smtp: Use zerolog hooks for warns/errors expvars #90

pkg/server/smtp/handler.go

@@ -113,7 +113,9 @@ func (s *Session) String() string {
  *  5. Goto 2
  */
 func (s *Server) startSession(id int, conn net.Conn) {
-	logger := log.With().Str("module", "smtp").Str("remote", conn.RemoteAddr().String()).
+	logger := log.Hook(logHook{}).With().
+		Str("module", "smtp").
+		Str("remote", conn.RemoteAddr().String()).
 		Int("session", id).Logger()
 	logger.Info().Msg("Starting SMTP session")
 	expConnectsCurrent.Add(1)

pkg/server/smtp/listener.go

@@ -36,6 +36,27 @@ func init() {
 	})
 }
 
+var (
+	// Raw stat collectors
+	expConnectsTotal   = new(expvar.Int)
+	expConnectsCurrent = new(expvar.Int)
+	expReceivedTotal   = new(expvar.Int)
+	expErrorsTotal     = new(expvar.Int)
+	expWarnsTotal      = new(expvar.Int)
+
+	// History of certain stats
+	deliveredHist = list.New()
+	connectsHist  = list.New()
+	errorsHist    = list.New()
+	warnsHist     = list.New()
+
+	// History rendered as comma delim string
+	expReceivedHist = new(expvar.String)
+	expConnectsHist = new(expvar.String)
+	expErrorsHist   = new(expvar.String)
+	expWarnsHist    = new(expvar.String)
+)
+
 // Server holds the configuration and state of our SMTP server
 type Server struct {
 	// TODO(#91) Refactor config items out of this struct
@@ -59,27 +80,6 @@ type Server struct {
 	waitgroup *sync.WaitGroup // Waitgroup tracks individual sessions
 }
 
-var (
-	// Raw stat collectors
-	expConnectsTotal   = new(expvar.Int)
-	expConnectsCurrent = new(expvar.Int)
-	expReceivedTotal   = new(expvar.Int)
-	expErrorsTotal     = new(expvar.Int)
-	expWarnsTotal      = new(expvar.Int)
-
-	// History of certain stats
-	deliveredHist = list.New()
-	connectsHist  = list.New()
-	errorsHist    = list.New()
-	warnsHist     = list.New()
-
-	// History rendered as comma delim string
-	expReceivedHist = new(expvar.String)
-	expConnectsHist = new(expvar.String)
-	expErrorsHist   = new(expvar.String)
-	expWarnsHist    = new(expvar.String)
-)
-
 // NewServer creates a new Server instance with the specificed config
 func NewServer(
 	cfg config.SMTP,

pkg/server/smtp/loghook.go

@@ -0,0 +1,15 @@
+package smtp
+
+import "github.com/rs/zerolog"
+
+type logHook struct{}
+
+// Run implements a zerolog hook that updates the SMTP warning/error expvars.
+func (h logHook) Run(e *zerolog.Event, level zerolog.Level, msg string) {
+	switch level {
+	case zerolog.WarnLevel:
+		expWarnsTotal.Add(1)
+	case zerolog.ErrorLevel:
+		expErrorsTotal.Add(1)
+	}
+}