server: add debug to ocid

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

cmd/server/main.go

@@ -1,10 +1,12 @@
 package main
 
 import (
+	"fmt"
 	"log"
 	"net"
 	"os"
 
+	"github.com/Sirupsen/logrus"
 	"github.com/kubernetes-incubator/ocid/server"
 	"github.com/kubernetes/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
 	"github.com/urfave/cli"
@@ -36,6 +38,42 @@ func main() {
 			Value: "/var/lib/ocid/containers",
 			Usage: "ocid container dir",
 		},
+		cli.BoolFlag{
+			Name:  "debug",
+			Usage: "enable debug output for logging",
+		},
+		cli.StringFlag{
+			Name:  "log",
+			Value: "",
+			Usage: "set the log file path where internal debug information is written",
+		},
+		cli.StringFlag{
+			Name:  "log-format",
+			Value: "text",
+			Usage: "set the format used by logs ('text' (default), or 'json')",
+		},
+	}
+
+	app.Before = func(c *cli.Context) error {
+		if c.GlobalBool("debug") {
+			logrus.SetLevel(logrus.DebugLevel)
+		}
+		if path := c.GlobalString("log"); path != "" {
+			f, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY|os.O_APPEND|os.O_SYNC, 0666)
+			if err != nil {
+				return err
+			}
+			logrus.SetOutput(f)
+		}
+		switch c.GlobalString("log-format") {
+		case "text":
+			// retain logrus's default.
+		case "json":
+			logrus.SetFormatter(new(logrus.JSONFormatter))
+		default:
+			return fmt.Errorf("unknown log-format %q", c.GlobalString("log-format"))
+		}
+		return nil
 	}
 
 	app.Action = func(c *cli.Context) error {