【AWS】AWS Step Functions with Lambda

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【AWS】AWS Step Functions with…

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2024.08.12

【AWS】AWS Step Functions with Lambda

概要
AWSアカウントにサインアップ
Lambdaを作成
ASL(Amazon States Language)
処理（ステップ）の流れ
全体のASL
実行
備考
参考

【AWS】AWS Step Functionsを触ってみる

1. 概要

前回は「AWS Step Functions」を触ってみる内容でした。今回は「AWS Step Functions」で「Lambda」を扱う内容となります。

2-1. 前提条件

こちらを参考
- 【AWS】AWSアカウントを作成し、マネジメントコンソールにサインインする – 株式会社isub

3. Lambdaを作成

3-1. こちらを参考

【AWS】Lambdaを使ってみる – 株式会社isub
ソースコード

export const handler = async (event, context) => {
  
  const length = event.length;
  const width = event.width;
  let area = calculateArea(length, width);
  console.log(`The area is ${area}`);
        
  console.log('CloudWatch log group: ', context.logGroupName);
  
  let data = {
    "area": area,
  };
  return data;

  function calculateArea(length, width) {
    return length * width;
  }
};

4. ASL(Amazon States Language)

4-1. こちらを参考

【AWS】AWS Step Functionsを触ってみる – 株式会社isub

5. 処理（ステート）の流れ

5-1. 全体のフロー

5-2. States

5-2-1. Pass

    "Getting started": {
      "Type": "Pass",
      "Parameters": {
        "length.$": "$.length",
        "width.$": "$.width"
      },
      "Next": "Lambda Invoke"
    },

実行時にパラメータを受け取って、次に渡す。
- length
- width
パラメータ名と値の変数に注意

5-2-2. Lambda Invoke

    "Lambda Invoke": {
      "Type": "Task",
      "Resource": "arn:aws:states:::lambda:invoke",
      "OutputPath": "$.Payload",
      "Parameters": {
        "Payload.$": "$",
        "FunctionName": "arn:aws:lambda:ap-northeast-1:123456789012:function:myLambdaFunction:$LATEST"
      },
      "Retry": [
        {
          "ErrorEquals": [
            "Lambda.ServiceException",
            "Lambda.AWSLambdaException",
            "Lambda.SdkClientException",
            "Lambda.TooManyRequestsException"
          ],
          "IntervalSeconds": 1,
          "MaxAttempts": 3,
          "BackoffRate": 2
        }
      ],
      "Next": "Over 100?"
    },

実行Lambdaを指定
OutputPath
- 次のステート（Over 100?）にLambdaの計算結果を渡す

5-2-3. Over 100?

    "Over 100?": {
      "Type": "Choice",
      "Choices": [
        {
          "Variable": "$.area",
          "NumericLessThan": 100,
          "Next": "Failure"
        },
        {
          "Variable": "$.area",
          "NumericGreaterThanEquals": 100,
          "Next": "Yes"
        }
      ]
    },

入力（area）が
- 100未満：Failureへ進む
- 100以上：Yesへ進む

5-2-4-1-1. Failure

    "Failure": {
      "Type": "Fail"
    },

5-2-4-2-1. Yes

    "Yes": {
      "Type": "Pass",
      "Next": "Wait 3 seconds"
    },

次のステート（Wait 3 sec）に進む

5-2-4-2-2. Wait 3 sec

    "Wait 3 seconds": {
      "Type": "Wait",
      "Seconds": 3,
      "Next": "Success"
    },

3秒Wait後、次のステート（Success）へ進む

5-2-4-2-3. Success

    "Success": {
      "Type": "Succeed"
    }

6. 全体のASL

{
  "Comment": "My state machine with Lambda.",
  "StartAt": "Getting started",
  "States": {
    "Getting started": {
      "Type": "Pass",
      "Parameters": {
        "length.$": "$.length",
        "width.$": "$.width"
      },
      "Next": "Lambda Invoke"
    },
    "Lambda Invoke": {
      "Type": "Task",
      "Resource": "arn:aws:states:::lambda:invoke",
      "OutputPath": "$.Payload",
      "Parameters": {
        "Payload.$": "$",
        "FunctionName": "arn:aws:lambda:ap-northeast-1:123456789012:function:myLambdaFunction:$LATEST"
      },
      "Retry": [
        {
          "ErrorEquals": [
            "Lambda.ServiceException",
            "Lambda.AWSLambdaException",
            "Lambda.SdkClientException",
            "Lambda.TooManyRequestsException"
          ],
          "IntervalSeconds": 1,
          "MaxAttempts": 3,
          "BackoffRate": 2
        }
      ],
      "Next": "Over 100?"
    },
    "Over 100?": {
      "Type": "Choice",
      "Choices": [
        {
          "Variable": "$.area",
          "NumericLessThan": 100,
          "Next": "Failure"
        },
        {
          "Variable": "$.area",
          "NumericGreaterThanEquals": 100,
          "Next": "Yes"
        }
      ]
    },
    "Failure": {
      "Type": "Fail"
    },
    "Yes": {
      "Type": "Pass",
      "Next": "Wait 3 seconds"
    },
    "Wait 3 seconds": {
      "Type": "Wait",
      "Seconds": 3,
      "Next": "Success"
    },
    "Success": {
      "Type": "Succeed"
    }
  }
}