Come posso correggere la dipendenza circolare tra un'autorizzazione AWS Lambda e le risorse del gruppo target in AWS CloudFormation?
Voglio correggere la dipendenza circolare tra un'autorizzazione AWS Lambda (AWS::Lambda::Permission) e le risorse del gruppo target (AWS::ElasticLoadBalancingV2::TargetGroup) in AWS CloudFormation.
Breve descrizione
Ottieni una dipendenza circolare se fornisci AWS::Lambda::Permission ad AWS::ElasticLoadBalancingV2::TargetGroup invece di LoadBalancer per limitare l'accesso alla tua funzione Lambda. Questo perché l'autorizzazione Lambda deve esistere prima di associare la funzione Lambda al gruppo target che si vuole creare. Quando crei l'autorizzazione Lambda, devi associarla a un Principal e SourceARN AWS (in questo caso, un gruppo target). Ecco perché il gruppo target deve esistere prima di creare l'autorizzazione Lambda. Per correggere questa dipendenza circolare, puoi utilizzare una risorsa personalizzata supportata da Lambda.
Soluzione
1. Crea un file denominato index.py che include quanto segue:
Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. def handler(event, context): return { "statusCode": 200, "statusDescription": "HTTP OK", "isBase64Encoded": False, "headers": { "Content-Type": "text/html" }, "body": "<h1>Hello from Lambda!</h1>" }
Nota: La funzione AWS Lambda in index.py visualizza una pagina HTML con il messaggio "Hello from Lambda!" quando viene richiamata la funzione.
2. Aggiungi il file index.py a un file di archivio denominato website.zip.
3. Per creare un file.zip di index.py, esegui il seguente comando:
$zip website.zip index.py
4. Crea un file chiamato cfnresponse.py basato sul modello AWS CloudFormation su AWS GitHub.
5. Crea un file riempito chiamato custom.py in base a quanto segue:
Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. import logging import boto3, json, botocore import cfnresponse #Define logging properties for 'logging' log = logging.getLogger() log.setLevel(logging.INFO) #Main Lambda function to be executed def lambda_handler(event, context): try: if event['RequestType'] == "Create" or event['RequestType'] == "Update": # print the event type sent from cloudformation log.info ("'" + str(event['RequestType']) + "' event was sent from CFN") # Imput Parameters TargetGroupARN = event['ResourceProperties']['TargetGroupARN'] LambdaFunctionARN = event['ResourceProperties']['LambdaFunctionARN'] log.info("TargetGroup ARN value is:" + TargetGroupARN) log.info("Lambda Function ARN value is:" + LambdaFunctionARN) responseData = {} # ELBV2 initilize client = boto3.client('elbv2') # Initilize Vars response = '' error_msg = '' # Make the 1st API call to get the Lambda policy and extract SID of the initial permissions that were created by the CFN template. try: response = client.register_targets( TargetGroupArn=TargetGroupARN, Targets=[ { 'Id': LambdaFunctionARN }, ] ) except botocore.exceptions.ClientError as e: error_msg = str(e) if error_msg: log.info("Error Occured:" + error_msg) response_msg = error_msg # TODO: SIGNAL BACK TO CLOUDFORMATION log.info("Trying to signal FAILURE back to cloudformation.") responseData = {"Message" : response_msg, "Function" : context.log_stream_name} cfnresponse.send(event, context, cfnresponse.FAILED, responseData) else: response_msg = "Successfully Added Lambda(" + LambdaFunctionARN + ") as Target" log.info(response_msg) # TODO: SIGNAL BACK TO CLOUDFORMATION log.info("Trying to signal SUCCESS back to cloudformation.") responseData = {"Message" : response_msg, "Function" : context.log_stream_name} cfnresponse.send(event, context, cfnresponse.SUCCESS, responseData) # log the end of the create event log.info ("End of '" + str(event['RequestType']) + "' Event") elif "Delete" in str(event['RequestType']): # print the event type sent from cloudformation log.info ("'Delete' event was sent from CFN") # TODO: DELETE THINGS log.info("TODO: DELETE THINGS") # TODO: SIGNAL BACK TO CLOUDFORMATION log.info("Trying to signal SUCCESS back to cloudformation.") responseData = {"Function" : context.log_stream_name} cfnresponse.send(event, context, cfnresponse.SUCCESS, responseData) # log the end of the Delete event log.info ("End of 'Delete' Event") else: log.info ("RequestType sent from cloudformation is invalid.") log.info ("Was expecting 'Create', 'Update' or 'Delete' RequestType(s).") log.info ("The detected RequestType is : '" + str(event['RequestType']) + "'") #TODO: SIGNAL BACK TO CLOUDFORMATION log.info("Trying to signal FAILURE back to cloudformation due to invalid request type.") responseData={"Function" : context.log_stream_name} cfnresponse.send(event, context, cfnresponse.FAILED, responseData) except Exception as e: log.info ("Function failed due to the following error:") print (e) #TODO: SIGNAL BACK TO CLOUDFORMATION log.info("Trying to signal FAILURE back to cloudformation due to the error.") responseData={"Function" : context.log_stream_name} cfnresponse.send(event, context, cfnresponse.FAILED, responseData)
Nota: La funzione Lambda in custom.py esegue la chiamata all'API RegisterTargets e segnala AWS CloudFormation al termine di tale chiamata API.
