Is it possible to create a codespace from a previous pre-build?

[jcreamer898]

Select Topic Area

Question

Body

We create several prebuilds a day, and we're trying to identify a regression in performance from the last few days.

Is it possible to create a codespace from an old prebuild from a few days ago?

[BGtulk-on]

Short answer: Not directly. GitHub Codespaces doesn’t offer a UI to spin up a new codespace from an older prebuild snapshot.

Workarounds:

• Reproduce the old environment by checking out the exact commit and devcontainer config used then trigger a fresh prebuild (or start a codespace which will build from that state).

• If you store prebuild artifacts or cache externally, restore them manually in a codespace

• Use codespace retention/stop-resume if the older codespace still exists.

[abre0101]

Hey!

Yeah, you can actually do this, though it's a bit hidden in the UI.

Quick way:

Go to your repo → Click the green "Code" button
Switch to the "Codespaces" tab
Click the "..." (three dots) next to "New codespace"
Select "New with options"
You should see a dropdown for branch/commit - pick the commit from a few days ago
If the prebuild for that commit still exists, it'll use it automatically.

The catch:

Prebuilds don't stick around forever. GitHub typically keeps them for about 30 days depending on your plan, but they can get cleaned up earlier if you're hitting storage limits. So if your prebuild from a few days ago is gone, you're out of luck.

Alternative approach:

If you know the exact commit SHA from when things were working fine, you can use the GitHub CLI:

gh codespace create --repo owner/repo --ref abc123def
Replace abc123def with your commit SHA. This will create a codespace at that point in time and use the prebuild if it's available.

Pro tip for next time:

If you're doing performance testing regularly, you might want to bump up your prebuild retention settings in your repo settings under Codespaces. That way you'll have more history to work with when hunting down regressions like this.

Hope this helps you track down that pesky regression!

[jcreamer898]

Thanks for responding!

I don't see Commits in the new codespace drowpdown.

[abre0101]

Thanks for the follow-up!

Ah, I see what you mean now. The Codespaces dropdown has changed recently, and yeah, the "Commits" option isn't there anymore in the new UI.

What happened: GitHub redesigned the Codespaces creation flow, and some of the quick-access options got moved around or simplified.

To open a Codespace on a specific commit:

Go to the commit you want (from the commit history)
Click the <> Code button on that specific commit page
Select "Create codespace on [commit-hash]"
Or you can:

Create a Codespace normally
Once inside, use the terminal: git checkout [commit-hash]
If you were using this workflow a lot: I'd suggest opening a feature request in the GitHub feedback discussions asking them to bring back the commit selector in the dropdown. The new UI is cleaner but definitely lost some power-user features.

Does that help, or were you looking for something else?

[jcreamer898]

I'm asking my co-worker that's doing this bisect, let me check them them and let you know!

[abre0101]

No problem at all! Definitely check with your coworker first - bisect debugging can get pretty involved, and you don't want to step on any toes when they're deep in the middle of tracking things down.

Whenever they're ready, just let me know what they find or if they run into any issues. I'm happy to help troubleshoot further or adjust the approach based on what's actually working (or not working) on your end.

In the meantime, I'll be here! Good luck with the regression hunt - those can be real brain teasers, but super satisfying once you track them down. 🤞