fix: parse userinfo provided in nomad address

[stind]

Description

I was trying to use nomad-pack with address that includes basic auth, like http://user:pass@host, and received nil pointer dereference error. That's because of the line with conf.HttpAuth.Username = user (conf.HttpAuth may be nil.)

On top of that, I realized that the address is not parsed correctly when it includes both scheme:// and userinfo: scheme://user:pass@addr would be parsed as user = "scheme", pass = "//user:pass", addr = "addr"

[hashicorp-cla]

All committers have signed the CLA.

[slonopotamus]

This is kinda... Eh. Maybe just url.Parse?

[stind]

This is kinda... Eh. Maybe just url.Parse?

more than happy to do that 👍 I'll make the change

[angrycub]

@stind Thanks for the PR. Typically the Nomad API client is configured using the DefaultConfig function of the API package.
Since the Nomad CLI uses NOMAD_HTTP_AUTH to hold the basic authentication information, we do the same for consistency's sake.

However, I think it might be nice to be able to consume all of this from the NOMAD_ADDR itself, so I'd like to talk to some folks here and see if this is something that we can bring into the Nomad API package itself.

Some quick context as to they why they're separate: Nomad itself has never (and still doesn't) support basic authentication itself. The basic authentication "support" was added for folks who are using a auth-enabled proxy in front of Nomad.