Fix broken rust cache#1477
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Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>
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Pull request overview
This PR fixes broken Rust dependency caching for PR builds. Caches saved off non-main refs are not restorable from PRs, so no workflow was effectively seeding the cache. The PR introduces a dedicated PrimeCaches.yml workflow that runs on push to main to populate all Swatinem/rust-cache shared keys used by PR workflows, makes PR reusable workflows read-only via save-if: github.ref == 'refs/heads/main', and qualifies the build-test cache key by hypervisor so KVM (Ubuntu) and mshv3 (Azure Linux 3) get distinct caches.
Changes:
- Add
PrimeCaches.ymlto prime guests, code-checks, and host caches on main pushes across all hypervisors/configs. - Add
save-if: github.ref == 'refs/heads/main'todep_build_guests.yml,dep_code_checks.yml, anddep_build_test.ymlso PR runs only read from the cache. - Add
inputs.hypervisorto the shared cache key indep_build_test.yml,dep_run_examples.yml, anddep_benchmarks.ymlso Ubuntu-based KVM runners and Azure Linux 3 mshv3 runners don't share the same Linux cache entry.
Reviewed changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.
Show a summary per file
| File | Description |
|---|---|
.github/workflows/PrimeCaches.yml |
New workflow that builds guests, code-checks, and host on main to populate every shared rust-cache key used by PR jobs. |
.github/workflows/dep_build_guests.yml |
Adds save-if: refs/heads/main so PR runs are read-only against the guests cache. |
.github/workflows/dep_code_checks.yml |
Adds save-if: refs/heads/main for both Linux and Windows code-checks caches. |
.github/workflows/dep_build_test.yml |
Adds hypervisor to the cache key and save-if: refs/heads/main, separating kvm/mshv3 caches. |
.github/workflows/dep_run_examples.yml |
Aligns the cache key with the new hypervisor-qualified scheme. |
.github/workflows/dep_benchmarks.yml |
Aligns the release cache key with the new hypervisor-qualified scheme. |
jsturtevant
reviewed
May 28, 2026
jsturtevant
approved these changes
May 28, 2026
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Our existing caching is broken because the cache is written from pr branches, but cannot be consumed by other branches
https://docs.github.com/en/actions/reference/workflows-and-actions/dependency-caching#restrictions-for-accessing-a-cache.
This PR adds a workflow on default branch (main) to prime the caches (to make it available to all branches), and makes PRs branches read-only for the caches. Also splits cache on kvm (ubuntu) and mshv (azl3) since I believe this is necessary.