Migrate to Ubuntu 24.04

[cho-m]

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Draft until we get closer to brew 5.2.0 release date.

Related work:

• linux-headers@6.8 6.8.12 (new formula) homebrew-core#268873
• build-gcc.sh: use 10.5.0 to prepare for glibc 2.39 glibc-bootstrap#134
• Dockerfile: remove g++-12 from Ubuntu 24.04 #21613
• diagnostic: add warning on upcoming glibc 2.39 #21616
• formula_auditor: ignore implicit dep for Linux gcc audit #21765
• test/linux_runner_spec_spec: use unversioned container #21769
• workflows/actionlint: unversioned container .github#406
• workflows/clean-up-closed-prs: use unversioned container homebrew-cask#254847
• workflows/setup-commit-signing: use unversioned container actions#823
• workflows: use unversioned container for easier maintenance homebrew-core#273243
• workflows/setup-homebrew: use ubuntu-latest + ghcr.io/homebrew/brew actions#827
• Use ghcr.io/homebrew/brew:main for tests and bottling #21779
• dev-cmd/tap-new: use ubuntu-latest + ghcr.io/homebrew/brew:main #21780
• Use ubuntu-latest and add constant for arm linux runner #21787
• cmd/determine-rebottle-runners: use LINUX_CI_ARM_RUNNER homebrew-core#273430
• glibc 2.39 homebrew-core#268900
• linux-headers@6.8: remove keg-only homebrew-core#274206
• create-gcloud-instance: migrate to Ubuntu 24.04 actions#834

Homebrew/core PRs blocked by Ubuntu 22.04:

• libpqxx 8.0.0 homebrew-core#269934
• rpm 6.0.1 homebrew-core#271264
• vte3 0.84.0 homebrew-core#272337 (actually needs GCC 14, but ubuntu 24.04 has GCC 14 libstdc++ so may work though with gcc@14)
• z3 4.15.8 homebrew-core#267313
• dynare 7.0 homebrew-core#273236

Formulae with LLVM Clang workarounds to revert after migrations:

• apache-arrow
• gnome-builder
• mdk
• mysql
• opentelemetry-cpp
• protobuf
• qxmpp

Formulae with GCC dependency to rebuild after migration:

• btop (?)
• ladybug
• libunicode
• vroom

[cho-m]

Failures:

• formula audit runs on "ghcr.io/homebrew/brew:main" which is still Ubuntu 22.04 until PR is merged. Could either switch to "ghcr.io/homebrew/ubuntu24.04:main" or split docker images to separate PR.
• Bookworm (old stable) is on GCC 12. Not sure yet if there is a Linux distro running glibc < 2.39 and has libstdc++ for gcc >= 14. May need to find a way to ignore that audit failure.
• Docker image for 22.04 may need to be dropped if brew doctor cannot be ignored. Can add 26.04 pre-release image instead https://hub.docker.com/_/ubuntu#supported-tags-and-respective-dockerfile-links

[MikeMcQuaid]

• formula audit runs on "ghcr.io/homebrew/brew:main" which is still Ubuntu 22.04 until PR is merged. Could either switch to "ghcr.io/homebrew/ubuntu24.04:main"

@cho-m this makes sense to me 👍🏻.

• Bookworm (old stable) is on GCC 12. Not sure yet if there is a Linux distro running glibc < 2.39 and has libstdc++ for gcc >= 14. May need to find a way to ignore that audit failure.

Which audit failure specifically? All we're trying to do in this case is ensure that the glibc formula is installed if needed. I do think we should aim to find another distro for this.

It looks from 👇🏻 that Ubuntu 22.04 may be enough for that?

• Docker image for 22.04 may need to be dropped if brew doctor cannot be ignored. Can add 26.04 pre-release image instead hub.docker.com/_/ubuntu#supported-tags-and-respective-dockerfile-links

Yes, we should drop it and bump to versions that don't need to install glibc such as yeh the 26.04 image.

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At least some of this we can do before 5.2.0.

