feat: all backends support making them as read-only by AJIOB · Pull Request #2705 · mozilla/sccache

AJIOB · 2026-05-11T13:45:02Z

For the local developers we want to provide the access to the remote cache server in read-only mode.

So, this PR allows read-only access to read-write storages via per-storage specific flag

codecov-commenter · 2026-05-11T13:49:28Z

Codecov Report

❌ Patch coverage is 85.54217% with 24 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.56%. Comparing base (d8a93ad) to head (e8c7396).

Files with missing lines	Patch %	Lines
src/config.rs	88.69%	13 Missing ⚠️
src/cache/cache.rs	78.43%	11 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2705      +/-   ##
==========================================
+ Coverage   74.51%   74.56%   +0.04%     
==========================================
  Files          70       70              
  Lines       39654    39795     +141     
==========================================
+ Hits        29549    29673     +124     
- Misses      10105    10122      +17

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AJIOB · 2026-06-04T14:14:45Z

Hi @sylvestre . Is it ok to you?

sylvestre · 2026-06-04T15:38:03Z

please add more tests:

No test for the check() short-circuit returning ReadOnly when rw_mode is set
No test for cache_mode_from_env_var parsing

AJIOB · 2026-06-04T15:52:28Z

Thanks, will fix the PR.

Looks like the read-only short-circuit was tested via test_operator_storage_redis_with_read_only (was added in this PR)

AJIOB · 2026-06-05T19:53:46Z

I've added 2 tests in that PR:

test_operator_storage_redis_with_read_only to check read-only short-curcuit via remote storage access.. The local storage logic wasn't changed, so not tested
test_cache_mode_from_env_var to check the logic of new function cache_mode_from_env_var

AJIOB · 2026-06-06T09:54:23Z

@sylvestre , I've fixed all you suggested, thanks. Is it OK now?

