Can I specify Ubuntu 22.04 and ban Github copilot?

[minwang-ai]

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I found that the Ubuntu OS version is different and it seems that it depends on when I creates the codespace.
I just create one and it is Ubuntu 24.04.3 LTS, while the codespace I created last year is Ubuntu 20.04.

Is that possible to specify Ubuntu version? I am doing course projects so it would be great to specify Ubuntu version and ban Github copilot (it would be considerred as cheating...)

[yuanyuan-qwq]

Yes, both are possible.

✅ Specify Ubuntu version

You can control the OS version using a devcontainer.json file in your repo:

{
"image": "mcr.microsoft.com/devcontainers/base:ubuntu-22.04"
}

Codespaces will then always use Ubuntu 22.04 for that repository.

✅ Disable GitHub Copilot

You can disable Copilot in Codespaces by:

Turning it off in GitHub settings → Copilot → Disable

Or uninstalling the Copilot extension inside the Codespace.

For org/class projects, admins can also block Copilot via organization policies.

Why OS changes

GitHub updates default images over time, so older Codespaces stay on old Ubuntu while new ones use newer versions.

Summary

Use devcontainer.json to lock Ubuntu version.

Disable Copilot in settings or extensions.

[minwang-ai]

Thanks yuanyuan 😊 let me have a try.

[minwang-ai]

so I just add a devcontainer.json file manually and rebuild the codespace, right?

[riteshroshann]

To add one nuance: Codespaces never guarantees a stable “default” base image — if you care about reproducibility (e.g., for a course environment), you really do need to declare the base image in a devcontainer.json, otherwise GitHub will upgrade it over time as you observed. Pinning something like:

{
  "image": "mcr.microsoft.com/devcontainers/base:ubuntu-22.04"
}

gives you deterministic Ubuntu 22.04 regardless of when the Codespace is created. You can also go further and pin toolchains, shells, package versions, or even disable updates entirely by switching to Dockerfile-based builds.

On the Copilot side: disabling from settings or uninstalling the extension works for individuals; for academic settings where Copilot is considered assistance, instructors can enforce a policy at the organization level so students don’t have to manually police their environment.

Out of curiosity, are you looking to standardize the environment only for yourself, or for an entire class cohort so everyone runs identical Ubuntu images during evaluation?

[minwang-ai]

I am just doing it for myself 😊 I am a student.
We need to submit the project code to Gradescope.
Could you see the Github enviroment link or only I can see that?

Could you please clarify this sentence? Is the devcontainer.json not enough? I am confused🙈

"You can also go further and pin toolchains, shells, package versions, or even disable updates entirely by switching to Dockerfile-based builds."

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