windows_exporter/log/logger.go

94 lines
1.8 KiB
Go

package log
import (
"errors"
"fmt"
"io"
"os"
"github.com/go-kit/log"
"github.com/prometheus-community/windows_exporter/log/eventlog"
"github.com/prometheus/common/promlog"
goeventlog "golang.org/x/sys/windows/svc/eventlog"
)
// AllowedFile is a settable identifier for the output file that the logger can have.
type AllowedFile struct {
s string
w io.Writer
}
func (f *AllowedFile) String() string {
return f.s
}
// Set updates the value of the allowed format.
func (f *AllowedFile) Set(s string) error {
f.s = s
switch s {
case "stdout":
f.w = os.Stdout
case "stderr":
f.w = os.Stderr
case "eventlog":
f.w = nil
default:
file, err := os.OpenFile(s, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0200)
if err != nil {
return err
}
f.w = file
}
return nil
}
// Config is a struct containing configurable settings for the logger
type Config struct {
promlog.Config
File *AllowedFile
}
func New(config *Config) (log.Logger, error) {
if config.File == nil {
return nil, errors.New("log file undefined")
}
if config.Format == nil {
return nil, errors.New("log format undefined")
}
var (
l log.Logger
loggerFunc func(io.Writer) log.Logger
)
switch config.Format.String() {
case "json":
loggerFunc = log.NewJSONLogger
case "logfmt":
loggerFunc = log.NewLogfmtLogger
default:
return nil, fmt.Errorf("unsupported log.format %q", config.Format.String())
}
if config.File.s == "eventlog" {
w, err := goeventlog.Open("windows_exporter")
if err != nil {
return nil, err
}
l = eventlog.NewEventLogLogger(w, loggerFunc)
} else if config.File.w == nil {
panic("logger: file writer is nil")
} else {
l = loggerFunc(log.NewSyncWriter(config.File.w))
}
promlogConfig := promlog.Config{
Format: config.Format,
Level: config.Level,
}
return promlog.NewWithLogger(l, &promlogConfig), nil
}