package slogr

import "github.com/go-logr/logr/slogr"

Package slogr enables usage of a slog.Handler with logr.Logger as front-end API and of a logr.LogSink through the slog.Handler and thus slog.Logger APIs.

See the README in the top-level [./logr] package for a discussion of interoperability.

Index ¶

• func NewLogr(handler slog.Handler) logr.Logger
• func NewSlogHandler(logger logr.Logger) slog.Handler
• type SlogSink
• type Underlier

Functions ¶

func NewLogr ¶

func NewLogr(handler slog.Handler) logr.Logger

NewLogr returns a logr.Logger which writes to the slog.Handler.

The logr verbosity level is mapped to slog levels such that V(0) becomes slog.LevelInfo and V(4) becomes slog.LevelDebug.

func NewSlogHandler ¶

func NewSlogHandler(logger logr.Logger) slog.Handler

NewSlogHandler returns a slog.Handler which writes to the same sink as the logr.Logger.

The returned logger writes all records with level >= slog.LevelError as error log entries with LogSink.Error, regardless of the verbosity level of the logr.Logger:

logger := <some logr.Logger with 0 as verbosity level>
slog.New(NewSlogHandler(logger.V(10))).Error(...) -> logSink.Error(...)

The level of all other records gets reduced by the verbosity level of the logr.Logger and the result is negated. If it happens to be negative, then it gets replaced by zero because a LogSink is not expected to handled negative levels:

slog.New(NewSlogHandler(logger)).Debug(...) -> logger.GetSink().Info(level=4, ...)
slog.New(NewSlogHandler(logger)).Warning(...) -> logger.GetSink().Info(level=0, ...)
slog.New(NewSlogHandler(logger)).Info(...) -> logger.GetSink().Info(level=0, ...)
slog.New(NewSlogHandler(logger.V(4))).Info(...) -> logger.GetSink().Info(level=4, ...)

Types ¶

type SlogSink ¶

type SlogSink interface {
	logr.LogSink

	Handle(ctx context.Context, record slog.Record) error
	WithAttrs(attrs []slog.Attr) SlogSink
	WithGroup(name string) SlogSink
}

SlogSink is an optional interface that a LogSink can implement to support logging through the slog.Logger or slog.Handler APIs better. It then should also support special slog values like slog.Group. When used as a slog.Handler, the advantages are:

• stack unwinding gets avoided in favor of logging the pre-recorded PC, as intended by slog
• proper grouping of key/value pairs via WithGroup
• verbosity levels > slog.LevelInfo can be recorded
• less overhead

Both APIs (logr.Logger and slog.Logger/Handler) then are supported equally well. Developers can pick whatever API suits them better and/or mix packages which use either API in the same binary with a common logging implementation.

This interface is necessary because the type implementing the LogSink interface cannot also implement the slog.Handler interface due to the different prototype of the common Enabled method.

An implementation could support both interfaces in two different types, but then additional interfaces would be needed to convert between those types in NewLogr and NewSlogHandler.

type Underlier ¶

type Underlier interface {
	// GetUnderlying returns the Handler used by the LogSink.
	GetUnderlying() slog.Handler
}

Underlier is implemented by the LogSink returned by NewLogr.

Source Files ¶

sloghandler.go slogr.go slogsink.go

Directories ¶