Julia Logging Module ↔ Deployment Logs: Interoperability Question

Goal

To reliably capture and filter deployment logs for debugging failures in Julia applications.

Constraints

The Logging module emits messages at various levels and supports custom loggers. Deployment failures are diagnosed by inspecting logs. The JULIA_DEBUG environment variable is intended to enable debug‑level logging, but its behavior across Julia versions and when combined with custom loggers is not fully defined.

Unresolved Decision

Does JULIA_DEBUG automatically apply to all submodules of a specified module, or must each submodule be listed explicitly? How does JULIA_DEBUG interact with third‑party packages such as LoggingExtras that add filtering layers? Does the default logger propagate JULIA_DEBUG settings to custom loggers?

Questions

• Will JULIA_DEBUG include debug messages from submodules of a specified module in all supported Julia versions?
• Does setting JULIA_DEBUG affect debug output when a custom FileLogger from LoggingExtras is used?
• In a multi‑module deployment, how should JULIA_DEBUG be configured to ensure consistent debug visibility across all modules?