Introduce syslogger to be used with STE (#1721)

* Introduce syslogger to be used with STE

* Fix windows build

* Address reviews

Author: nakulkar-msft

common/logger_unix.go

@@ -0,0 +1,118 @@
+// +build linux darwin
+// Copyright Microsoft <wastore@microsoft.com>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package common
+
+import (
+	"fmt"
+	"runtime"
+	"log/syslog"
+
+	"github.com/Azure/azure-pipeline-go/pipeline"
+)
+
+//////////////////////////////////////////
+type sysLogger struct {
+	// minimum loglevel represents the minimum severity of log messages which can be logged to Job Log file.
+	// any message with severity higher than this will be ignored.
+	jobID             JobID
+	minimumLevelToLog pipeline.LogLevel // The maximum customer-desired log level for this job
+	writer            *syslog.Writer      // The Job's logger
+	logSuffix         string
+	sanitizer         pipeline.LogSanitizer
+}
+
+
+func NewSysLogger(jobID JobID, minimumLevelToLog LogLevel, logSuffix string) ILoggerResetable {
+	return &sysLogger{
+		jobID:             jobID,
+		minimumLevelToLog: minimumLevelToLog.ToPipelineLogLevel(),
+		logSuffix:         logSuffix, 
+		sanitizer:         NewAzCopyLogSanitizer(),
+	}
+}
+
+func (sl *sysLogger) OpenLog() {
+	if sl.minimumLevelToLog == pipeline.LogNone {
+		return
+	    }
+	writer, err := syslog.New(syslog.LOG_NOTICE, fmt.Sprintf("%s %s", sl.logSuffix, sl.jobID.String()))
+	PanicIfErr(err)
+
+	sl.writer = writer
+	// Log the Azcopy Version
+	sl.writer.Notice("AzcopyVersion " + AzcopyVersion)
+	// Log the OS Environment and OS Architecture
+	sl.writer.Notice("OS-Environment " + runtime.GOOS)
+	sl.writer.Notice("OS-Architecture " + runtime.GOARCH)
+}
+
+func (sl *sysLogger) MinimumLogLevel() pipeline.LogLevel {
+	return sl.minimumLevelToLog
+}
+
+func (jl *sysLogger) ShouldLog(level pipeline.LogLevel) bool {
+	if level == pipeline.LogNone {
+		return false
+	}
+	return level <= jl.minimumLevelToLog
+}
+
+func (sl *sysLogger) CloseLog() {
+	if sl.minimumLevelToLog == pipeline.LogNone {
+		return
+	}
+
+	sl.writer.Notice("Closing Log")
+	sl.writer.Close()
+}
+
+
+func (sl *sysLogger) Panic(err error) {
+	sl.writer.Crit(err.Error())  // We do NOT panic here as the app would terminate;
+	//we just log it. We should never reach this line of code!
+}
+
+func (sl *sysLogger) Log(loglevel pipeline.LogLevel, msg string) {
+	if !sl.ShouldLog(loglevel) {
+		return
+	}
+	w := sl.writer
+	// ensure all secrets are redacted
+	msg = sl.sanitizer.SanitizeLogMessage(msg)
+
+	switch loglevel {
+	case pipeline.LogNone:
+		//nothing to do
+	case pipeline.LogFatal:
+		w.Emerg(msg)
+	case pipeline.LogPanic:
+		w.Crit(msg)
+	case pipeline.LogError:
+		w.Err(msg)
+	case pipeline.LogWarning:
+		w.Warning(msg)
+	case pipeline.LogInfo:
+		w.Info(msg)
+	case pipeline.LogDebug:
+		w.Debug(msg)
+	}
+}