Question: WIndows - How to specify full path to log file name

[stuartstein777]

I have this:

func getLogger() (*zap.Logger, error) {
	dir, err := os.Executable()
	if err != nil {
		panic(err)
	}
	fullpath := filepath.Join(filepath.Dir(dir), "proxy.log")
	cfg := zap.NewProductionConfig()
	cfg.OutputPaths = []string{
		fullpath,
	}
	return cfg.Build()
}

fullpath here is C:\Users\stuarts\Source\sentilan-agent-proxy-api\proxy.log

When I try to log I get a nil dereference error. The logger that is returned is nil.

panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x0 pc=0x7ff65d95a787]

However, this works.

func getLogger() (*zap.Logger, error) {
	cfg := zap.NewProductionConfig()
	cfg.OutputPaths = []string{
		"proxy.log",
	}
	return cfg.Build()
}

This logs to proxy.log in the same folder as the .exe, But we are running this s a service and its causing the file to be logged to windows system folder (as this is the working folder when its run a service).

What am I doing wrong here? I'd like to specify a full path to log file.

[abhinav]

Hey there! It looks like Zap (or at least zap.Config) doesn't quite work on Windows yet (experimented in #999).

I'll create a separate task for Windows support, but meanwhile, you should be able to work around this issue by constructing a logger directly with zap.New instead of zap.Config. Given the above, the rough equivalent is:

enc := zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig())

ws, err := os.OpenFile(fullpath, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0666)
if err != nil { ... }

core := zapcore.NewCore(enc, ws, zapcore.InfoLevel)

logger := zap.New(core)