Make logger a separate module such that don't depend on shared module as a whole for logging (#1047)

* Make `logger` a separate module such that don't depend on `shared` module as a whole for logging

* Update `Dockerfile`

logger/logger.go

@@ -0,0 +1,49 @@
+package logger
+
+import (
+	"os"
+
+	"github.com/op/go-logging"
+)
+
+var Log = logging.MustGetLogger("mizu")
+
+var format = logging.MustStringFormatter(
+	`[%{time:2006-01-02T15:04:05.000-0700}] %{level:-5s} ▶ %{message} ▶ [%{pid} %{shortfile} %{shortfunc}]`,
+)
+
+func InitLogger(logPath string) {
+	f, err := os.OpenFile(logPath, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+	if err != nil {
+		Log.Infof("Failed to open mizu log file: %v, err %v", logPath, err)
+	}
+
+	fileLog := logging.NewLogBackend(f, "", 0)
+	consoleLog := logging.NewLogBackend(os.Stderr, "", 0)
+
+	backend2Formatter := logging.NewBackendFormatter(fileLog, format)
+
+	backend1Leveled := logging.AddModuleLevel(consoleLog)
+	backend1Leveled.SetLevel(logging.INFO, "")
+
+	logging.SetBackend(backend1Leveled, backend2Formatter)
+}
+
+func InitLoggerStd(level logging.Level) {
+	var backends []logging.Backend
+
+	stderrBackend := logging.NewLogBackend(os.Stderr, "", 0)
+	stderrFormater := logging.NewBackendFormatter(stderrBackend, format)
+	stderrLeveled := logging.AddModuleLevel(stderrFormater)
+	stderrLeveled.SetLevel(logging.ERROR, "")
+	backends = append(backends, stderrLeveled)
+
+	if level >= logging.WARNING {
+		stdoutBackend := logging.NewLogBackend(os.Stdout, "", 0)
+		stdoutFormater := logging.NewBackendFormatter(stdoutBackend, format)
+		stdoutLeveled := logging.AddModuleLevel(stdoutFormater)
+		stdoutLeveled.SetLevel(level, "")
+		backends = append(backends, stdoutLeveled)
+	}
+	logging.SetBackend(backends...)
+}