CODEWITHSUNDEEP
amazon-web-serviceslambdaaws-lambda
gunygoogoo
gunygoogoo

Reputation: 681

Creating a REST API from Lambda Function

I have a Java based Lambda function that is running correctly via the Lambda test event with the following JSON:

    {
  "married": "true",
  "wages": "200000",
  "homeInterest": "15000",
  "propertyTaxes": "15000",
  "stateTaxes": "13000",
  "otherDeductions": "4000",
  "postalCode": "11762"
}

I then created an API via the Amazon API Gateway. When I paste the same JSON as the body of the generated URL none of fields map correctly.

The Lambda handler is using POJOs for the request and response:

public class TaxHandler implements RequestHandler<TaxRequest, TaxResponse>{

  public TaxResponse handleRequest(TaxRequest request, Context context){

When I test via the API gateway test I see the following info:

Execution log for request test-request

Tue Dec 19 02:01:16 UTC 2017 : Starting execution for request: test-invoke-request
Tue Dec 19 02:01:16 UTC 2017 : HTTP Method: POST, Resource Path: /TaxCalculation
Tue Dec 19 02:01:16 UTC 2017 : Method request path: {}
Tue Dec 19 02:01:16 UTC 2017 : Method request query string: {}
Tue Dec 19 02:01:16 UTC 2017 : Method request headers: {}
Tue Dec 19 02:01:16 UTC 2017 : Method request body before transformations: {
  "married": "true",
  "wages": "200000",
  "homeInterest": "15000",
  "propertyTaxes": "15000",
  "stateTaxes": "13000",
  "otherDeductions": "4000",
  "postalCode": "11762"
}
Tue Dec 19 02:01:16 UTC 2017 : Endpoint request URI: https://lambda.us-east-1.amazonaws.com/2015-03-31/functions/arn:aws:lambda:us-east-1:896795400074:function:TaxCalculation/invocations
Tue Dec 19 02:01:16 UTC 2017 : Endpoint request headers: {x-amzn-lambda-integration-tag=test-request, Authorization=************************************************************************************************************************************************************************************************************************************************************************************************************************7fcbc9, X-Amz-Date=20171219T020116Z, x-amzn-apigateway-api-id=07yp3njqzk, X-Amz-Source-Arn=arn:aws:execute-api:us-east-1:896795400074:07yp3njqzk/null/POST/TaxCalculation, Accept=application/json, User-Agent=AmazonAPIGateway_07yp3njqzk, X-Amz-Security-Token= [TRUNCATED]
Tue Dec 19 02:01:16 UTC 2017 : Endpoint request body after transformations: {"resource":"/TaxCalculation","path":"/TaxCalculation","httpMethod":"POST","headers":null,"queryStringParameters":null,"pathParameters":null,"stageVariables":null,"requestContext":{"path":"/TaxCalculation","accountId":"xxxxxxxx","resourceId":"v8358d","stage":"test-invoke-stage","requestId":"test-invoke-request","identity":{"cognitoIdentityPoolId":null,"cognitoIdentityId":null,"apiKey":"test-invoke-api-key","cognitoAuthenticationType":null,"userArn":"arn:aws:iam::xxxxx:user/tvfoodmaps_aws","apiKeyId":"test-invoke-api-key-id","userAgent":"Apache-HttpClient/4.5.x (Java/1.8.0_144)","accountId":"896795400074","caller":"AIDAINMSXKH5AWAQ7NX36","sourceIp":"test-invoke-source-ip","accessKey":"ASIAIHXWW4BOHGXESRNQ","cognitoAuthenticationProvider":null,"user":"AIDAINMSXKH5AWAQ7NX36"},"resourcePath":"/TaxCalculation","httpMethod":"POST","apiId":"07yp3njqzk"},"body":"{\n  \"married\": \"true\",\n  \"wages\": \"200000\",\n  \"homeInterest\": \"15000\",\n  \"propertyTa [TRUNCATED]
Tue Dec 19 02:01:16 UTC 2017 : Sending request to https://lambda.us-east-1.amazonaws.com/2015-03-31/functions/arn:aws:lambda:us-east-1:896795400074:function:TaxCalculation/invocations
Tue Dec 19 02:01:16 UTC 2017 : Received response. Integration latency: 30 ms
Tue Dec 19 02:01:16 UTC 2017 : Endpoint response body before transformations: {"savings":565.0,"owedTaxes17":-635.0,"owedTaxes18":-1200.0,"effectiveRate17":0.0,"effectiveRate18":0.0}
Tue Dec 19 02:01:16 UTC 2017 : Endpoint response headers: {X-Amz-Executed-Version=$LATEST, x-amzn-Remapped-Content-Length=0, Connection=keep-alive, x-amzn-RequestId=7f8a1b13-e460-11e7-84cf-d1c3e8d3eaf5, Content-Length=104, Date=Tue, 19 Dec 2017 02:01:16 GMT, X-Amzn-Trace-Id=root=1-5a3872ec-1b9d875d8cc2fded5c30da46;sampled=0, Content-Type=application/json}
Tue Dec 19 02:01:16 UTC 2017 : Execution failed due to configuration error: Malformed Lambda proxy response
Tue Dec 19 02:01:16 UTC 2017 : Method completed with status: 502

How can I further debug why the function is not executing the same when called via REST instead of directly via the Lambda tester? Note: I know the error talks about the response but the issue is that the first line of my code reading the fields that should be mapped to the pojo aren't working (again, only when using the API).

Upvotes: 1

Views: 884

Answers (2)

Kannaiyan
Kannaiyan

Reputation: 13025

Looks like you have your integration with ANY and not returning the proxy response. Instead you are returning the JSON object response.

Similar problem discussed here,

https://forums.aws.amazon.com/thread.jspa?threadID=255561

And the solution to configure is documented here,

https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-set-up-simple-proxy.html#api-gateway-simple-proxy-for-lambda-output-format

Hope it helps.

Upvotes: 2

Ashan
Ashan

Reputation: 19728

You can include logging in your code so that they will be available in AWS CloudWatch to investigate the issue. Following libraries and approaches are recommended by AWS according to the documentation for Java.

Note: Also setup API Gateway logging so that it would be easier to trace any issue end to end.

Upvotes: 0

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