Missing debug and info logs in Mithril nodes

[jpraynaud]

Why

We have noticed that only error logs are available for the Mithril nodes on the recently deployed networks (testing-preview and testing-sanchonet), when there is no problem in the other networks deployed less recently (pre-release-preview, release-preprod, release-mainnet).

What

Investigate the source of the problem and fix it before releasing a new distribution.

How

• Investigate the problem:
  • The problem appeared with new version of Rust 1.84.0 (released on 2025/01/09)
  • The problem is fixed in the beta version of Rust 1.85.0-beta.2
  • We don't know yet if there is a 1.84.1 fixing the problem which is under preparation
  • A quick workaround is to use only one feature for the crate for slog: "max_level_debug" (no more trace in debug) - works only when the node is built individually with cargo
  • Feature resolution is the source of the problem: one of the crate (mithril-client) is using the WARN minimum level in release and is the level used when compiled with Rust 1.84.0 (but not in other versions of Rust)
• Fix the problem