slog/example_logvaluer_secret_test.go

// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package slog_test

import (
	"os"

	"golang.org/x/exp/slog"
	"golang.org/x/exp/slog/internal/testutil"
)

// A token is a secret value that grants permissions.
type Token string

// LogValue implements slog.LogValuer.
// It avoids revealing the token.
func (Token) LogValue() slog.Value {
	return slog.StringValue("REDACTED_TOKEN")
}

// This example demonstrates a Value that replaces itself
// with an alternative representation to avoid revealing secrets.
func ExampleLogValuer_secret() {
	t := Token("shhhh!")
	logger := slog.New(slog.HandlerOptions{ReplaceAttr: testutil.RemoveTime}.
		NewTextHandler(os.Stdout))
	logger.Info("permission granted", "user", "Perry", "token", t)

	// Output:
	// level=INFO msg="permission granted" user=Perry token=REDACTED_TOKEN
}