Hey all, I'm trying to upload a data class to S3 a...

# ktor

[Austin Pederson]

Hey all, I'm trying to upload a data class to S3 as JSON using a presigned URL, but I am experiencing issues with the ContentNegotiation plugin. It looks like the ContentNegotiation plugin always uses Transfer-Encoding: chunked which is a problem for S3. This limits me to having to manually serializes this object before uploading it. Is there any way to turn off this behavior? I've scoured the web but found no way to do this as of yet...

[phldavies]

It looks like it will use chunked encoding if the content length is unknown (or the headers indicate to use chunked) (at least for CIO client)

[Renan Kummer]

We use AWS SDK for Kotlin to interact with S3. While it's not a fix for your particular issue, I suggest it as an alternative solution. It works really well with Kotlin apps

[Austin Pederson]

Yeah wish we could @Renan Kummer, but this is part of a larger system which passes us the presigned URL so we can upload to S3 and we can't change that system sad panda

[Austin Pederson]

@phldavies Right, we're using OkHttp as the engine and get the same behavior. AWS doesn't support that for S3. So essentially our options are:
1. Serialize the object ourselves prior to passing to Ktor (i.e. turning the object into a JSON string)
2. Develop an interceptor which removes the Transfer-Encoding header and updates the Content-Length with a manually calculated body size
Neither of these options are particularly great so I was hoping that we'd be able to find an alternative here that would help us out sad panda

[Aleksei Tirman [JB]]

What content converter do you use? As I can see from the code, the ContentNegotiation plugin with KotlinxSerializationConverter serializes requests to the TextContent and ByteArrayContent types that have a known content length (no chunked encoding).

[Austin Pederson]

@Aleksei Tirman [JB] we're using Jackson. I was under the impression these would work similarly?

[Aleksei Tirman [JB]]

By default, the JacksonConverter streams the body by using the OutputStreamContent . You can disable streaming by passing false to the streamRequestBody parameter when calling the jackson configuration method.

[Austin Pederson]

Ahhhhh, that would make sense. I'll have to try making that change!