rust-tracing-practices

Apply the #[tracing::instrument] attribute above the function to automatically create a span for each call. Add parameters like level = "debug", err to capture error returns, and fields(user_id = user.id) for custom context.

Use level-specific macros such as tracing::info!, debug!, trace!, warn!, and error! with named key-value arguments. For example, tracing::info!(user_id = user.id, action = "login", "User logged in successfully") produces structured, filterable output.

Pass skip(password) or skip_all to the #[tracing::instrument] attribute to prevent sensitive or large parameters from being recorded in span fields. This keeps credentials and bulky data out of your telemetry.

Include the err parameter in #[tracing::instrument], which records the error return value in the span when the function fails. Pair it with tracing::error!(error = %e, ...) for detailed structured error events.

Use info! for notable operational events, debug! for development-level diagnostics, and trace! for the most granular execution detail. Choosing level-specific macros ensures appropriate visibility and lets subscribers filter output by severity.