Smtp logger

app/initsmtpsrv.go

@@ -24,6 +24,7 @@ func (app *App) initSMTPServer(ctx context.Context) error {
 		TLSConfig:         app.cfg.TLSConfigSMTP,
 		MaxRecipients:     app.cfg.SMTPMaxRecipients,
 		BackgroundContext: app.LogBackgroundContext,
+		Logger:            app.cfg.Logger,
 		AuthorizeFunc: func(ctx context.Context, id string) (context.Context, error) {
 			tok, _, err := authtoken.Parse(id, nil)
 			if err != nil {

smtpsrv/config.go

@@ -5,6 +5,7 @@ import (
 	"crypto/tls"
 
 	"github.com/target/goalert/alert"
+	"github.com/target/goalert/util/log"
 )
 
 // Config is used to configure the SMTP server.
@@ -15,6 +16,7 @@ type Config struct {
 	MaxRecipients  int
 
 	BackgroundContext func() context.Context
+	Logger            *log.Logger
 
 	AuthorizeFunc   func(ctx context.Context, id string) (context.Context, error)
 	CreateAlertFunc func(ctx context.Context, a *alert.Alert) error

smtpsrv/server.go

@@ -2,12 +2,37 @@ package smtpsrv
 
 import (
 	"context"
+	"errors"
+	"fmt"
 	"net"
+	"strings"
 	"time"
 
 	"github.com/emersion/go-smtp"
+	"github.com/target/goalert/util/log"
 )
 
+// SMTPLogger implements the smtp.Logger interface using the main app Logger
+type SMTPLogger struct {
+	logger *log.Logger
+}
+
+// Printf adheres to smtp.Server's Logger interface while filtering out ECONNRESET errors caused by TCP health checks
+func (l *SMTPLogger) Printf(format string, v ...interface{}) {
+	s := fmt.Sprintf(format, v...)
+	if !strings.Contains(s, "read: connection reset by peer") {
+		l.logger.Error(context.Background(), errors.New(s))
+	}
+}
+
+// Print adheres to smtp.Server's Logger interface while filtering out ECONNRESET errors caused by TCP health checks
+func (l *SMTPLogger) Println(v ...interface{}) {
+	s := fmt.Sprint(v...)
+	if !strings.Contains(s, "read: connection reset by peer") {
+		l.logger.Error(context.Background(), errors.New(s))
+	}
+}
+
 // Server implements an SMTP server that creates alerts.
 type Server struct {
 	cfg Config
@@ -19,6 +44,7 @@ func NewServer(cfg Config) *Server {
 	s := &Server{cfg: cfg}
 
 	srv := smtp.NewServer(s)
+	srv.ErrorLog = &SMTPLogger{logger: cfg.Logger}
 	srv.Domain = cfg.Domain
 	srv.ReadTimeout = 10 * time.Second
 	srv.WriteTimeout = 10 * time.Second