A Brief History of Logging in Go
Márk Sági-Kazár
2023-10-27 @ Go Budapest meetup
Standard library
(Prior to 1.21)
log package
log package
- No structured logging
- No levels
- No way to change the output format or destination 1
- No context propagation
log.Fatal
Logger interface???
- Proposal from 2017
- Eventually became github.com/go-kit/log
Userland
Popular logging libraries
- Logrus
- Zap
- Zerolog
- Go-kit
- Glog
Awesome Go 1
- 62 logging related libraries
- 6 of them called
go-log(ger) - 7 of them called
log(ger)
Challenges
- Interoperability between libraries
- Dependency
hellpurgatory - Dozens of interfaces (gRPC, mysql, etc)
log/slog package
- First proposed in 2022 October
- Released in Go 1.21
Levels
Structured logging
package main
import (
"log/slog"
"os"
)
func main() {
slog.Info("Hello world!", "user", os.Getenv("USER"))
// OR
slog.Info("Hello world!", slog.String("user", os.Getenv("USER")))
}Custom handlers
package main
import (
"log/slog"
"os"
)
func main() {
logger := slog.New(slog.NewTextHandler(os.Stdout, nil))
logger.Info("Hello world!", slog.String("user", os.Getenv("USER")))
}Other features
- Context propagation
- Attach common attributes to logger
- No more
log.FatalBS!
Further reading
Final thoughts
Questions?
A Brief History of Logging in Go Márk Sági-Kazár 2023-10-27 @ Go Budapest meetup