SAM AWS Lambda Python: gateway api - handle binary form upload - aws-lambda

Question

SAM AWS Lambda Python: I create a function that receive a file with multipart/form-data
but when I send the following request
curl --location --request POST 'https://....execute-api.....amazonaws.com/Prod/ocrReceipt' \
--header 'Connection: keep-alive' \
--header 'Pragma: no-cache' \
--header 'Cache-Control: no-cache' \
--header 'Accept: application/json, text/plain, */*' \
--header 'User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4692.99 Safari/537.36' \
--header 'Accept-Language: en-US,en;q=0.9,he;q=0.8' \
--form 'file=#"/D:/receipt.png"'
I get the event with missing Content-Length and "isBase64Encoded": false
and my code fail because I do fp = io.BytesIO(base64.b64decode(body)) # decode
when I access the same function with the Function URL I don't get this error (i.e. Content-Length is set and "isBase64Encoded": true
How can I config the gateway api to accept multipart/form-data properly?
I tried to set multipart/form-data and multipart/* in API > Settings > Binary Media Types
but it doesn't help
Not that is says You can configure binary support for your API by specifying which media types should be treated as binary types. API Gateway will look at the Content-Type and Accept HTTP headers to decide how to handle the body.
Did I set the correct value?
Can I fix it by some setting in the SAM template?
Event:
{"resource": "/ocrReceipt", "path": "/ocrReceipt", "httpMethod": "POST", "headers": {"Accept": "application/json, text/plain, */*", "Accept-Encoding": "gzip, deflate, br", "Accept-Language": "en-US,en;q=0.9,he;q=0.8", "Cache-Control": "no-cache", "CloudFront-Forwarded-Proto": "https", "CloudFront-Is-Desktop-Viewer": "true", "CloudFront-Is-Mobile-Viewer": "false", "CloudFront-Is-SmartTV-Viewer": "false", "CloudFront-Is-Tablet-Viewer": "false", "CloudFront-Viewer-ASN": "1680", "CloudFront-Viewer-Country": "IL", "Content-Type": "multipart/form-data; boundary=--------------------------592233465752962090703619", "Host": "6y5o0gb78g.execute-api.eu-west-3.amazonaws.com", "Origin": "https://doc2txt.com", "Postman-Token": "f39dea09-b71f-47bb-aa8a-57783df2ddf1", "Pragma": "no-cache", "Referer": "https://doc2txt.com/", "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4692.99 Safari/537.36", "Via": "1.1 759e09affff41285e9585e1a31532bd4.cloudfront.net (CloudFront)", "X-Amz-Cf-Id": "5jCh7W91ayJWUf_75DfWr-IfCj2CvCobvTlshBjoqaElhVWsNmlFuA==", "X-Amzn-Trace-Id": "Root=1-63b7df99-5a343d1a16ca5cde72a47d66", "X-Forwarded-For": "176.12.157.166, 130.176.1.83", "X-Forwarded-Port": "443", "X-Forwarded-Proto": "https"}, "multiValueHeaders": {"Accept": ["application/json, text/plain, */*"], "Accept-Encoding": ["gzip, deflate, br"], "Accept-Language": ["en-US,en;q=0.9,he;q=0.8"], "Cache-Control": ["no-cache"], "CloudFront-Forwarded-Proto": ["https"], "CloudFront-Is-Desktop-Viewer": ["true"], "CloudFront-Is-Mobile-Viewer": ["false"], "CloudFront-Is-SmartTV-Viewer": ["false"], "CloudFront-Is-Tablet-Viewer": ["false"], "CloudFront-Viewer-ASN": ["1680"], "CloudFront-Viewer-Country": ["IL"], "Content-Type": ["multipart/form-data; boundary=--------------------------592233465752962090703619"], "Host": ["6y5o0gb78g.execute-api.eu-west-3.amazonaws.com"], "Origin": ["https://doc2txt.com"], "Postman-Token": ["f39dea09-b71f-47bb-aa8a-57783df2ddf1"], "Pragma": ["no-cache"], "Referer": ["https://doc2txt.com/"], "User-Agent": ["Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4692.99 