Add support for tar archives

[ketzacoatl]

Some projects distribute with .zip or .tgz, others have only a .tar (example: https://github.com/AcalephStorage/consul-alerts distributes https://bintray.com/artifact/download/darkcrux/generic/consul-alerts-latest-linux-amd64.tar)

It seems that the go-getter library only supports .tgz or .bz2, but not uncompressed .tar by itself.

[mitchellh]

This would be simple enough. No short term plans to knock this out but if anyone wants to take a look at how the other decompressors work and their respective tests, I think you'll find its quite easy to implement. I'm sure we'll do it sometime "soon" though, since it does seem like a no-brainer!

[ketzacoatl]

You are totally right @mitchellh, given what's in place, this is the simplest exercise in go. I have very little skill with go, but I will see what I can do on my own.

[ketzacoatl]

OK, I think I have it (at least it builds and tests pass), but what would be a reasonable way to test this updated build either locally with Terraform or on a remote cluster with Nomad?

[ketzacoatl]

No pressure here, but I'm curious if I did this correctly?

[ketzacoatl]

no pressure, but I am still curious.

[ketzacoatl]

With https://github.com/hashicorp/go-getter/blob/master/decompress_tar.go, does go-getter now support decompressing .tar archives? Is this issue good to close?

[upccup]

now i use go-getter download foo.tar.gz file with http link. it still report ERROR: archive: gzip: invalid header.

the foo.tar.gz is created by tar -cvf foo.tar.gz bar

[ketzacoatl]

@dadgar, can this get a review, is it still relevant?

[ketzacoatl]

Yay! Thanks @schmichael!