Homebrew Cask bottle naming limits: no timezone encoding

Question

Homebrew Cask formulae define package metadata, dependencies, and installation steps in Ruby. The version directive supports explicit pinning, but the bottle naming convention uses only platform identifiers and version numbers. No timezone component appears in the filenames, so the download and extraction process is independent of the host’s regional settings.
When a user runs brew install in different time zones, log entries show timestamps adjusted to the local zone, yet the underlying package chosen remains the same. This suggests that installation logic does not incorporate date conversion, but the displayed logs do. The behavior is documented, yet there is no explicit statement confirming that timezone variations cannot affect bottle selection or caching.
Key uncertainty: does the absence of timezone data in bottle names guarantee deterministic behavior across all locales, or could locale‑dependent filename sorting influence the brew leaves output and potentially lead to non‑deterministic install paths?
Questions:

Is there any scenario where Homebrew Cask could select a different bottle based on the system’s timezone?
Could locale settings alter the order of bottles in brew leaves and affect deterministic installs?
Does the Homebrew team plan to document explicit timezone independence for bottle naming in future releases?

Tasadduq Burney · Answer

Answer
Likely explanation: Homebrew Cask bottle filenames are built from the platform identifier, the version string and a SHA‑256 hash; they contain no date, time or timezone information. Therefore the bottle that matches a given version and platform is selected without regard to the host’s local timezone.
Confirmed facts

The bottle URL is derived solely from the formula’s version and the OS/architecture, not from the system clock.
Installation logic resolves the exact bottle by its filename; no locale‑dependent sorting influences the choice.
Log timestamps shown by brew install are formatted for the user’s locale, but they do not affect which bottle is fetched.

Steps to verify deterministic behavior

Run brew install --debug  on a machine in any timezone.
Copy the bottle URL from the debug output and note the SHA‑256 hash shown.
Repeat the install on a second machine in a different timezone and compare the hashes.
If the hashes match, the bottle selection is deterministic; any observed differences are due to log formatting, not package choice.

No additional diagnostic detail is required for the current recommendation, as the bottle naming convention guarantees timezone independence.

Homebrew Cask bottle naming limits: no timezone encoding

1 answer

Answer

Confirmed facts

Steps to verify deterministic behavior

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