Amazon S3 needs credentials in the configuration

[adlecluse]

Hi

While using the Amazon S3 functionality I came across following error

NoCredentialProviders: no valid providers in chain. Deprecated.
For verbose messaging see aws.Config.CredentialsChainVerboseErrors

I'm not sure what the best solution for this is, but when I include some credentials in the aws.Config object it works. But the NewAmazonS3Backend function has no parameter to pass credentials.

func NewAmazonS3Backend(bucket string, prefix string, region string, endpoint string, sse string) *AmazonS3Backend {
	service := s3.New(session.New(), &aws.Config{
		Credentials:      credentials.NewStaticCredentials("foo", "foo", ""), // <-- adding this fixes my issue
		Region:                        aws.String(region),
		Endpoint:                      aws.String(endpoint),
		DisableSSL:                    aws.Bool(strings.HasPrefix(endpoint, "http://")),
		S3ForcePathStyle:              aws.Bool(endpoint != ""),
	})
...

I think it should also be able to pass credentials to the function?
Or what steps should I take to have this implemented. I'm a newbie in Amazon related stuff and as there a multiple ways of creating credentials to connect to S3, I'm not sure what the best way is to fix this in a quite general way.