README
¶
zerolog-hook
A lightweight and performant caller info hook for zerolog that enriches log events with function name, package name, file name, and line number — with minimal runtime overhead.
⚡ Up to 3x faster than the built-in
.Caller()method in zerolog. See Benchmarks.
Features
✅ Adds structured caller information:
• Function name
• Package name
• File name
• Line number
✅ Individually configurable fields
✅ Zero external dependencies
✅ Thread-safe caching for runtime function resolution
Installation
go get github.com/dings-things/zerolog-hook
Quick Start
import (
"os"
"github.com/rs/zerolog"
zerohook "github.com/dings-things/zerolog-hook"
)
func main() {
logger := zerolog.New(os.Stdout).
With().
Timestamp().
Logger().
Hook(zerohook.NewCallerHook(
true, // WithFunc
true, // WithFile
true, // WithLine
true, // WithPkg
))
logger.Info().Msg("Hello from logger")
}
Sample output:
{
"level": "info",
"time": "2025-04-18T12:00:00Z",
"func": "main",
"file": "main.go",
"line": 14,
"pkg": "main",
"message": "Hello from logger"
}
Use Cases
- When you need structured log context for tracing and debugging
- To replace zerolog’s
.Caller()with a faster and more flexible alternative - In performance-sensitive environments (high-frequency log generation)
Benchmarks
Tested on:
OS: Windows 10
CPU: 12th Gen Intel(R) Core(TM) i5-12600
Go: go1.21+
go test -bench=. -benchmem
| Method | Ops/sec | ns/op | B/op | allocs/op |
|---|---|---|---|---|
zerolog.Caller() |
~1.12 M | 1014 | 880 | 7 |
zerolog-hook |
~3.74 M | 308.7 | 580 | 5 |
✅ ~3x faster and ~34% less memory usage than zerolog's built-in .Caller()
API
func NewCallerHook(
withFunc bool,
withFile bool,
withLine bool,
withPkg bool,
) zerolog.Hook
withFunc: include"func"fieldwithFile: include"file"fieldwithLine: include"line"fieldwithPkg: include"pkg"field
Testing
go test -v ./...
Unit and benchmark tests are included to validate correctness and performance.
License
MIT © 2025 dings-things
Contributing
Pull requests are welcome!
Please open an issue first for major changes or discussions.
Documentation
¶
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type CallerHook ¶
type CallerHook struct {
WithFunc bool // Include function name
WithFile bool // Include filename
WithLine bool // Include line number
WithPkg bool // Include package name
}
CallerHook is a Zerolog hook that automatically adds caller information (function name, package name, filename, and line number) to the log entry. Each field can be configured individually at the time of creation.
func NewCallerHook ¶
func NewCallerHook(withFunc, withFile, withLine, withPkg bool) CallerHook
NewCallerHook creates a new instance of CallerHook
- withFunc: whether to include the function name
- withFile: whether to include the filename
- withLine: whether to include the line number
- withPkg: whether to include the package name
example:
logger := zerolog.New(os.Stdout).With().Timestamp().Logger()
logger = logger.Hook(NewCallerHook(true, true, true, true))
logger.Info().Msg("test log")
// Output: {"level":"info","time":...,"func":"captureLog","file":"caller_hook_test.go","line":...,"pkg":"loggerhook_test","message":"test log"}
Source Files