ci: use warpbuild cache for docker buildkit cache #35447

1. 
   willcl-ark commented at 10:29 AM on June 3, 2026: member

   We switched to GH cache recently, but the performance is beyond terrible. We have already switched the main cache actions over to warp, and this completes the transfer with the docker buildkit cache to the Warp endpoint.

2. 
   DrahtBot commented at 10:29 AM on June 3, 2026: contributor

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   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/35447.

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3. DrahtBot added the label CI failed on Jun 3, 2026
4. willcl-ark force-pushed on Jun 3, 2026
5. willcl-ark force-pushed on Jun 3, 2026
6. 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.

   82901981bf
7. willcl-ark force-pushed on Jun 3, 2026
8. willcl-ark renamed this:
   [nomerge] test alt docker cache backend
   ci: use warpbuild cache for docker buildkit cache
   on Jun 3, 2026
9. 
   willcl-ark commented at 10:44 AM on June 3, 2026: member

   I tested the PR by cache-saving the lint job, you can see the first (cache save) demo run here:

   https://github.com/bitcoin/bitcoin/actions/runs/26879120976/job/79274292423#step:5:1081

   and the second (cache restore) run here:

   https://github.com/bitcoin/bitcoin/actions/runs/26879480195/job/79275626716?pr=35447

10. 
    willcl-ark commented at 10:45 AM on June 3, 2026: member

    All jobs will have their first re-usable cache save on merge to master.

11. willcl-ark marked this as ready for review on Jun 3, 2026
12. DrahtBot removed the label CI failed on Jun 3, 2026
13. DrahtBot added the label Tests on Jun 3, 2026
14. willcl-ark assigned m3dwards on Jun 3, 2026
15. willcl-ark unassigned m3dwards on Jun 3, 2026
16. willcl-ark requested review from m3dwards on Jun 3, 2026
17. 
    m3dwards commented at 2:56 AM on June 4, 2026: contributor

    ACK 82901981bfbaeb3f41956597e6d90daa59a0c078

    Tested on my fork and also witnessed the speed improvements that we get in the main repo. Hopefully the speedup will offset the cost of the additional cache usage.

18. fanquake merged this on Jun 4, 2026
19. fanquake closed this on Jun 4, 2026

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20. 
    fanquake commented at 8:34 AM on June 4, 2026: member

    Backported to 31.x in #35331.

21. fanquake referenced this in commit d87cd03049 on Jun 4, 2026
22. 
    willcl-ark commented at 12:48 PM on June 4, 2026: member

    pre-merge median max BuildKit block time was 461.5s (with much higher outliers) post-merge median so far is 23.9s.

Contributors

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