6. Aggiungi i file cfnresponse.py e ** custom.py** a un file di archivio denominato ** custom.zip**. Ad esempio:
zip custom.zip cfnresponse.py custom.py
Nota: Il file custom.py utilizza la chiamata API Boto3 RegisterTargets. Questa chiamata API registra gli obiettivi specificati con il gruppo target specificato. Per ulteriori informazioni, consulta lo snippet di Python register_targets dal sito web di Boto3. Il file cfnresponse.py contiene una funzione che invia log e notifiche ad Amazon CloudWatch e AWS CloudFormation.
7. Crea un modello AWS CloudFormation utilizzando il seguente modello YAML:
Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. AWSTemplateFormatVersion: 2010-09-09 Description: HelloWorld Lambda function template for Application Load Balancer Lambda as target Parameters: # VPC in which the LoadBalancer and the LoadBalancer SecurityGroup will be created VpcId: Type: AWS::EC2::VPC::Id # Subnets in which the LoadBalancer will be created. Subnets: Type: List<AWS::EC2::Subnet::Id> # Name of the TargetGroup TargetGroupName: Type: String Default: 'MyTargets' # Name of the S3 bucket where custom.zip and website.zip are uploaded to S3BucketName: Type: String Default: you-s3-bucket-name Resources: LambdaExecutionRole: Type: AWS::IAM::Role Properties: AssumeRolePolicyDocument: Version: '2012-10-17' Statement: - Effect: Allow Principal: Service: - lambda.amazonaws.com Action: - sts:AssumeRole Path: "/" Policies: - PolicyName: root PolicyDocument: Version: '2012-10-17' Statement: - Effect: Allow Action: - '*' Resource: '*' # Lambda function which displays an HTML page with "Hello from Lambda!" message upon invocation HelloWorldFunction1234: Type: 'AWS::Lambda::Function' Properties: Code: S3Bucket: !Ref S3BucketName S3Key: website.zip FunctionName: testLambda MemorySize: 128 Handler: index.handler Timeout: 30 Runtime: python3.7 Role: !GetAtt LambdaExecutionRole.Arn LoadBalancer: Type: AWS::ElasticLoadBalancingV2::LoadBalancer Properties: Scheme: internet-facing Subnets: !Ref Subnets SecurityGroups: - !Ref LoadBalancerSecurityGroup HttpListener: Type: 'AWS::ElasticLoadBalancingV2::Listener' Properties: DefaultActions: - TargetGroupArn: !Ref TargetGroup Type: forward LoadBalancerArn: !Ref LoadBalancer Port: 80 Protocol: HTTP LoadBalancerSecurityGroup: Type: AWS::EC2::SecurityGroup Properties: GroupDescription: Allow http to client host VpcId: !Ref VpcId SecurityGroupIngress: - IpProtocol: tcp FromPort: 80 ToPort: 80 CidrIp: 0.0.0.0/0 HelloWorldFunctionInvokePermission: Type: AWS::Lambda::Permission Properties: FunctionName: !GetAtt HelloWorldFunction1234.Arn Action: 'lambda:InvokeFunction' Principal: elasticloadbalancing.amazonaws.com SourceArn: !Sub - >- arn:aws:elasticloadbalancing:${AWS::Region}:${AWS::AccountId}:${TGFullName} - TGFullName: !GetAtt TargetGroup.TargetGroupFullName TargetGroup: Type: AWS::ElasticLoadBalancingV2::TargetGroup Properties: Name: !Ref TargetGroupName TargetType: lambda # Custom resource for Lambda function - "HelloWorldFunction1234" HelloWorld: DependsOn: [TargetGroup, HelloWorldFunctionInvokePermission] Type: Custom::HelloWorld Properties: ServiceToken: !GetAtt TestFunction.Arn # Input parameters for the Lambda function LambdaFunctionARN: !GetAtt HelloWorldFunction1234.Arn TargetGroupARN: !Sub - >- arn:aws:elasticloadbalancing:${AWS::Region}:${AWS::AccountId}:${TGFullName} - TGFullName: !GetAtt TargetGroup.TargetGroupFullName # Lambda function that performs RegisterTargets API call TestFunction: Type: AWS::Lambda::Function Properties: Code: S3Bucket: !Ref S3BucketName S3Key: custom.zip Handler: custom.lambda_handler Role: !GetAtt LambdaExecutionRole.Arn Runtime: python3.7 Timeout: '5' Outputs: Message: Description: Message returned from Lambda Value: !GetAtt - HelloWorld - Message
8. Trasmetti i tuoi valori per i parametri S3BucketName, Subnets, VpcId e TargetGroupName allo stack AWS CloudFormation che hai creato utilizzando il modello nel passaggio 7.
9. Crea lo stack.
10. Dopo aver completato tutte le chiamate API, vai alla sezione Output della consoleAWS CloudFormation e cerca il seguente messaggio:
Successfully Added Lambda(arn:aws:lambda:us-east-1:123456789:function:testLambda) as Target
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