🔒 http4s-aws

Provides http4s request authentication using AWS Signature Version 4 signing.
The blog post A Scala Alternative to AWS SDK for Java gives an introduction.
Inspired by filosganga/http4s-aws, but with significant differences.

Usage

You can add the following lines to build.sbt to use the library.

libraryDependencies ++= Seq(
  "com.magine" %% "http4s-aws" % http4sAwsVersion,
  "com.magine" %% "http4s-aws-s3" % http4sAwsVersion
)

Make sure to replace http4sAwsVersion with a release version.
Replace %% with %%% if you are using Scala.js or Scala Native.

Signing

Create a CredentialsProvider and use AwsSigningClient to wrap an existing client.

import cats.effect.IO
import cats.effect.IOApp
import com.magine.aws.Region
import com.magine.http4s.aws.AwsServiceName
import com.magine.http4s.aws.AwsSigningClient
import com.magine.http4s.aws.CredentialsProvider
import org.http4s.ember.client.EmberClientBuilder
import org.http4s.Request

object Main extends IOApp.Simple {
  def run: IO[Unit] = {
    val client =
      for {
        client <- EmberClientBuilder.default[IO].build
        provider <- CredentialsProvider.default(client)
        region = Region.EU_WEST_1
        serviceName = AwsServiceName.Elasticsearch
        signingClient = AwsSigningClient(provider, region, serviceName)(client)
      } yield signingClient

    val request: Request[IO] =
      Request()

    client.use(_.expect[Unit](request))
  }
}

Chunking

For chunked uploads, set Transfer-Encoding: chunked and set the X-Amz-Decoded-Content-Length header to the total length of the request body. In this case, avoid setting the Content-Length header, since it will then also have to account for the signing content length.

Pre-signing

If pre-signing of requests is necessary, use AwsPresigning.

import cats.effect.IO
import cats.effect.IOApp
import com.magine.aws.Region
import com.magine.http4s.aws.AwsPresigning
import com.magine.http4s.aws.AwsServiceName
import com.magine.http4s.aws.CredentialsProvider
import org.http4s.ember.client.EmberClientBuilder
import org.http4s.Request
import scala.concurrent.duration._

object Main extends IOApp.Simple {
  def run: IO[Unit] = {
    val presigning =
      for {
        client <- EmberClientBuilder.default[IO].build
        provider <- CredentialsProvider.default(client)
        region = Region.EU_WEST_1
        serviceName = AwsServiceName.S3
        expiry = 5.minutes
        presigning = AwsPresigning(provider, region, serviceName, expiry)
      } yield presigning

    val request: Request[IO] =
      Request()

    presigning
      .use(_.presign(request))
      .map(_.uri.renderString)
      .flatMap(IO.println)
  }
}

S3

The http4s-aws-s3 module adds support for Amazon S3 multipart uploads.

import cats.effect.IO
import cats.effect.IOApp
import com.magine.aws.Region
import com.magine.http4s.aws.CredentialsProvider
import com.magine.http4s.aws.s3.S3MultipartUpload
import com.magine.http4s.aws.s3.syntax.*
import fs2.Stream
import fs2.text
import io.circe.Json
import org.http4s.MediaType
import org.http4s.ember.client.EmberClientBuilder
import org.http4s.headers.`Content-Type`

object Main extends IOApp.Simple {
  def run: IO[Unit] = {
    val multipartUpload =
      for {
        client <- EmberClientBuilder.default[IO].build
        provider <- CredentialsProvider.default(client)
        bucket = bucket"bucket"
        key = key"key"
        region = Region.EU_WEST_1
        multipartUpload = S3MultipartUpload(client, provider, region)
          .withContentType(`Content-Type`(MediaType.application.json))
          .withMaxConcurrentUploads(5)
          .uploadTo(bucket, key)
      } yield multipartUpload

    multipartUpload.use { multipartUpload =>
      Stream(Json.obj())
        .map(_.noSpaces)
        .through(text.utf8.encode)
        .through(multipartUpload)
        .compile
        .onlyOrError
        .flatMap(IO.println)
    }
  }
}

License

Copyright 2025 Magine Pro
Copyright 2026 Viktor Rudebeck

Licensed under the Apache License, Version 2.0.
Created by Viktor Rudebeck at Magine Pro and independently maintained since 2026.