Unsupported Protocol Scheme "" in Golang with AWS S3 and goamz

I am trying to upload file bytes to S3 AWS, using the goamz/s3 package in Go (lang).

When running the following code:

    var (
        awsAuth aws.Auth
        region aws.Region
        connection s3.S3
        bucket *s3.Bucket
    )
    func init() {
    
        // Set up the AWS S3 Connection config.
        awsAuth = aws.Auth{
            AccessKey: os.Getenv("ACCESS_KEY"), // change this to yours
            SecretKey: os.Getenv("SECRET_KEY"),
        }
        fmt.Println("AWS: ", awsAuth)
    	region := aws.EUWest	
        connection := s3.New(awsAuth, region)
    
        bucket = connection.Bucket(os.Getenv("S3_BUCKET")) // change this your bucket name
    }
    func uploadToS3(filename string, byteArray *[]byte) error {
    
        var err error
        //should check if file already uploaded, encrypted by this password
        fmt.Printf("[uploadToS3] starting upload of %s\n", filename)
    
        err = bucket.Put(filename, *byteArray, "text/plain; charset=utf-8", s3.PublicRead)
        if err != nil {
            fmt.Printf("[uploadToS3] error uploading: %s\n", err)
            return err
        } else {
            fmt.Printf("[uploadToS3] done uploading %s\n", filename)    
            return nil
        }
    
        return nil // redundancy
    }

I get the error

[uploadToS3] error uploading: Put /filename: unsupported protocol scheme ""

Judging from https://stackoverflow.com/questions/26505623/unsupported-protocol-scheme-while-creating-ec2-security-group it seems that the cause is an incorrect region, however it is not the case as it is being set in init() .

Any thoughts would be greatly appreciated.

To anyone who might have the same issue. It is an error you get when the bucket name is not set. Seems stupid, but I was running this inside docker, and had forgot to tell docker what the enviroment variable was that held the bucket name. Therefore when I did echo $S3_BUCKET on my terminal, I got the bucket name, and therefore thought all was good. However I didn't test that inside the docker container. Fool on me.

I experienced this issue with the SDK V2 while setting up an AWS config to allow me to specify the AWS endpoint (I point my service to localstack during integration tests).

I resolved it by using a custom endpoint resolver.

conf, err := config.LoadDefaultConfig(
		ctx,
		config.WithRegion(region),
		config.WithRetryMaxAttempts(3),
		config.WithEndpointResolver(aws.EndpointResolverFunc(func(_, region string) (aws.Endpoint, error) {
			if internal.AwsEndpoint != "" {
				return aws.Endpoint{
					PartitionID:   "aws",
					URL:           internal.AwsEndpoint,
					SigningRegion: region,
				}, nil
			}
			// returning EndpointNotFoundError will allow the service to fallback to it's default resolution
			return aws.Endpoint{}, &aws.EndpointNotFoundError{}
		})),
	)
...
client := s3.NewFromConfig(conf, func(o *s3.Options) {
	o.UsePathStyle = true
})