[30.x] Backport ci: inline runner selection #36672

1. 
   fanquake commented at 9:21 PM on October 26, 2026: member

   Backports:

   • #35348
   • #35441
   • #35571
2. ci: switch to GitHub cache for all runners

   Cirrus is winding down and github now offers more than 10GB cache.
   
   Switch to GH cache for all runner-types. Simplify docker build arg
   construction, and reduce the number of needed action permissions.
   
   Github-Pull: #35348
   Rebased-From: c03107acf50aeada1bacdfdbf632ffce2957bff0

   322f0389a4
3. ci: use Warp cache for Docker layers

   Speeds of 1MB/s and 15 minute cached docker image pulls during builds
   are not uncommon.
   
   Warp runners provide a local GitHub Actions cache protocol proxy for
   Docker layer cache traffic. Point BuildKit's gha cache backend at that
   proxy on Warp runners so cached image layers do not have to be fetched
   from GitHub's slower cache service.
   
   Add a default for provider so other users (e.g. qa-assets) don't have to
   update this unless they use custome runners.
   
   Github-Pull: #35447
   Rebased-From: 82901981bfbaeb3f41956597e6d90daa59a0c078

   17fe6566b4
4. ci: inline runner selection

   We are currently sometimes backlogged on waiting for runner selection.
   
   Selecting Warp or GitHub-hosted runners directly from the repository context avoids serializing all CI jobs behind a metadata job. This keeps forks on public runners while allowing upstream jobs to schedule immediately on the intended runner labels.
   
   Github-Pull: #35441
   Rebased-From: 726e196ef26490115edc595973f6703e61e1295b

   4eaccf2d74
5. ci: use warp docker buildkit cache

   This was inadvertently broken in #35441
   
   Github-Pull: #35571
   Rebased-From: b552f1713add4d14c8b940a8175b6bbe19bea846

   95e321c110
6. fanquake requested review from willcl-ark on Oct 26, 2026
7. DrahtBot added the label Backport on Oct 26, 2026
8. 
   DrahtBot commented at 9:21 PM on October 26, 2026: contributor

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   External sites

   • Code coverage & benchmarks: https://corecheck.dev/bitcoin/bitcoin/pulls/36672
   • Ralph review <img src=https://review.fish.foo/assets/bitcoin/bitcoin/36672.png alt="Ralph review status"> https://git.fish.foo/bitcoin/bitcoin/pulls/36672#author-ralph

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9. fanquake added this to the milestone 30.5 on Oct 27, 2026
10. willcl-ark approved
11. 
    willcl-ark commented at 12:45 PM on October 27, 2026: member

    ACK 95e321c110544068c8318e31e7a8c61f1efd5cfa

    This LGTM.

    ci/README.md still mentions REPO_USE_WARP_RUNNERS but I don't think that's an issue worth fixing up on an old branch.

12. fanquake merged this on Oct 27, 2026
13. fanquake closed this on Oct 27, 2026

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14. fanquake deleted the branch on Oct 27, 2026

Milestone
30.5