ci: add workflow to clean caches periodically #1807

1. 
   8144225309 commented at 7:42 am on January 25, 2026: none

   Deletes all caches on the 1st and 15th of each month.

   Fixes #1691

2. in .github/workflows/caches.yml:1 in fcb90a033b

   0@@ -0,0 +1,18 @@
   1+name: Caches
   

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   ---

   

   real-or-random commented at 8:55 am on January 27, 2026:

   I think the description can be clearer here. Something like “Delete all GitHub Actions caches”
3. in .github/workflows/caches.yml:12 in fcb90a033b

    7+permissions:
    8+  actions: write
    9+
   10+jobs:
   11+  clean:
   12+    name: Delete all caches
   

   ---

   ---

   

   real-or-random commented at 8:56 am on January 27, 2026:

   I’d use the same name here because there’s really only a single job in this workflow
4. 
   real-or-random commented at 8:56 am on January 27, 2026: contributor

   Concept ACK

   I’m a bit hesitant due to the actions: write permission, but I tend to think it’s okay here. This workflow doesn’t even have an input that could be attacker controlled. And actions restricts it to GitHub Actions stuff.

5. real-or-random added the label ci on Jan 27, 2026
6. ci: add workflow to clean caches periodically

   Fixes #1691

   a27ae1ac83
7. 8144225309 force-pushed on Jan 27, 2026
8. real-or-random approved
9. 
   real-or-random commented at 10:30 am on January 27, 2026: contributor

   ACK a27ae1ac8344bdc54cdabb23128e33caf28d4f47
10. 
    real-or-random commented at 10:30 am on January 27, 2026: contributor

    cc @hebasto
11. 
    hebasto commented at 12:59 pm on January 27, 2026: member

    It’s shame that https://github.com/actions/cache does not provide an option to set a retention period explicitly.

    I think we could avoid introducing a new workflow with the write permission by simply rotating the cache keys regularly. Feel free to grab a commit from this branch.

12. 
    real-or-random commented at 2:07 pm on January 27, 2026: contributor

    I think we could avoid introducing a new workflow with the write permission by simply rotating the cache keys regularly.

    That seems cleaner indeed.

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    edit: This means for this PR:

    Approach NACK

13. 
    hebasto commented at 2:51 pm on January 27, 2026: member

    Unrelated to the changes in this PR, the current GCC snapshot has been failing self-tests since ed2924c7628343ff8b699f320a05c85bdb9c2837.

    UPDATE: The issue should be fixed in a6c3c48148dd60a09ffab57019f163180c159d65.

14. 
    hebasto commented at 10:37 pm on February 1, 2026: member

    I think we could avoid introducing a new workflow with the write permission by simply rotating the cache keys regularly.

    That seems cleaner indeed.

    Done in #1816.

15. 
    real-or-random commented at 7:58 am on February 2, 2026: contributor

    Let me close this in favor of #1816.
16. real-or-random closed this on Feb 2, 2026

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8144225309 real-or-random hebasto

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