A wrapper for the aws-sdk-go-v2 S3 client that automatically follows the x-amz-bucket-region header so that you don't have to worry about which region the bucket is in.

It also attempts to infer the correct region from S3 Express bucket names, e.g. bucketname--usw2-az1--x-s3 is in us-west-2. It also works with S3 Accelerate.

Last updated for v1.61.2.

Example usage

package main

import (
	"context"
	"fmt"
	"os"

	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/config"
	"github.com/aws/aws-sdk-go-v2/service/s3"
	s3autoregion "github.com/stefansundin/aws-sdk-go-v2-s3autoregion"
)

func main() {
	initialRegion := "us-west-1"
	bucket := "awspolicygen"
	key := "policygen.html"
	debug := true

	// Initialize the AWS SDK
	cfg, err := config.LoadDefaultConfig(
		context.TODO(),
		config.WithRegion(initialRegion),
		func(o *config.LoadOptions) error {
			o.Credentials = aws.AnonymousCredentials{}
			if debug {
				var lm aws.ClientLogMode = aws.LogRequest | aws.LogResponse
				o.ClientLogMode = &lm
			}
			return nil
		},
	)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}

	// Create a client using the s3autoregion wrapper client
	// Cache up to 50 bucket-to-region mappings
	client := s3autoregion.NewFromConfig(cfg, &s3autoregion.ExtendedOptions{
		CacheSize: 50,
	})
	fmt.Fprintf(os.Stderr, "Client region before operation: %s\n\n", client.Options().Region)

	result, err := client.HeadObject(context.TODO(), &s3.HeadObjectInput{
		Bucket: aws.String(bucket),
		Key:    aws.String(key),
	})

	region, ok := client.GetBucketRegion(bucket)
	if ok {
		fmt.Fprintf(os.Stderr, "Bucket region: %s\n\n", region)
	} else {
		fmt.Fprintf(os.Stderr, "Bucket region not found!\n\n")
	}

	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}

	fmt.Fprintf(os.Stderr, "HeadObject ContentLength: %d\n", aws.ToInt64(result.ContentLength))
}

Output should be:

Client region before operation: us-west-1

SDK 2024/08/31 13:02:11 DEBUG Request
HEAD /policygen.html HTTP/1.1
Host: awspolicygen.s3.us-west-1.amazonaws.com
User-Agent: m/E aws-sdk-go-v2/1.30.4 os/macos lang/go#1.23.0 md/GOOS#darwin md/GOARCH#arm64 api/s3#1.60.1
Accept-Encoding: identity
Amz-Sdk-Invocation-Id: 35ec0564-f60c-4c73-b415-7a008c3a78b3
Amz-Sdk-Request: attempt=1; max=3
X-Amz-Content-Sha256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

SDK 2024/08/31 13:02:12 DEBUG Request
HEAD /policygen.html HTTP/1.1
Host: awspolicygen.s3.us-east-1.amazonaws.com
User-Agent: m/E aws-sdk-go-v2/1.30.4 os/macos lang/go#1.23.0 md/GOOS#darwin md/GOARCH#arm64 api/s3#1.60.1
Accept-Encoding: identity
Amz-Sdk-Invocation-Id: c791c50d-d6e3-4702-937c-3793f3f37654
Amz-Sdk-Request: attempt=1; max=3
X-Amz-Content-Sha256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

SDK 2024/08/31 13:02:13 DEBUG Response
HTTP/1.1 200 OK
Content-Length: 12352
Accept-Ranges: bytes
Content-Type: text/html
Date: Sat, 31 Aug 2024 20:02:14 GMT
Etag: "c6f16024402e4523b140dc5907227539"
Last-Modified: Fri, 30 Aug 2024 10:26:25 GMT
Server: AmazonS3
X-Amz-Id-2: mYpZaZ2GIDhqV8ehA/kw5aFaOHq7zVCKozCuDbxGKIP3mGFHgPtMjAknV/4KMV+jlto31l8pE1k=
X-Amz-Request-Id: 6S5TJ1HYNHZDPFK5
X-Amz-Server-Side-Encryption: AES256
X-Amz-Version-Id: rGk6PFnAkEXtvKpm0PfuuR1k.XCZg2sg

Bucket region: us-east-1

HeadObject ContentLength: 12352