How to response binary content with AWS Lambda Container and ASP.NET Minimal API?

[mikucat0309]

First I return Results.File(), of course Lambda response a broken webp file, because response body not encoded to base64 string.
Then I tried to return APIGatewayHttpApiV2ProxyResponse, but it serialized to JSON and embedded it into another APIGatewayHttpApiV2ProxyResponse

app.MapGet("/proof", async Task<APIGatewayHttpApiV2ProxyResponse> () =>
{
    var rawBytes = await GenerateImageAsync(doc, ImageFormat.Webp);
    var response =  new APIGatewayHttpApiV2ProxyResponse() {
        StatusCode = 200,
        Body = Convert.ToBase64String(rawBytes),
        IsBase64Encoded = true
    };
    response.SetHeaderValues("Content-Type", "image/webp", false);
    return response;
});

command used in local testing

curl http://localhost:8080/2015-03-31/functions/function/invocations -d @event.json

event.json

{
  "version": "2.0",
  "routeKey": "$default",
  "rawPath": "/proof",
  "rawQueryString": "",
  "cookies": [],
  "headers": {
    "Content-Type": "text/plain"
  },
  "queryStringParameters": {},
  "requestContext": {
    "accountId": "123456789012",
    "apiId": "api-id",
    "authentication": null,
    "authorizer": null,
    "domainName": "id.execute-api.us-east-1.amazonaws.com",
    "domainPrefix": "id",
    "http": {
      "method": "GET",
      "path": "/proof",
      "protocol": "HTTP/1.1",
      "sourceIp": "192.0.2.1",
      "userAgent": "agent"
    },
    "requestId": "id",
    "routeKey": "$default",
    "stage": "$default",
    "time": "12/Mar/2020:19:03:58 +0000",
    "timeEpoch": 1583348638390
  },
  "body": "",
  "pathParameters": {},
  "isBase64Encoded": false,
  "stageVariables": {}
}

received response

{
  "statusCode": 200,
  "headers": {
    "Content-Type": "application/json; charset=utf-8"
  },
  "body": "{\"statusCode\":200,\"headers\":{\"Content-Type\":\"image/webp\"},\"cookies\":null,\"body\":\"UklGRurSA......AAAAA\",\"isBase64Encoded\":true}",
  "isBase64Encoded": false
}

expected response

{
  "statusCode": 200,
  "headers": {
    "Content-Type": "image/webp"
  },
  "cookies": null,
  "body": "UklGRurSA......AAAAA",
  "isBase64Encoded": true
}

[ashishdhingra]

@mikucat0309 Good afternoon. Just curious, have you enabled Binary Content in your API Gateway REST API settings? Kindly refer Enabling binary support using the API Gateway console. I tested it with ASP.NET minimal API using your code and got this content when hitting the /proof endpoint in browser (here I'm setting Content-Type as image/jpg):

{
    "statusCode":200,
    "headers": {
        "Content-Type":"image/jpg"
    },
    "cookies":null,
    "body":"/9j/2wCEAA.........2BAMB/1p0qzHhv2P/9k=",
    "isBase64Encoded":true
}

Thanks,
Ashish

[mikucat0309]

Nope, because I'm using HTTP API v2, which doesn't have those settings. Thanks for your testing.

[ashishdhingra]

@mikucat0309 I'm unsure what you might be doing wrong, but I changed logic to add builder.Services.AddAWSLambdaHosting(LambdaEventSource.HttpApi); in my project and integrated it with HTTP API, it returns the following response:

{
    "statusCode":200,
    "headers":{
        "Content-Type":"image/jpg"
    },
    "cookies":null,
    "body":"/9j/2wCEAAICAgICAgICA.........p0qzHhv2P/9k=",
    "isBase64Encoded":true
}

[github-actions[bot]]

Hello! Reopening this discussion to make it searchable.