[cho-m]

Which audit failure specifically? All we're trying to do in this case is ensure that the glibc formula is installed if needed. I do think we should aim to find another distro for this.

The CI / test-bot run failed due to https://github.com/Homebrew/brew/actions/runs/23263094267/job/67636951864?pr=21761#step:9:73

  libfaketime
    * Formulae in homebrew/core should not have a Linux-only dependency on GCC.

Maybe that audit itself shouldn't fail for :implicit dependency? Will experiment with this locally.

EDIT: If needed, RHEL 9-based distros (e.g. Rocky 9) use glibc 2.34 + GCC 14 and will be supported for a long time.

[MikeMcQuaid]

EDIT: If needed, RHEL 9-based distros (e.g. Rocky 9) use glibc 2.34 + GCC 14 and will be supported for a long time.

Don't really care about support. If we can use e.g. Ubuntu that we've already used for this test: all the better.

[Bo98]

• Docker image for 22.04 may need to be dropped if brew doctor cannot be ignored

We had an overlap last time so should just be able to adjust it. Given its usage levels, it would be ideal to not have to skip deprecation just because of a brew doctor warning we created. There's several brew doctor warnings we skip in test bot, so can easily do that here too.

Promoting homebrew/brew image more may help this in the future. Maybe we even stop doing any more versioned ubuntu* images.

• Bookworm (old stable) is on GCC 12. Not sure yet if there is a Linux distro running glibc < 2.39 and has libstdc++ for gcc >= 14. May need to find a way to ignore that audit failure.

The point of the test is to test distros on older GCC and Glibc. The fact it's even on Bookworm is actually a mistake.

Maybe that audit itself shouldn't fail for :implicit dependency?

Yeah, this is the fix to make here. It should not be failing an audit on something that's implicitly added.

[cho-m]

The point of the test is to test distros on older GCC and Glibc. The fact it's even on Bookworm is actually a mistake.

Debian oldstable does change with every new release (2 years?). Can switch it to a fixed major version, maybe Ubuntu 22.04 or Debian bookworm assuming Docker Hub image isn't planned for removal.

Yeah I think this is the fix. It should not be failing an audit on something that's implicitly added.

Can do next run with 22.04 restored as fix should be in.

[MikeMcQuaid]

Given its usage levels, it would be ideal to not have to skip deprecation just because of a brew doctor warning we created. There's several brew doctor warnings we skip in test bot, so can easily do that here too.

We should just deprecate it ASAP in this case. We aren't strictly bound to our own deprecation process, particularly on Docker images where we've been more flexible in the past and no-one complained.

maybe Ubuntu 22.04

This seems ideal.

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Honestly I'm not even sure why we're publishing as many Docker images as we do. The images we create are trivial to replicate and build elsewhere and they just seem to cause us a decent amount of grief with both our CI (they are flaky) and the deprecation process.

[Bo98]

Honestly I'm not even sure why we're publishing as many Docker images as we do

Exactly why I suggested maybe not doing any more versioned ubuntu* images.

Ultimately, we set up tap-new to output ubuntu22.04 images which is in part why they are widely used right now and ideally need a deprecation period. If we avoid doing that in the future, then we can drop these things easier.

[MikeMcQuaid]

Exactly why I suggested maybe not doing any more versioned ubuntu* images.

Ultimately, we set up tap-new to output ubuntu22.04 images which is in part why they are widely used right now and ideally need a deprecation period. If we avoid doing that in the future, then we can drop these things easier.

Fair, good point. I'd be game to kick off that deprecation period literally as soon as we switch things over now.

@Bo98 remind me (and perhaps help @cho-m): how we did/should do deprecation of the previous images?

[cho-m]

Ultimately, we set up tap-new to output ubuntu22.04 images which is in part why they are widely used right now and ideally need a deprecation period. If we avoid doing that in the future, then we can drop these things easier.