AJIOB · 2026-06-10T11:58:15Z

Hi @sylvestre,

Graceful ping about the PR

….0) (#36) This PR contains the following updates: | Package | Update | Change | |---|---|---| | [mozilla/sccache](https://github.com/mozilla/sccache) | minor | `0.15.0` → `0.16.0` | --- ### Release Notes <details> <summary>mozilla/sccache (mozilla/sccache)</summary> ### [`v0.16.0`](https://github.com/mozilla/sccache/releases/tag/v0.16.0) [Compare Source](mozilla/sccache@v0.15.0...v0.16.0) ##### sccache 0.16.0 ##### Summary sccache 0.16.0 is a smaller, stabilizing release on top of 0.15.0's multi-tier caching work, with a few new capabilities: - **Read-only backends**: Any storage backend can now be marked read-only, not just a select few ([#2705](mozilla/sccache#2705)). - **Remote execution on aarch64**: Distributed/remote execution now works on Linux aarch64, including fixes for `ldd` output parsing and toolchain packaging on non-x86\_64 Linux ([#2668](mozilla/sccache#2668)). - **CUDA**: `nvcc`'s `--dependency-output` argument is now handled ([#2708](mozilla/sccache#2708)). - **Resilience**: Fall back to a direct cache write when tempfile creation on the same filesystem fails ([#2369](mozilla/sccache#2369)), and give a meaningful error when a multi-level chain references a backend that wasn't compiled in ([#2695](mozilla/sccache#2695)). - **Client efficiency**: The client and dist-client now use a single-threaded tokio runtime, avoiding a thread explosion when many short-lived clients run on many-core hosts ([#2704](mozilla/sccache#2704)). - **Correctness**: Strip `SCCACHE_BASEDIRS` from escaped-backslash paths on Windows ([#2736](mozilla/sccache#2736)), ignore empty-set environment values in config ([#2639](mozilla/sccache#2639)), and avoid the sccache wrapper when resolving the real compiler ([#2720](mozilla/sccache#2720)). - **Security/logging**: JWT keys and cert digests are now base64-encoded in logs ([#2712](mozilla/sccache#2712)), plus general logging improvements ([#2734](mozilla/sccache#2734)). Welcome to 4 new contributors! ##### Features - feat: all backends support making them as read-only by [@AJIOB](https://github.com/AJIOB) in [#2705](mozilla/sccache#2705) - Enable RE on Linux-aarch64 by [@malfet](https://github.com/malfet) in [#2668](mozilla/sccache#2668) - feat(nvcc): support argument: `--dependency-output` by [@ZRHann](https://github.com/ZRHann) in [#2708](mozilla/sccache#2708) - feat: avoid sccache wrapper when resolving compiler by [@iTrooz](https://github.com/iTrooz) in [#2720](mozilla/sccache#2720) - Fall back to direct cache write if tempfile creation on the same fs fails by [@myzhang1029](https://github.com/myzhang1029) in [#2369](mozilla/sccache#2369) - Don't wait depfiles for gcc/clang preprocessed inputs by [@AJIOB](https://github.com/AJIOB) in [#2665](mozilla/sccache#2665) ##### Fixes - fix: strip SCCACHE\_BASEDIRS from escaped-backslash paths on Windows by [@rconde01](https://github.com/rconde01) in [#2736](mozilla/sccache#2736) - fix: ignore empty-set environment values for config by [@AJIOB](https://github.com/AJIOB) in [#2639](mozilla/sccache#2639) - fix: handle disabled cache backend features in multilevel chain by [@cryptomilk](https://github.com/cryptomilk) in [#2695](mozilla/sccache#2695) - fix: use single-threaded tokio runtime in sccache (dist-)client by [@AJIOB](https://github.com/AJIOB) in [#2704](mozilla/sccache#2704) - fix: add newline when printing dist-status to stdout by [@iTrooz](https://github.com/iTrooz) in [#2710](mozilla/sccache#2710) ##### Logging - chore: encode jwt key and cert digest with base64 in logs by [@iTrooz](https://github.com/iTrooz) in [#2712](mozilla/sccache#2712) - Slightly improve logging by [@glandium](https://github.com/glandium) in [#2734](mozilla/sccache#2734) ##### Cleanup - chore: make clippy happy by [@AJIOB](https://github.com/AJIOB) in [#2727](mozilla/sccache#2727) - Extract new\_client\_runtime() helper to DRY up client runtime creation by [@sylvestre](https://github.com/sylvestre) in [#2744](mozilla/sccache#2744) ##### New Contributors - [@ZRHann](https://github.com/ZRHann) made their first contribution in [#2708](mozilla/sccache#2708) - [@myzhang1029](https://github.com/myzhang1029) made their first contribution in [#2369](mozilla/sccache#2369) - [@malfet](https://github.com/malfet) made their first contribution in [#2668](mozilla/sccache#2668) - [@rconde01](https://github.com/rconde01) made their first contribution in [#2736](mozilla/sccache#2736) **Full Changelog**: <mozilla/sccache@v0.15.0...v0.16.0> </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Reviewed-on: https://codeberg.org/towonel/towonel/pulls/36

AJIOB force-pushed the rw_mode_support_backends branch from 28a49ca to 1e6bacb Compare May 11, 2026 13:46

AJIOB force-pushed the rw_mode_support_backends branch 2 times, most recently from 56b0296 to aab1fa8 Compare May 17, 2026 14:30

AJIOB force-pushed the rw_mode_support_backends branch 3 times, most recently from 17b64d7 to b849dc1 Compare June 4, 2026 13:35

sylvestre reviewed Jun 4, 2026

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Comment thread src/config.rs Outdated

sylvestre reviewed Jun 4, 2026

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Comment thread docs/Azure.md Outdated

AJIOB force-pushed the rw_mode_support_backends branch 4 times, most recently from 884ca5d to 5e18212 Compare June 5, 2026 19:52

AJIOB requested a review from sylvestre June 9, 2026 14:34

AJIOB mentioned this pull request Jun 10, 2026

Add read-only mode for GHA backend #2732

Closed

sylvestre force-pushed the rw_mode_support_backends branch from 5e18212 to 8259009 Compare June 17, 2026 15:24

feat: all backends support making them as read-only

e8c7396

AJIOB force-pushed the rw_mode_support_backends branch from 8259009 to e8c7396 Compare June 17, 2026 16:30

sylvestre merged commit bdbab18 into mozilla:main Jun 18, 2026
50 checks passed

AJIOB deleted the rw_mode_support_backends branch June 18, 2026 18:20

BrewTestBot mentioned this pull request Jun 19, 2026

sccache 0.16.0 Homebrew/homebrew-core#288823

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feat: all backends support making them as read-only#2705

feat: all backends support making them as read-only#2705
sylvestre merged 1 commit into
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AJIOB:rw_mode_support_backends

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