Make tmp directory configurable

[okgolove]

Hello. I use your helm chart to spin up the service.

During startup it get an error:

ℹ Cleaning up cache entries older than 7d with schedule 0 0 * * * (next run: 12/16/2024, 12:00:00 AM)                        cache-server 2:30:53 PM
ℹ 🚀 Starting GitHub Actions Cache Server (v4.0.1)                                                                           cache-server 2:30:53 PM
ℹ Using database driver: sqlite                                                                                              cache-server 2:30:53 PM
(node:94) [DEP0040] DeprecationWarning: The `punycode` module is deprecated. Please use a userland alternative instead.
(Use `node --trace-deprecation ...` to show where the warning was created)
ℹ Migrating database...                                                                                                      cache-server 2:30:53 PM
⚙ Migration results []                                                                                                       cache-server 2:30:54 PM
✔ Database migrated                                                                                                          cache-server 2:30:54 PM
ℹ Using storage driver: filesystem                                                                                           cache-server 2:30:54 PM

 ERROR  Failed to initialize storage driver: EROFS: read-only file system, mkdtemp 'github-actions-cache-serverXXXXXX'                     2:30:54 PM

  at async Object.mkdtemp (node:internal/fs/promises:1178:10)
  at async Object.setup (server/chunks/runtime.mjs:5637:21)
  at async initializeStorage (server/chunks/runtime.mjs:5924:20)
  at async server/chunks/runtime.mjs:6099:3
  at async createNitroApp (server/chunks/runtime.mjs:6474:7)
  at async server/chunks/runtime.mjs:6482:18

As far as I understand the issue is in mkdtemp function.

We mount ephemeralStorage to /tmp in deployment but app is run in /app directory which is RO because of this setting. I believe the issue is temp directory is not configurable. If it was we would have just point cache directory to /tmp.

Workaround: remove readOnlyRootFilesystem: true setting and set runAsUser: 0.