Expose GetPassword via the GRPC API

[tylercloke]

GetPassword was already wired up to storage and everything, just took a bit more work to wire it through the API. This will be super helpful when building things on top of Dex as you can retrieve a password without enumerating the entire store via ListPasswords.

[srenatus]

Similar to #1272, this doesn't seem to call for a general evaluation of the direction we want the gRPC API to take, but just adds one convenient method. I'm in favor of that 😄

[srenatus]

[nit] I know it doesn't matter for presentation, but it's nicer to read this in raw form if the numbers are actually consecutive -- can you make DeletePassword a 4.?

[tylercloke]

I was trying to maintain the style, but I'm just gonna make them all 1.

[srenatus]

[nit] this line is superfluous, but being explicit is OK 👍

[tylercloke]

Yep was trying to be explicit.

[srenatus]

@ericchiang What do you think about this one?

While #1020 would resolve our need for using dex for user storage, as long as that's the case, this addition would let us simplify all the place where we're currently going with

	resp, err := s.c.ListPasswords(ctx, &api.ListPasswordReq{})
	if err != nil {
		return nil, errors.Wrap(err, "get password")
	}

	// searches returned users for user
	for _, p := range resp.Passwords {
		if p.Email == email {
			usr := users.ShowUser{
				ID:    p.UserId,
				Name:  p.Username,
				Email: p.Email,
			}
			return &usr, nil
		}
	}

	return nil, &users.NotFoundError{}

...and, since it doesn't seem too big a deal for dex' GRPC API, I'd think it's a good addition 😉

[ericchiang]

Can we do #1272 instead?

[srenatus]

@ericchiang well, these two are rather complementary... 🤔 Or am I missing something? VerifyPassword wouldn't be of much use for simplifying this, would it?

[ericchiang]

This is really oddly named. Can we either rename it "GetUserResp" and "GetUserReq"? Or can we strongly clarify that the password isn't returned?

[cippaciong]

@sagikazarmark @nabokihms I'm writing an internal component which relies on the gRPC API and I stumbled upon this issue while looking for a way the check if a certain Password/User exists in dex.

Is there any plan to include such an endpoint in the API?