Symptom
Build steps fail with errors indicating that a file system location is read‑only.
Cause
When using Docker BuildKit bind mounts, mounted files are intentionally read‑only. Attempting to modify the mounted proxy CA file directly results in this error.
Resolution
Do not attempt to modify the mounted certificate file.
Ensure that only derived trust artifacts (for example, the generated certificate bundle) are written to writable locations within the container.