Make logging configuration more extensible

Signed-off-by: Tristan Claverie <public@tclaverie.eu>

dendrite-config.yaml

@@ -121,9 +121,19 @@ tracing:
     jaeger:
         disabled: true
 
-# The configuration for logs of dendrite
+# The configuration for dendrite logs
 logging:
-    # The logging level, must be one of debug, info, warn, error, fatal, panic.
-    level: "info"
-    # The file on which save logs. If commented, logs won't be saved by dendrite and only printed to stdout
-    # path: /var/log/dendrite.log
+    # The logging type, only "file" is supported at the moment
+    - type: "file"
+      # The logging level, must be one of debug, info, warn, error, fatal, panic.
+      level: "info"
+      # Parameters for this type of log
+      params:
+        # File logging must be given a path to a directory. Each component will write to a different file. Logs are rotated each day and gzipped
+        path: "/var/log/dendrite"
+    # It is possible to have multiple logging hooks at the same time.
+    # To save only errors in a different directory, uncomment the following.
+    # - type: "file"
+    #   level: "error"
+    #   params:
+    #     path: "/var/log/dendrite/errors"

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

@@ -206,14 +206,8 @@ type Dendrite struct {
 		Jaeger jaegerconfig.Configuration `yaml:"jaeger"`
 	}
 
-	// The config for logging informations
-	Logging struct {
-		// The path to the log file
-		FPath Path `yaml:"path"`
-
-		// The logging level
-		Level string `yaml:"level"`
-	} `yaml:"logging"`
+	// The config for logging informations. Each hook will be added to logrus.
+	Logging []Hook `yaml:"logging"`
 
 	// Any information derived from the configuration options for later use.
 	Derived struct {
@@ -228,9 +222,6 @@ type Dendrite struct {
 			// registration in order to complete registration stages.
 			Params map[string]interface{} `json:"params"`
 		}
-
-		// The logrus level used for logging configuration
-		LogLevel logrus.Level
 	}
 }
 
@@ -261,6 +252,52 @@ type ThumbnailSize struct {
 	ResizeMethod string `yaml:"method,omitempty"`
 }
 
+// Hook represents a single logrus hook. At this point, only parsing and
+// verification of the proper values for type and level are done.
+// Validity/integrity checks on the parameters are done when configuring logrus.
+type Hook struct {
+	// The type of hook, currently only "file" is supported.
+	// Yaml key is "type"
+	Type string
+
+	// The level of the logs to produce. Will output only this level and above.
+	//Yaml key is "level"
+	Level logrus.Level
+
+	// The parameters for this hook.
+	// Yaml key is "params"
+	Params map[string]interface{}
+}
+
+// UnmarshalYAML performs type coercion for a logrus hook. Additionally,
+// it ensures the type is one supported.
+func (hook *Hook) UnmarshalYAML(unmarshaler func(interface{}) error) error {
+	var tmp struct {
+		Type   string                 `yaml:"type"`
+		Level  string                 `yaml:"level"`
+		Params map[string]interface{} `yaml:"params"`
+	}
+
+	if err := unmarshaler(&tmp); err != nil {
+		return err
+	}
+
+	if tmp.Type != "file" {
+		return fmt.Errorf("Unknown value for %q: %s, want one of [file]", "logging.type", tmp.Type)
+	}
+
+	level, err := logrus.ParseLevel(tmp.Level)
+	if err != nil {
+		return fmt.Errorf("Unknown value for %q: %s, want one of [debug,info,warn,error,fatal,panic]", "logging.level", tmp.Level)
+	}
+
+	hook.Type = tmp.Type
+	hook.Level = level
+	hook.Params = tmp.Params
+
+	return nil
+}
+
 // Load a yaml config file for a server run as multiple processes.
 // Checks the config to ensure that it is valid.
 // The checks are different if the server is run as a monolithic process instead
@@ -484,12 +521,6 @@ func (config *Dendrite) check(monolithic bool) error {
 		checkNotEmpty("listen.room_server", string(config.Listen.RoomServer))
 	}
 
-	if level, err := logrus.ParseLevel(config.Logging.Level); err != nil {
-		problems = append(problems, fmt.Sprintf("Invalid value for key logging.level: %s", config.Logging.Level))
-	} else {
-		config.Derived.LogLevel = level
-	}
-
 	if problems != nil {
 		return Error{problems}
 	}

src/github.com/matrix-org/dendrite/common/config/config_test.go

@@ -60,8 +60,10 @@ listen:
   sync_api: "localhost:7773"
   media_api: "localhost:7774"
 logging:
-  level: "debug"
-  path: "/my/log/dir/dendrite.log"
+  - type: "file"
+    level: "info"
+    params:
+      path: "/my/log/dir"
 `
 
 type mockReadFile map[string]string