add log to file

Signed-off-by: Vladimir Lavor <vlavor@cisco.com>

cmd/vpp-agent-init/initializer/initializer.go

@@ -87,7 +87,7 @@ func (i *initializer) StartVPP(statChan chan status.ProcessStatus) error {
 		}
 	}
 
-	vppLog := newPmLogger("vpp")
+	vppLog := newPmLogger("vpp", defaultLogfilePath)
 	i.vpp = i.pm.NewProcess("vpp", *vppBinaryPath, pm.Args("-c", *vppStartupConfigPath),
 		pm.Writer(vppLog, vppLog), pm.Notify(statChan), pm.AutoTerminate())
 	err := i.vpp.Start()
@@ -121,7 +121,7 @@ func (i *initializer) StartAgent(statChan chan status.ProcessStatus) error {
 		return nil
 	}
 
-	agentLog := newPmLogger("agent")
+	agentLog := newPmLogger("agent", defaultLogfilePath)
 	i.agent = i.pm.NewProcess("agent", *agentBinaryPath, pm.Args("--config-dir="+*agentConfigDir),
 		pm.Writer(agentLog, agentLog), pm.Notify(statChan), pm.AutoTerminate())
 	err := i.agent.Start()

cmd/vpp-agent-init/initializer/pmlogger.go

@@ -18,25 +18,62 @@
 package initializer
 
 import (
+	"io"
+	"log"
+	"os"
+	"sync"
+
+	"github.com/go-errors/errors"
 	"github.com/ligato/cn-infra/logging"
 	"github.com/ligato/cn-infra/logging/logrus"
-	"os"
 )
 
+const defaultLogfilePath = "/var/log/vpp-agent-init.log"
+
+var mx sync.Mutex
+
+// Process manager logger, a helper struct which can be passed to the process
+// manager writer
 type pmLogger struct {
-	log logging.Logger
+	log         logging.Logger
+	logfilePath string
 }
 
-func newPmLogger(name string) *pmLogger {
-	vppLogger := &pmLogger{
-		log: logrus.NewLogger(name),
+// Create a new process manager logger with default logfile path (if no custom is specified)
+func newPmLogger(name, logfilePath string) *pmLogger {
+	if logfilePath == "" {
+		logfilePath = defaultLogfilePath
+	}
+
+	pmLog := &pmLogger{
+		log:         logrus.NewLogger(name),
+		logfilePath: logfilePath,
 	}
-	vppLogger.log.SetOutput(os.Stdout)
-	vppLogger.log.SetLevel(logging.DebugLevel)
-	return vppLogger
+	pmLog.log.SetOutput(os.Stdout)
+	pmLog.log.SetLevel(logging.DebugLevel)
+	return pmLog
 }
 
+// Write to logfile and print given message
 func (l pmLogger) Write(p []byte) (n int, err error) {
+	mx.Lock()
+	defer mx.Unlock()
+
+	file, err := os.OpenFile(l.logfilePath, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+	if err != nil {
+		return 0, errors.Errorf("error opening file: %v", err)
+	}
+	defer func() {
+		if err := file.Close(); err != nil {
+			l.log.Errorf("error closing file %s", l.logfilePath)
+		}
+	}()
+
+	writer := io.Writer(file)
+	log.SetOutput(writer)
+	log.Printf("%s\n", p)
+
 	l.log.Debugf("%s", p)
+
 	return len(p), nil
-}
+}