aws/ec2metadata: Avoid unnecessary redirect

[jasdel]

V2 port of the v1 SDK's aws-sdk-go#2037. Removes unneeded redirect when making ec2 metadata calls for ec2 instance roll credentials.

[stefansundin]

I had a thought that maybe in v2, there is no need for an sdkuri.PathJoin method to preserve the behavior.. One reason for a v2 is the ability to break things in the desire to simplify things, right?

Anyway, just a thought. :)

[jasdel]

Agreed, one of the the ways to address this is using URI.ResolveReference. This method will preserve trailing slashes when joining components of a URI path. I think using ResolveReference for v2 would be the best approach. And probably should be applied to how the SDK computes URIs in general.

[stefansundin]

Hi @jasdel,

I just gave URL.ResolveReference a quick try, and I'm not sure if it will produce the results you want. See https://play.golang.org/p/TrL2Jas6CKw

base = http://169.254.169.254/latest/meta-data/iam/security-credentials/
base + /test/ => http://169.254.169.254/test/
base + test/ => http://169.254.169.254/latest/meta-data/iam/security-credentials/test/
base + test// => http://169.254.169.254/latest/meta-data/iam/security-credentials/test//

I think you want base + /test/ to return the same as base + test/, right?