I did update this in

• dev-cmd/tap-new: use ubuntu-latest + ghcr.io/homebrew/brew:main #21780

I verified it worked for a new tap I created (bottles built, commit pushed, release with bottles, etc.). Not sure if there are any edge cases that need to handled

[Bo98]

@Bo98 remind me (and perhaps help @cho-m): how we did/should do deprecation of the previous images?

18.04: b34253c

Or the 20.04 deprecation in the newer workflow layout: c9a7b62 (also drops 18.04 so ignore those changes)

[cho-m]

Looks like formula audit and test-bot jobs may still need a versioned container as rolling label will fetch old Ubuntu and trigger glibc error.

Haven't thought of any great alternative:

• ignoring glibc error during migration would allow test to pass, but this means we aren't verifying newer Ubuntu before PR merge
• could add a rolling label for "next" ubuntu and have some logic to pick it during migration PR

[Bo98]

Audit will be fixed after the homebrew-core PR merge won't it?

For test bot, I would perhaps wonder why we even need a container for them (besides Homebrew glibc test) - does it really need Homebrew/core tapped?

[cho-m]

Audit will be fixed after the homebrew-core PR merge won't it?

Yeah. I misread the error.

[cho-m]

For test bot, I would perhaps wonder why we even need a container for them (besides Homebrew glibc test) - does it really need Homebrew/core tapped?

Not familiar with test but container may simplify setup. We need system packages for build requirements and then --test-default-formula builds core formulae libfaketime and xz

[Bo98]

Oh did not realise that changed to use Homebrew/core formula, we used to have a test fixture for exactly that purpose.

[MikeMcQuaid]

For test bot, I would perhaps wonder why we even need a container for them (besides Homebrew glibc test) - does it really need Homebrew/core tapped?

Yes, we're trying to replicate the homebrew/core CI flow as closely as possible to blow up here before we blow up there.

as rolling label will fetch old Ubuntu and trigger glibc error.

Debian oldstable test-bot triggers this error so we can similarly handle it for old Ubuntu as we have for that.

[MikeMcQuaid]

Looks good to me, thanks!

[cho-m]

To be specific, the glibc problem is for our "latest" tests, i.e.

brew/.github/workflows/tests.yml

Lines 330 to 332 in c930535

	- name: test-bot (Linux x86_64)
	runs-on: ubuntu-latest
	container: ghcr.io/homebrew/brew:main

As we haven't built the new container yet by the time this PR runs.

[MikeMcQuaid]

As we haven't built the new container yet by the time this PR runs.

Ah, gotcha. Fine to comment that out in this PR and then change it in the next. Ideally we'd have a better flow than that, though.

[cho-m]

We still have ubuntu24.04 image so switched back to that in tests.yml. Will need to figure out a better alternative for Ubuntu 26.04 if we want to get rid of these extra images.

Also updated Support Tiers documentation for glibc versions. I do want to find a way to use templates for these so we can avoid having to update versions manually. However, not essential as documentation can always be updated separately if we forget to handle in main PR.

Tempted to also remove default version from Dockerfile and make docker.yml workflow run brew to get version number to reduce total files we need to update. Ideally only need 1 file (either os.rb or moving it to a json/yaml file)

[cho-m]

Looks like Ubuntu apt install will hit tzdata prompt unlike Debian. May be some difference in setup or DEBIAN_FRONTEND default.

EDIT: also need

• linux-headers@6.8: remove keg-only homebrew-core#274206

[cho-m]

I guess we don't actually need Homebrew/core checked out given CI is running on JSON API. (EDIT: tap used for brew audit but not brew install)

Looks like GitHub runner availability is limited right now as API generation is happening every hour which led to a couple run failures.

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PR is ready for whenever we want to prepare 5.2.0 release. Can un-draft it then.

[MikeMcQuaid]

Thanks @cho-m! Looks good for next release and that everything that can be done now/extracted in advance has been.

May be worth documenting this PR (in itself or another PR 🤔) inside the Linux-CI.md page as an example of what will need done to bump in future.

