サーバーレスにおけるべき等性の実装 (バッチ処理と分散トランザクション編) ~ サーバーレスが気になる開発者に捧ぐ「べき等性」ことはじめ 第 4 回

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  idempotency-app
  Sample SAM Template for idempotency-app

Globals:
  Function:
    Timeout: 5
    Tracing: Active
    Environment:
      Variables:
        POWERTOOLS_METRICS_NAMESPACE: "idempotency-app"
        POWERTOOLS_SERVICE_NAME: "order-app"
  Api:
    TracingEnabled: true

Resources:
  Orders:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: Orders
      AttributeDefinitions:
        - AttributeName: order_id
          AttributeType: S
      KeySchema:
        - AttributeName: order_id
          KeyType: HASH
      BillingMode: PAY_PER_REQUEST

  IdempotencyTable:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: IdempotencyTable
      AttributeDefinitions:
        - AttributeName: id
          AttributeType: S
      KeySchema:
        - AttributeName: id
          KeyType: HASH
      TimeToLiveSpecification:
        AttributeName: expiration
        Enabled: true
      BillingMode: PAY_PER_REQUEST

  IdempotencyFunction:
    Type: AWS::Serverless::Function 
    Properties:
      CodeUri: src/
      Handler: app.lambda_handler
      Runtime: python3.8
      Events:
        OrderApi:
          Type: Api 
          Properties:
            Path: /orders
            Method: post
      Environment:
        Variables:
          TABLE_NAME: !Ref Orders
          LOG_LEVEL: INFO
      Policies:
        - DynamoDBCrudPolicy:
            TableName: !Ref Orders
        - DynamoDBCrudPolicy:
            TableName: !Ref IdempotencyTable

import json
import os
import boto3
import botocore
from aws_lambda_powertools.utilities.idempotency import (
    IdempotencyConfig, DynamoDBPersistenceLayer, idempotent)

persistency_layer = DynamoDBPersistenceLayer(table_name='IdempotencyTable')
config = IdempotencyConfig(event_key_jmespath='body', expires_after_seconds=10*60)

dynamodb = boto3.resource('dynamodb')
tableName = os.getenv('TABLE_NAME', 'Orders')

@idempotent(config=config, persistence_store=persistency_layer)
def lambda_handler(event, context):

    body_text = event['body']
    logger.info("body_text: " + body_text)

    body = json.loads(body_text)
    order_id = body['order_id']
    customer_id = body['customer_id']
    order_count = body['order_count']

    logger.info({
        "order_id": order_id,
        "customer_id": customer_id,
        "count": order_count
    })

    response = create_order(dynamodb, tableName, order_id, customer_id, order_count)
 
    return {
        "statusCode": 200,
        "body": json.dumps({
            "order_id": order_id,
            "message": "oder created.",
        }),
    }


def create_order(dynamodb, tableName, order_id, customer_id, order_count):
    
    ...以下省略