition        | >= threshold |
  # | Threshold value        | 1            |
  # | Datapoints to Alarm    | 1 of 1       |
  # | missing data treatment | ignore       |
  # | Alarm State            | in Alarm     |
  # +------------------------+--------------+
      And I created another alarm that does the following:
  # +------------------------+--------------+
  # |           OK                          |
  # +------------------------+--------------+
  # | Statistic              | Sum          |
  # | Period                 | 5 minutes    |
  # | Threshold type         | Static       |
  # | Alarm condition        | <= threshold |
  # | Threshold value        | 1            |
  # | Datapoints to Alarm    | 1 of 1       |
  # | missing data treatment | good         |
  # | Alarm State            | OK           |
  # +------------------------+--------------+
     Then EVERY TIME time my function executes without "error" Then I should get "OK" 
     Then EVERY TIME time my function executes with "error" then I should get "ALARM"

实际行为是它只会发送一次通知，并且只会在警报类型更改时再次发送，即

  ALARM -> OK
  OK -> ALARM

我似乎没有收到有关此模式的通知

  ALARM -> ALRM
  OK -> OK

理想情况下，我希望每次 function 执行时都会收到通知

Answer 1

无需使用 CloudWatch 警报。 如果每次 Lambda 执行时都需要一条消息，您应该将 SNS 消息作为 Lambda function 中的最后一件事发布。

try {

    // existing code goes here...

    snsClient.publish("my-chatbot-topic", "Some success message");
} catch (Exception e) {
    snsClient.publish("my-chatbot-topic", "Some error message");
    // rethrow the exception so that the lambda still fails for this
    throw e;
}

Answer 2

根据AWS 文档：

警报仅针对持续的 state 更改调用操作。 CloudWatch 警报不会仅仅因为它们位于特定的 state 中而调用操作，state 必须已更改并保持指定数量的周期。

一种解决方案是将 stream CW 记录到发送 SNS 消息的 lambda function 中。 通过快速搜索，我发现了这个代码（我自己没有尝试过）： https://github.com/codemonauts/aws-cloudwatch-stream-filter-sns-gateway