logging

Overview ¶

Package logging constructs the *slog.Logger a process writes through, from a configuration that takes part in the layered load.

Configuration ¶

Config holds a Level and a Format and implements the config package's Merge and Finalize contract, so it loads as part of an application's configuration rather than on its own. Finalize normalizes (trims and lower-cases), applies defaults (info, text), reads the environment overrides named by the configuration's Env value, normalizes again, and validates. A value from a file or a shell therefore validates identically in any casing, and a blank or whitespace-only value takes the default. NewEnv composes the standard names from a prefix; an empty name disables that one override, and a zero Env means no environment overrides at all.

Level is a string. slog.Level parses it — "debug", "INFO", and offsets such as "warn+2", case-insensitively — through Level.Slog. An empty Level is unset, distinct from "set to info"; Finalize has replaced it with a default by the time validation runs.

Construction ¶

New returns a logger writing to the caller's io.Writer, with slog.NewJSONHandler selected by FormatJSON and slog.NewTextHandler otherwise. The caller supplies the writer; a test passes a buffer.

New returns no error; Finalize is the validation point. A Config literal that skipped Finalize yields an info-level logger.

Scope ¶

Subsystems take a *slog.Logger as an ordinary dependency. The HTTP request logger is in the web package.