Cargo can't find git credentials for private repo anymore

[Boscop]

I was using private repos in my Cargo.toml before without problems.
My git installation is GitHub Desktop for windows.
But now I get this error when doing cargo build on a project that uses a private repo:

  failed to authenticate when downloading repository
attempted to find username/password via git's `credential.helper` support, but failed

Caused by:
  [7/-1] Config value 'credential.helper' was not found

Even though ssh-agent.exe is running, and when I git clone the repo manually on the cmd line, it doesn't ask me for credentials, so the underlying mechanism is working.

(It's been several months since I last tried to build this project but I didn't change anything in it from when it last compiled successfully, only updated rust/cargo (and GitHub updated itself).)

cargo 0.16.0-nightly (3568be9 2016-11-26)

[alexcrichton]

This may be due to some change in libssh2, but I'm not entirely sure how to debug unfortunately.

[jjpe]

I have gotten something similar to this today.
If I'm right, the steps to reproduce are relatively simple:

• Use Windows (I used Windows 10)
• Set git credentials
• Clone a repo or pull from one, which will succeed
• change git credentials
• clone/pull again. This time it will fail.

The core issue as far as I can see it is that there is no (easy?) way to change the credentials and have them automatically propagate to wherever they need to go (including Cargo in this case).

[alexcrichton]

This may be related to https://github.com/alexcrichton/git2-rs/issues/202, fixed in alexcrichton/ssh2-rs@0e979f8, pulled into Cargo in #4008 and going into rust-lang/rust in rust-lang/rust#41830. It may work trying the next nightly with rust-lang/rust#41830?

[Boscop]

I'm still running into this, but I haven't changed my GitHub credentials.
Now I can't depend on ANY of my private repos. It will give the above error with cargo, even though I can git clone manually in the same cmd line.
What can I try to get this working?

[alexcrichton]

@Boscop are you on Windows?

[Boscop]

Yes, Windows 8.1 with GitHub Desktop. I added the paths to git.exe and github.exe to PATH and cloning the private github repos works on the cmd line. It used to work with cargo too but not anymore.

[alexcrichton]

@Boscop right now Cargo works when cloning private repositories through using the ssh-agent protocol, do you know if that's configured with GitHub Desktop?

[Boscop]

I think so, ssh-agent.exe is running in the background.

[alexcrichton]

It may be that libgit2 isn't finding it to communicate with it? Unfortunately I don't know many details of how the ssh-agent is supposed to work on Windows or how libssh2/libgit2 implement it...

[Boscop]

Who implemented the communication between cargo and git/ssh agent?
Or who can we ask to find the cause of this?
I urgently need access to my private repos with cargo to continue my work...

Is there any info that I can provide that would be useful to debug this?
It used to work before, so I think something changed during an update of the GitHub Desktop application. But I'm not sure which version was the last working one because it auto updates without notifying me.
I just noticed that during some updates the path to git.exe changed and then I had to edit my PATH variable.
But I don't think this info is useful here because git cloning a private repo on the cmd line works, but in cargo it doesn't...

[alexcrichton]

I'm not super familiar with how it's implemented on Windows. The implementation lives in libssh2, and you may be able to poke around the source to see what's expected.

[Boscop]

@jjpe Why do you have to set git credentials? I never set git credentials and it used to work for me before.
When I do a manual git clone, it uses my ssh key which is stored on Github, and manual cloning works.
So why would I need to set any credentials?

Btw, when I do git config --global credential.helper it just prints an empty line.
And when I do git help -a | grep credential it prints:

credential
credential-manager
credential-store
credential-wincred

Why isn't cargo using my ssh key through ssh-agent.exe from GitHub Desktop (which is always running)?

[jjpe]

I'm not sure if I have to per se, it just happened to be my observation at the time as my password had been changed due to company security policy.