Spring Boot Multipart File Upload Size Inconsistency

After more debugging I discovered that when I POST to the EC2 instance directly everything works as expected. Our primary and public api url makes proxies requests through Amazon's API Gateway service. This service for some reason converts the data to Base64 instead of just passing through raw binary data.

I have found documentation to update the API Gateway to passthrough binary data: here.

I am using the Content-Type value of multipart/form-data. Do not forget to also add it in your API Settings where you enable binary support.

I did not have to edit the headers options, additionally I used the default "Method Request Passthrough" template.

And finally, don't forget to deploy your api changes...

It's now working as expected.

Sorry, but many of the comments make no sense. file.size will return the size of the uploaded file in bytes, NOT the size of the request (which, yes, due to different filters could potentially be enhanced with additional information and increase in size). Spring can't just magically double the size of a PNG file (in your case adding almost another ~600kb of information on top of whatever you've sent). While I'd like to trust that you know what you're doing and the numbers you are giving us are indeed correct, to me, all evidence points to human error... please, double-, triple-, quadruple- check that you're indeed uploading the same file in all scenarios.

How did you get to 649305 bytes in the first place? Who gave you that number? Was it your code or did you actually look at the file on disk and see how big it was? The only way compression discussions make any sense in this context is if 649305 bytes is the already compressed size of the file when running locally (it's actual size on disk being 1189763 bytes) and indeed, compression not being turned on when deployed to AWS for some reason and you receive the full uncompressed file (we don't even know how you are deploying it... is it really the same as locally? Are you running a standalone .jar in both cases? Are you deploying a .war to AWS perhaps instead? Are you really running the app in the same container and container version in both cases or are you perhaps running Tomcat locally and Jetty on AWS? etc. etc. etc.). Are you sure your Postman request is not messed up and you're not sending something else by accident (or more than you think)?

EDIT:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>com.sandbox</groupId>
    <artifactId>spring-boot-file-upload</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

package com.sandbox;

import static org.springframework.http.ResponseEntity.ok;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

@SpringBootApplication
public class Application {

    public static void main(final String[] arguments) {
        SpringApplication.run(Application.class,
                              arguments);
    }

    @RestController
    class ImageRestController {

        @PostMapping(path = "/images")
        ResponseEntity<String> upload(@RequestParam(name = "file") final MultipartFile image) {
            return ok("{\"response\": \"Uploaded image having a size of '" + image.getSize() + "' byte(s).\"}");
        }
    }
}

The example is in Java because it was just faster to put together (the environment is a simple Java environment having the standalone .jar deployed - no extra configs or anything, except for the server port being on 5000). Either way, you can try it out yourself by sending POST requests to http://test123456.us-east-1.elasticbeanstalk.com/images

This is my Postman request and the response using the image you've provided:

Everything seems to be looking fine on my AWS EB instance and all the numbers add up as expected. If you are saying your setup is as simple as it sounds then I'm unfortunately just as puzzled as you are. I can only assume that there's more to what you have shared so far (however, I doubt the issue is related to Spring Boot... then it is more likely that it has to do with your AWS configs/setup).

CloudFormation Template snippet for achieving Kenny Cason's solution:

  MyApi:
    Type: AWS::Serverless::Api
    Properties:
      BinaryMediaTypes:
        - "multipart/form-data"