aws(学习笔记第四十二课) serverless-backend
- 使用Amazon API Gateway以及lamda进行后台处理
学习内容：
- 使用Amazon API Gateway
- 使用lambda处理API Gateway哀求，接受json参数
- 使用Amazon S3 - Bucket to store images or files
- 使用Amazon DynamoDB
- 使用Amazon Cognito进行用户认证
1. 整体架构
1.1 代码链接
代码毗连(serverless-backend)
1.2 整体架构
2 代码分析
2.1 创建S3 bucket
- bucket_name = _cfnParameter(self, "uploadBucketName", type="String",
- description="The name of the Amazon S3 bucket where uploaded images will be stored.")
- my_bucket = _s3.Bucket(self, id='s3bucket',
- bucket_name=bucket_name.value_as_string)
- my_bucket.grant_read_write(my_lambda)
- cdk --require-approval never deploy ServerlessBackendStack --parameters uploadBucketName=finlay-20250524-upload
2.2 创建cognito user pool
- user_pool = _cognito.UserPool(self, "UserPool")
- user_pool.add_client("app-client", auth_flows=_cognito.AuthFlow(
- user_password=True
- ),
- supported_identity_providers=[
- _cognito.UserPoolClientIdentityProvider.COGNITO]
- )
- auth = _apigateway.CognitoUserPoolsAuthorizer(self, "imagesAuthorizer",
- cognito_user_pools=[
- user_pool]
- )
2.3 创建dynamoDB
- my_table = _dynamodb.Table(self, id='dynamoTable', table_name='formmetadata', partition_key=_dynamodb.Attribute(
- name='userid', type=_dynamodb.AttributeType.STRING)) #change primary key here
2.4 创建S3 bucket
- my_bucket = _s3.Bucket(self, id='s3bucket',
- bucket_name=bucket_name.value_as_string)
使用S3 bucket来进行生存图片，这里S3 bucket的名字是通过cdk deploy执行时候，指定的参数uploadBucketName。
2.5 创建lambda，并赋予权限
- my_lambda = _lambda.Function(self, id='lambdafunction', function_name="formlambda", runtime=_lambda.Runtime.PYTHON_3_9,
- handler='index.handler',
- code=_lambda.Code.from_asset(
- os.path.join("./", "lambda-handler")),
- environment={
- 'bucket': my_bucket.bucket_name,
- 'table': my_table.table_name
- }
- )
- my_bucket.grant_read_write(my_lambda)
- my_table.grant_read_write_data(my_lambda)
- 生存image文件的meta data
- 生存image文件到S3 bucket
下面是lambda的处理代码。
- def upload_metadata(key, userid):
- table = os.environ['table']
- bucket = os.environ['bucket']
- reference = {'Bucket': {'S': bucket}, 'Key': {'S': key}}
- response = dynamodb.put_item(
- TableName=table,
- Item={"userid": {
- 'S': userid}, "photo_reference": {'M': reference}})
- print(response)
- def upload_image(image_id, img, userid):
- bucket = os.environ['bucket']
- extension = imghdr.what(None, h=img)
- key = f"{image_id}.{extension}"
- try:
- s3.put_object(Bucket=bucket, Key=key, Body=img)
- upload_metadata(key, userid)
- except botocore.exceptions.ClientError as e:
- print(e)
- return False
- return True
- def handler(event, context):
- print(event)
- # Generate random image id
- image_id = str(uuid.uuid4())
- data = json.loads(event['body'])
- userid = data['userid']
- img = base64.b64decode(data['photo'])
- if upload_image(image_id, img, userid):
- return {
- 'statusCode': 200,
- 'headers': {
- 'Access-Control-Allow-Headers': '*',
- 'Access-Control-Allow-Origin': '*',
- 'Access-Control-Allow-Methods': 'OPTIONS,POST,GET'
- },
- 'body': json.dumps('Success!')
- }
- return {
- 'statusCode': 500,
- 'headers': {
- 'Access-Control-Allow-Headers': '*',
- 'Access-Control-Allow-Origin': '*',
- 'Access-Control-Allow-Methods': 'OPTIONS,POST,GET'
- },
- 'body': json.dumps('Request Failed!')
- }
- my_api = _apigateway.LambdaRestApi(
- self, id='lambdaapi', rest_api_name='formapi', handler=my_lambda, proxy=True)
- postData = my_api.root.add_resource("form")
- postData.add_method("POST", authorizer=auth,
- authorization_type=_apigateway.AuthorizationType.COGNITO) # POST images/files & metadata
- 指定lambda函数作为处理http post哀求的handler
- 指定认证方式为cognito的user pool
3. 执行cdk
3.1 查抄S3 bucket和dynamoDB
如果同样名字的S3 bucket和dynamoDB已经存在，那么Stack执行会失败，所以提前查抄。
3.2 开始执行Stack
3.2.1 修改lambda执行环境的代码
- my_lambda = _lambda.Function(self, id='lambdafunction', function_name="formlambda", runtime=_lambda.Runtime.PYTHON_3_9,
- handler='index.handler',
- code=_lambda.Code.from_asset(
- os.path.join("./", "lambda-handler")),
- environment={
- 'bucket': my_bucket.bucket_name,
- 'table': my_table.table_name
- }
- )
3.2.2 开始执行
- cd serverless-backend
- python -m venv .venv
- source .venv/Script/activate
- pip install -r requirement.txt
- cdk --require-approval never deploy ServerlessBackendStack --parameters uploadBucketName=finlay-20250524-upload
到这里，摆设乐成。
4 测试步伐
4.1 Create Cognito User
之后进入cognito的user配置画面
创建用户，使用user name和password和user pool ID
- 之后使用aws cli，设定用户和暗码为permanent。这里，用户名字为finlay，暗码自己设定。这里带有XXX都是需要替换的。
- aws cognito-idp admin-set-user-password --user-pool-id ap-northeast-1-XXXXXX --username finlayXXXX --password XXXXXX --permanent
- 之后取得finlay这个user的id token
- aws cognito-idp initiate-auth --region ap-northeast-1 --auth-flow USER_PASSWORD_AUTH --client-id XXXXXX --auth-parameters USERNAME=finlay,PASSWORD=XXXXXX
之后生存IdToken随后使用。
4.2 得到API Gateway的调用url
4.3 将图片文件进行base64的encode
- import base64
- with open(r"d:\test.jpg", "rb") as image_file:
- base64_string = base64.b64encode(image_file.read()).decode('utf-8')
- print(base64_string)
4.4 使用Postman进行post
4.4.1 设定认证谍报Authorization
- URL设定
URL这里设定成前面取得的API Gateway的url，注意，后缀加上form。
https://XXXXXX.execute-api.ap-northeast-1.amazonaws.com/prod/form
- Authentication设定
这里设定成前面取得的idToken。
4.4.2 设定json
设定形式为
- { "userid": "myUserID", "photo": "image details" }
方法选择post，之后选择send
最后会显示乐成success。
4.4.4 从S3 bucket中取得生存图片
5 注意扫除Stack
- 扫除Stack
- 扫除S3 bucket
- 扫除dynamoDB
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