Enable debug logs using a configuration parameter and put all logs in a single file (#379)

src/github.com/matrix-org/dendrite/common/log.go

@@ -16,8 +16,10 @@ package common
 
 import (
 	"os"
+	"path"
 	"path/filepath"
 
+	"github.com/matrix-org/dendrite/common/config"
 	"github.com/matrix-org/dugong"
 	"github.com/sirupsen/logrus"
 )
@@ -31,8 +33,29 @@ func (f utcFormatter) Format(entry *logrus.Entry) ([]byte, error) {
 	return f.Formatter.Format(entry)
 }
 
-// SetupLogging configures the logging format and destination(s).
-func SetupLogging(logDir string) {
+// Logrus hook which wraps another hook and filters log entries according to their level.
+// (Note that we cannot use solely logrus.SetLevel, because Dendrite supports multiple
+// levels of logging at the same time.)
+type logLevelHook struct {
+	level logrus.Level
+	logrus.Hook
+}
+
+// Levels returns all the levels supported by this hook.
+func (h *logLevelHook) Levels() []logrus.Level {
+	levels := make([]logrus.Level, 0)
+
+	for _, level := range logrus.AllLevels {
+		if level <= h.level {
+			levels = append(levels, level)
+		}
+	}
+
+	return levels
+}
+
+// SetupStdLogging configures the logging format to standard output. Typically, it is called when the config is not yet loaded.
+func SetupStdLogging() {
 	logrus.SetFormatter(&utcFormatter{
 		&logrus.TextFormatter{
 			TimestampFormat:  "2006-01-02T15:04:05.000000000Z07:00",
@@ -42,12 +65,61 @@ func SetupLogging(logDir string) {
 			DisableSorting:   false,
 		},
 	})
-	if logDir != "" {
-		_ = os.Mkdir(logDir, os.ModePerm)
-		logrus.AddHook(dugong.NewFSHook(
-			filepath.Join(logDir, "info.log"),
-			filepath.Join(logDir, "warn.log"),
-			filepath.Join(logDir, "error.log"),
+}
+
+// SetupHookLogging configures the logging hooks defined in the configuration.
+// If something fails here it means that the logging was improperly configured,
+// so we just exit with the error
+func SetupHookLogging(hooks []config.LogrusHook, componentName string) {
+	for _, hook := range hooks {
+
+		// Check we received a proper logging level
+		level, err := logrus.ParseLevel(hook.Level)
+		if err != nil {
+			logrus.Fatalf("Unrecognized logging level %s: %q", hook.Level, err)
+		}
+
+		// Perform a first filter on the logs according to the lowest level of all
+		// (Eg: If we have hook for info and above, prevent logrus from processing debug logs)
+		if logrus.GetLevel() < level {
+			logrus.SetLevel(level)
+		}
+
+		switch hook.Type {
+		case "file":
+			checkFileHookParams(hook.Params)
+			setupFileHook(hook, level, componentName)
+		default:
+			logrus.Fatalf("Unrecognized logging hook type: %s", hook.Type)
+		}
+	}
+}
+
+// File type hooks should be provided a path to a directory to store log files
+func checkFileHookParams(params map[string]interface{}) {
+	path, ok := params["path"]
+	if !ok {
+		logrus.Fatalf("Expecting a parameter \"path\" for logging hook of type \"file\"")
+	}
+
+	if _, ok := path.(string); !ok {
+		logrus.Fatalf("Parameter \"path\" for logging hook of type \"file\" should be a string")
+	}
+}
+
+// Add a new FSHook to the logger. Each component will log in its own file
+func setupFileHook(hook config.LogrusHook, level logrus.Level, componentName string) {
+	dirPath := (hook.Params["path"]).(string)
+	fullPath := filepath.Join(dirPath, componentName+".log")
+
+	if err := os.MkdirAll(path.Dir(fullPath), os.ModePerm); err != nil {
+		logrus.Fatalf("Couldn't create directory %s: %q", path.Dir(fullPath), err)
+	}
+
+	logrus.AddHook(&logLevelHook{
+		level,
+		dugong.NewFSHook(
+			fullPath,
 			&utcFormatter{
 				&logrus.TextFormatter{
 					TimestampFormat:  "2006-01-02T15:04:05.000000000Z07:00",
@@ -57,6 +129,6 @@ func SetupLogging(logDir string) {
 				},
 			},
 			&dugong.DailyRotationSchedule{GZip: true},
-		))
-	}
+		),
+	})
 }