Check that repository isn't a shallow clone and show an error if it is

[kimsey0]

Description

This change detects shallow repositories and exits early with a proper error message.

Related Issue

Fixes #3188.

Motivation and Context

Since September 2022, Azure DevOps has shallow fetch enabled by default in new pipelines. GitVersion doesn't work with shallowly cloned repositories and currently shows a hard-to-debug error message about a NullReferenceException in LibGit2Sharp when encountering such a repository. A better error message will make it easier for users to find and disable shallow fetching.

How Has This Been Tested?

This has an automated test that creates a shallow copy and asserts that the correct error message is shown.

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[asbjornu]

This looks promising! How do you suggest figuring out whether a repository is a shallow clone or not? Is this information LibGit2Sharp exposes?

[arturcic]

This looks promising! How do you suggest figuring out whether a repository is a shallow clone or not? Is this information LibGit2Sharp exposes?

@asbjornu yes it seems to be supporting https://github.com/libgit2/libgit2sharp/blob/8c32b6160a49890e26100148e73c1558b0daa9af/LibGit2Sharp/RepositoryInformation.cs#L28,

Also in this PR you can see https://github.com/GitTools/GitVersion/pull/3479/files#diff-6d64c4b71b687750cfe54b49765fe58ccacf69a80c86a2e449cec0be3ebf3596R23

[asbjornu]

I would love to have a test that exercises this code somehow. Perhaps it's possible to create a shallow clone in the integration tests somehow?

[asbjornu]

This looks promising! How do you suggest figuring out whether a repository is a shallow clone or not? Is this information LibGit2Sharp exposes?

@asbjornu yes it seems to be supporting https://github.com/libgit2/libgit2sharp/blob/8c32b6160a49890e26100148e73c1558b0daa9af/LibGit2Sharp/RepositoryInformation.cs#L28,

Also in this PR you can see https://github.com/GitTools/GitVersion/pull/3479/files#diff-6d64c4b71b687750cfe54b49765fe58ccacf69a80c86a2e449cec0be3ebf3596R23

Yeah, GitHub was acting up a bit so all the changed files weren't showing in the code review. It looks like a great way to solve this problem, we just need to figure out a way to test it. :)

[arturcic]

I would love to have a test that exercises this code somehow. Perhaps it's possible to create a shallow clone in the integration tests somehow?

Something similar to the dynamic clone tests? that will clone the GitVersion repo but with the depth=1

[kimsey0]

It turns out LibGit2Sharp doesn't support setting the depth when cloning, so I had to make a work around that does a shallow pull and a garbage collection with pruning afterwards. Let me know if you see a better way to test it.

[arturcic]

It turns out LibGit2Sharp doesn't support setting the depth when cloning, so I had to make a work around that does a shallow pull and a garbage collection with pruning afterwards. Let me know if you see a better way to test it.

That is exactly what I was checking and wanted to suggest. Good catch

[arturcic]

@kimsey0 can you please rebase your PR branch on the latest main? then I think after the build succeeds we can merge

[kimsey0]

Sure thing! Done.

[arturcic]

@asbjornu please have a new look and if it works for you please merge this one

[HHobeck]

@kimsey0 Thank you very much taking the time. I have found this article https://github.blog/2020-12-21-get-up-to-speed-with-partial-clone-and-shallow-clone/ which discribes the option we have in git very good.

Following is written:

Shallow clones are the fastest way to get a copy of the working directory at the tip commit with the additional cost that fetching from these repositories is much more expensive, so we do not recommend shallow clones for developers. If you need the commit history for your build, then a treeless partial clone might work better for you than a full clone.

My question is: Does GitVersion support treeless partial clone? Or are other options available in git which boost the performance?

[kimsey0]

@HHobeck: I don't know. I have never heard of treeless partial clones before. It might be worth opening a new issue about if you would like to explore it.

[arturcic]

@HHobeck Libgit2 that is bundled in LibGit2Sharp that GitVersion uses does not have shallow clone support libgit2/libgit2#3058

[asbjornu]

Just a tiny typo, otherwise this is fantastic! 🚀 👏🏼 🎉

[mergify]

Thank you @kimsey0 for your contribution!

[kimsey0]

@asbjornu: I was going to fix the same typo in

GitVersion/docs/input/docs/reference/build-servers/bitbucket-pipelines.md

Line 41 in 2777d74

cause GitVersion will display an error message.

where I copied it from, but you were too fast at merging. 😆

[asbjornu]

@kimsey0, oh well. Let's leave that as an opportunity for you to fix in your next PR, then. 😃

[arturcic]

🎉 This issue has been resolved in version 6.0.0-beta.3 🎉
The release is available on:

• GitHub Release
• Chocolatey Package
• .Net Global Tool

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