New Codespace based on prebuild doesn't pull in new commits

[bdotlim]

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I'm using Codespaces Prebuilds, and I have the trigger set to "On configuration change". As I understand it, the prebuild will only update on changes to the devcontainer.json / the Dockerfile that it points to. This is working as expected.

The issue I'm seeing is when I push changes to the branch (changes that don't trigger a new prebuild) and create a new codespace (see screenshots for how I'm creating it) based on the prebuild. Once the new codespace loads, it doesn't have any of the commits since the prebuild was built. I thought that when you create a new codespace, whether or not it's from a prebuild, the VM will pull in the latest commits for the branch. Am I wrong?

[osortega]

Hello @bdotlim !

This only depends on the configuration of your prebuild, you could make the prebuild to run and update for every push you do to the repository and that way all the changes will be available as soon as the action runs.

Here you can find more information about this: https://docs.github.com/en/codespaces/prebuilding-your-codespaces/about-github-codespaces-prebuilds

Hope this helps,
Osvaldo

[bdotlim]

I thought that even if you have a prebuild, creating a new codespace will pull in the latest commits. Is that not true? Will it only have the commits of when the prebuild was built?

[alyssaruth]

We've run into this problem too, and were pretty baffled by it. We had a prebuild with the trigger "On configuration change", last built on June 8th for our main branch.

If I make a fresh branch off of main, and launch a codespace for it, everything works fine - the prebuild gets correctly used, and I'm dropped into the codespace on the correct commit.

If, however, I launch a codespace on main, I'm dropped into a codespace on the June 8th commit (when the prebuild was last built). This is a bug, IMO - the prebuild exists to save the expensive effort of running through the Dockerfile to install things, not to cache the commit that gets checked out! In this situation the codespace should do a fast-forward for me, so I'm on the latest commit of the branch I launched the codespace for. This would be consistent with the behaviour for other branches, as well as being what the developer will be expecting.

you could make the prebuild to run and update for every push you do to the repository and that way all the changes will be available as soon as the action runs.

This is, at best, a workaround. It comes with the significant downside of doing a load of pointless work to rebuild the image on every push to main, even though no interesting aspects of the codespace have changed. This will not only waste money, but it still does not fully solve the problem. If the prebuild takes 10 minutes to create, then when I merge to main there's still a 10 minute window where someone making a codespace is going to get an old commit.

[devjgm]

I also was surprised by this problem. I have a devcontainer prebuild setup to trigger only on configuration changes. However, when we create a codespace from main using the prebuilt devcontainer, we don't see commits that happened after the prebuild was done.

I expected a current copy of the repo to be cloned, even with the prebuilt codespace.

Is this a bug or working as intended?

I think as a workaround we may be able to have a postCreateCommand that runs git pull, but it seems like we shouldn't have to do this.

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[ryanwinter]

Just ran into this problem, I'm guessing the "git pull" is the solution here? I'm suprised that it doesnt automatically do this so that you dont end up with a old codebase...