Add credentials support

[arthurschreiber]

This is a first rough draft for credentials support in Rugged.

It tries to expose a simple as well as flexible API.

For simple use-case (like scripting/automation, where the credentials are most likely known/fixed), it allows passing a Rugged::Credentials object directly in the options hash to Rugged::Repository#clone_at:

repo = Rugged::Repository.clone_at("git@github.com:arthurschreiber/private.git", dir, {
  credentials: Rugged::Credentials::SshKey.new("git", File.expand_path("~/.ssh/id_rsa.pub"), File.expand_path("~/.ssh/id_rsa"), "passphrase")
})

For more complex use cases, like GUIs, it allows passing a proc instead. This proc can then handle the credential lookup:

repo = Rugged::Repository.clone_at("git@github.com:arthurschreiber/private.git", dir, {
  credentials: lambda { |url, username, allowed_types|
    # Dynamically create the correct credentials object, based on the url, username, and/or
    # allowed credential types.
    return Rugged::Credentials::SshKey.new("git", File.expand_path("~/.ssh/id_rsa.pub"), File.expand_path("~/.ssh/id_rsa"), "passphrase")
  }
})

This is not yet completely ready to be merged, I'm mainly looking for feedback on the API.

[arthurschreiber]

@vmg Can you take a look? This is basically ready-to-go if you are fine with the API. It even comes with a limited amount of tests based on the travis setup @cmn added to libgit2 some while ago.

[dangerp]

The comment indicates that the passphrase is optional, but it is a required parameter. It should default to ""

def initialize(username, publickey, privatekey, passphrase="")

However, this seems like too many ordered parameters to me. It is too easy to mix up the arguments ("did the publickey go first, or the privatekey?"). I would prefer hash style arguments, so the class can be initialized like so:

SshKey.new(
  username: "git", 
  public_key: File.expand_path("~/.ssh/id_rsa.pub"), 
  private_key: File.expand_path("~/.ssh/id_rsa"), 
  passphrase: "passphrase"
)

The passphrase being optional, of course. The same would apply to Credentials::Plaintext, for consistency sake.

[vmg]

Yes, I agree. A hash would be better suited for initializing the key.

[arthurschreiber]

👍 That's an easy change.

[dangerp]

This functionality would also need to be added to Rugged::Remote#connect as well, correct? For instances where you would already have a repo object perhaps the Rugged::Repository object should be initialized with them?

repo = Rugged::Repository.new("path/to/repo.git", credentials: ssh_key_object)
Rugged::Remote.lookup(repo, "origin").connect(:fetch) # uses the SSH credentials from the repo object

[arthurschreiber]

@dangerp Setting credentials on a Repository is wrong, as a repository can have multiple remotes that each can require different credentials. Instead, I'll add a way to set the credentials for a remote.

[dangerp]

@arthurschreiber good point, remotes are the correct place to add credentials.

Since this is merged, will this be added to remotes in a separate pull request? I would like to help out here, but my c skills are nonexistent.

[arthurschreiber]

@dangerp Yes, I'll ad the missing functionality in a separate pull request. I've been sick all of last week, so I've been a bit behind on this.