[cho-m]

May be worth documenting this PR (in itself or another PR 🤔) inside the Linux-CI.md page as an example of what will need done to bump in future.

Sure. I've been jotting some notes down locally. Will edit them and open PR to add to docs.

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Also, just remembered we'll need to handle self-hosted too - https://github.com/Homebrew/actions/blob/main/create-gcloud-instance/create-gcloud-instance.sh#L8.

Can keep this as a manual update given we may replace GCP. Once we figure out new self-hosted, adding a way to sync Ubuntu version number rather than hardcoding will simplify maintenance.

[Bo98]

Also, just remembered we'll need to handle self-hosted too - https://github.com/Homebrew/actions/blob/main/create-gcloud-instance/create-gcloud-instance.sh#L8.

Can keep this as a manual update given we may replace GCP. Once we figure out new self-hosted, adding a way to sync Ubuntu version number rather than hardcoding will simplify maintenance.

What date is 5.2.0? Migration of all that stuff might happen in April, only just finished the 10.15 & Node 24 stuff this week so Linux should be next up.

But even if it's before, it's a one line change so let's keep it simple rather than messing around with syncing.

[cho-m]

What date is 5.2.0? Migration of all that stuff might happen in April, only just finished the 10.15 & Node 24 stuff this week so Linux should be next up.

I don't think we have a planned date yet so migration may happen before release.

But even if it's before, it's a one line change so let's keep it simple rather than messing around with syncing.

Makes sense. GCP also changed name from ubuntu-2204-lts to ubuntu-2404-lts-amd64 so not as simple to sync without another constant.

[MikeMcQuaid]

But even if it's before, it's a one line change so let's keep it simple rather than messing around with syncing.

Would be nice to avoid a one line change that's outside this PR as these things tend to get forgotten.

[cho-m]

Un-drafting to get Copilot and other reviews, but should avoid merging until we are planning 5.2.0 release.

On side note, Ubuntu 26.04 LTS was released on 2026-04-23 so changes are in alignment with our (unofficial/proposed) idea of staying on 2nd LTS.

[Copilot]

Pull request overview

Updates Homebrew’s Linux CI/Docker baseline from Ubuntu 22.04 (Jammy) to Ubuntu 24.04 (Noble), aligning core constants, docs, and GitHub Actions workflows with the new target environment.

Changes:

• Bump Linux CI constants to Ubuntu 24.04 (glibc 2.39, GCC 13, libstdc++ 6.0.33) and update the ARM runner label.
• Update documentation to reflect the new Tier glibc expectations and CI bottling OS.
• Switch Dockerfile/workflows and test-bot containers to Ubuntu 24.04, while keeping an older Ubuntu container for glibc/gcc compatibility testing.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
Library/Homebrew/os.rb	Updates Linux CI OS/glibc/GCC/libstdc++ constants and ARM runner label.
docs/Support-Tiers.md	Raises Tier 1 Linux glibc requirement and adjusts Tier 2 glibc range accordingly.
docs/Linux-CI.md	Updates stated bottling OS to Ubuntu 24.04.
Dockerfile	Changes the default Ubuntu base version to 24.04.
.github/workflows/tests.yml	Moves test-bot containers to Ubuntu 24.04 and switches the glibc-compat test container to Ubuntu 22.04.
.github/workflows/docker.yml	Tags homebrew/brew:* from the 24.04 build and introduces 22.04 deprecation signaling + glibc-testing env handling.

Comments suppressed due to low confidence (1)

.github/workflows/tests.yml:360

• This step says it’s a slimmed-down version of the Homebrew Dockerfile, but it installs git-core whereas the Dockerfile installs git. For Ubuntu 22.04 in particular, using the same package name as the Dockerfile will keep the two in sync and avoid distro/package-name differences. Consider switching git-core to git (or update the comment if intentional).

          # Slimmed down version from the Homebrew Dockerfile
          apt-get update
          apt-get install -y --no-install-recommends \
            bzip2 \
            ca-certificates \
            curl \
            file \
            g++ \
            git-core \
            jq \

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