Safari/537.36"], "Via": ["1.1 759e09affff41285e9585e1a31532bd4.cloudfront.net (CloudFront)"], "X-Amz-Cf-Id": ["5jCh7W91ayJWUf_75DfWr-IfCj2CvCobvTlshBjoqaElhVWsNmlFuA=="], "X-Amzn-Trace-Id": ["Root=1-63b7df99-5a343d1a16ca5cde72a47d66"], "X-Forwarded-For": ["176.12.157.166, 130.176.1.83"], "X-Forwarded-Port": ["443"], "X-Forwarded-Proto": ["https"]}, "queryStringParameters": null, "multiValueQueryStringParameters": null, "pathParameters": null, "stageVariables": null, "requestContext": {"resourceId": "7g6rs7", "resourcePath": "/ocrReceipt", "httpMethod": "POST", "extendedRequestId": "eT_iDFWXCGYFfyQ=", "requestTime": "06/Jan/2023:08:45:26 +0000", "path": "/Prod/ocrReceipt", "accountId": "899418482974", "protocol": "HTTP/1.1", "stage": "Prod", "domainPrefix": "6y5o0gb78g", "requestTimeEpoch": 1672994726594, "requestId": "8a23ce92-11fe-4e54-bbb0-5ad355130833", "identity": {"cognitoIdentityPoolId": null, "accountId": null, "cognitoIdentityId": null, "caller": null, "sourceIp": "176.12.157.166", "principalOrgId": null, "accessKey": null, "cognitoAuthenticationType": null, "cognitoAuthenticationProvider": null, "userArn": null, "userAgent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4692.99 Safari/537.36", "user": null}, "domainName": "6y5o0gb78g.execute-api.eu-west-3.amazonaws.com", "apiId": "6y5o0gb78g"}, "body": "...", "isBase64Encoded": false}
template.yaml
AWSTemplateFormatVersion: "2010-09-09"
Transform: AWS::Serverless-2016-10-31
Description: >
python3.8
Sample SAM Template for ocrSam
# More info about Globals: https://github.com/awslabs/serverless-application-model/blob/master/docs/globals.rst
Globals:
Function:
Timeout: 3
MemorySize: 128
Resources:
Doc2txtFunction:
Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
Properties:
Timeout: 60
Role: arn:aws:iam::899418482974:role/service-role/ocrReceipt-role-v2edsg0i
PackageType: Image
Architectures:
- x86_64
Events:
Doc2txt:
Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
Properties:
Path: /ocrReceipt
Method: ANY
Metadata:
Dockerfile: Dockerfile
DockerContext: ./doc2txt
DockerTag: python3.8-v1
Outputs:
# ServerlessRestApi is an implicit API created out of Events key under Serverless::Function
# Find out more about other implicit resources you can reference within SAM
# https://github.com/awslabs/serverless-application-model/blob/master/docs/internals/generated_resources.rst#api
Doc2txtApi:
Description: "API Gateway endpoint URL for Prod stage for Doc2txt function"
Value: !Sub "https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/ocrReceipt/"
Doc2txtFunction:
Description: "Doc2txt Lambda Function ARN"
Value: !GetAtt Doc2txtFunction.Arn
Doc2txtFunctionIamRole:
Description: "Implicit IAM Role created for Doc2txt function"
Value: arn:aws:iam::899418482974:role/service-role/ocrReceipt-role-v2edsg0i #!GetAtt Doc2txtFunctionRole.Arn
EDIT:
I was able to get "isBase64Encoded": true with the following:
Globals:
Api:
BinaryMediaTypes:
- "*/*"

Answer 1

I was able to get "isBase64Encoded": true with the following:
Globals:
Api:
BinaryMediaTypes:
- "*/*"
apparently the content-lenght is not necessary, so I just remove it from the code:
headers = {
"content-type": headers["Content-Type"],
# "content-length": headers["Content-Length"],
}
fs = cgi.FieldStorage(fp=fp, environ=environ, headers=headers)