aws(学习笔记第三十六课) apigw-http-api-lambda-dynamodb

aws(学习笔记第三十六课) apigw-http-api-lambda-dynamodb

• 使用api gateway中使用lambda+dynamodb

学习内容：

• 使用api gateway
• 使用lambda
• 使用dynamodb

1. 整体架构

1.1 代码链接

• 代码链接（apigw-http-api-lambda-dynamodb-python-cdk）
• aws(学习笔记第十四课) 面向NoSQL DB的DynamoDB
  可以复习下以前的dynamodb的知识。

1.2 整体架构

• API gateway访问lambda函数
• lambda通过终端节点访问dynamodb

2. 代码解析

2.1 创建vpc

# VPC
        vpc = ec2.Vpc(
            self,
            "Ingress",
            cidr="10.1.0.0/16",
            subnet_configuration=[
                ec2.SubnetConfiguration(
                    name="Private-Subnet", subnet_type=ec2.SubnetType.PRIVATE_ISOLATED,
                    cidr_mask=24
                )
            ],
        )

这里，只创建private subnet。

2.2 创建vpc的终端节点

通常，private subnet里面的lambda是没有办法访问dynamodb的，如果想访问。有两种方式：

• 一种是通过给public subnet里面设定NAT gateway。
• 另一种通过vpc endpoint，即vpc的终端节点。终端节点需要执行面向的service，这里是dynamodb。

 # Create VPC endpoint
        dynamo_db_endpoint = ec2.GatewayVpcEndpoint(
            self,
            "DynamoDBVpce",
            service=ec2.GatewayVpcEndpointAwsService.DYNAMODB,
            vpc=vpc,
        )

2.3 对vpc的终端节点设定policy

# This allows to customize the endpoint policy
        dynamo_db_endpoint.add_to_policy(
            iam.PolicyStatement(  # Restrict to listing and describing tables
                principals=[iam.AnyPrincipal()],
                actions=[                "dynamodb:DescribeStream",
                "dynamodb:DescribeTable",
                "dynamodb:Get*",
                "dynamodb:Query",
                "dynamodb:Scan",
                "dynamodb:CreateTable",
                "dynamodb:Delete*",
                "dynamodb:Update*",
                "dynamodb:PutItem"],
                resources=["*"],
            )
        )

这里设定通过该endpoint，任何resource都能够进行dynamodb相关的操作。

2.4 创建dynamodb的``table

        # Create DynamoDb Table
        demo_table = dynamodb_.Table(
            self,
            TABLE_NAME,
            partition_key=dynamodb_.Attribute(
                name="id", type=dynamodb_.AttributeType.STRING
            ),
        )

2.5 创建lambda函数

        # Create the Lambda function to receive the request
        api_hanlder = lambda_.Function(
            self,
            "ApiHandler",
            function_name="apigw_handler",
            runtime=lambda_.Runtime.PYTHON_3_9,
            code=lambda_.Code.from_asset("lambda/apigw-handler"),
            handler="index.handler",
            vpc=vpc,
            vpc_subnets=ec2.SubnetSelection(
                subnet_type=ec2.SubnetType.PRIVATE_ISOLATED
            ),
            memory_size=1024,
            timeout=Duration.minutes(5),
        )

2.6 lambda函数的代码（/lambda/apigw-handler/）

def handler(event, context):
    table = os.environ.get("TABLE_NAME")
    logging.info(f"## Loaded table name from environemt variable DDB_TABLE: {table}")
    if event["body"]:
        item = json.loads(event["body"])
        logging.info(f"## Received payload: {item}")
        year = str(item["year"])
        title = str(item["title"])
        id = str(item["id"])
        dynamodb_client.put_item(
            TableName=table,
            Item={"year": {"N": year}, "title": {"S": title}, "id": {"S": id}},
        )
        message = "Successfully inserted data!"
        return {
            "statusCode": 200,
            "headers": {"Content-Type": "application/json"},
            "body": json.dumps({"message": message}),
        }
    else:
        logging.info("## Received request without a payload")
        dynamodb_client.put_item(
            TableName=table,
            Item={
                "year": {"N": "2012"},
                "title": {"S": "The Amazing Spider-Man 2"},
                "id": {"S": str(uuid.uuid4())},
            },
        )
        message = "Successfully inserted data!"
        return {
            "statusCode": 200,
            "headers": {"Content-Type": "application/json"},
            "body": json.dumps({"message": message}),
        }

2.7 为dynamodb的table设定lambda函数的权限，以及通过env设定表名

        # grant permission to lambda to write to demo table
        demo_table.grant_write_data(api_hanlder)
        api_hanlder.add_environment("TABLE_NAME", demo_table.table_name)

2.8 创建api gateway，并设定handler为lambda函数

        # Create API Gateway
        apigw_.LambdaRestApi(
            self,
            "Endpoint",
            handler=api_hanlder,
        )

3 执行整个架构

3.1 开始部署

cdk --require-approval never deploy

3.2 访问API gateway