feat: add stdout and filesystem notification channels (#2925)

* feat: add filesystem and stdout notification channels

* configure through env vars

* compile

* feat: add compact option for debug notification channels

* fix channel mock generation

* avoid sensitive information in error message

Co-authored-by: Livio Amstutz <livio.a@gmail.com>

* add review improvements

Co-authored-by: Livio Amstutz <livio.a@gmail.com>

internal/notification/channels/smtp/channel.go

@@ -0,0 +1,149 @@
+package smtp
+
+import (
+	"crypto/tls"
+	"net"
+	"net/smtp"
+
+	"github.com/caos/zitadel/internal/notification/messages"
+
+	"github.com/caos/logging"
+	caos_errs "github.com/caos/zitadel/internal/errors"
+	"github.com/caos/zitadel/internal/notification/channels"
+	"github.com/pkg/errors"
+)
+
+var _ channels.NotificationChannel = (*Email)(nil)
+
+type Email struct {
+	smtpClient *smtp.Client
+}
+
+func InitSMTPChannel(config EmailConfig) (*Email, error) {
+	client, err := config.SMTP.connectToSMTP(config.Tls)
+	if err != nil {
+		return nil, err
+	}
+
+	logging.Log("NOTIF-4n4Ih").Debug("successfully initialized smtp email channel")
+
+	return &Email{
+		smtpClient: client,
+	}, nil
+}
+
+func (email *Email) HandleMessage(message channels.Message) error {
+	defer email.smtpClient.Close()
+	emailMsg, ok := message.(*messages.Email)
+	if !ok {
+		return caos_errs.ThrowInternal(nil, "EMAIL-s8JLs", "message is not EmailMessage")
+	}
+
+	if emailMsg.Content == "" || emailMsg.Subject == "" || len(emailMsg.Recipients) == 0 {
+		return caos_errs.ThrowInternalf(nil, "EMAIL-zGemZ", "subject, recipients and content must be set but got subject %s, recipients length %d and content length %d", emailMsg.Subject, len(emailMsg.Recipients), len(emailMsg.Content))
+	}
+
+	// To && From
+	if err := email.smtpClient.Mail(emailMsg.SenderEmail); err != nil {
+		return caos_errs.ThrowInternalf(err, "EMAIL-s3is3", "could not set sender: %v", emailMsg.SenderEmail)
+	}
+
+	for _, recp := range append(append(emailMsg.Recipients, emailMsg.CC...), emailMsg.BCC...) {
+		if err := email.smtpClient.Rcpt(recp); err != nil {
+			return caos_errs.ThrowInternalf(err, "EMAIL-s4is4", "could not set recipient: %v", recp)
+		}
+	}
+
+	// Data
+	w, err := email.smtpClient.Data()
+	if err != nil {
+		return err
+	}
+
+	_, err = w.Write([]byte(emailMsg.GetContent()))
+	if err != nil {
+		return err
+	}
+
+	err = w.Close()
+	if err != nil {
+		return err
+	}
+
+	defer logging.LogWithFields("EMAI-a1c87ec8").Debug("email sent")
+	return email.smtpClient.Quit()
+}
+
+func (smtpConfig SMTP) connectToSMTP(tlsRequired bool) (client *smtp.Client, err error) {
+	host, _, err := net.SplitHostPort(smtpConfig.Host)
+	if err != nil {
+		return nil, caos_errs.ThrowInternal(err, "EMAIL-spR56", "could not split host and port for connect to smtp")
+	}
+
+	if !tlsRequired {
+		client, err = smtpConfig.getSMPTClient()
+	} else {
+		client, err = smtpConfig.getSMPTClientWithTls(host)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	err = smtpConfig.smtpAuth(client, host)
+	if err != nil {
+		return nil, err
+	}
+	return client, nil
+}
+
+func (smtpConfig SMTP) getSMPTClient() (*smtp.Client, error) {
+	client, err := smtp.Dial(smtpConfig.Host)
+	if err != nil {
+		return nil, caos_errs.ThrowInternal(err, "EMAIL-skwos", "could not make smtp dial")
+	}
+	return client, nil
+}
+
+func (smtpConfig SMTP) getSMPTClientWithTls(host string) (*smtp.Client, error) {
+	conn, err := tls.Dial("tcp", smtpConfig.Host, &tls.Config{})
+
+	if errors.As(err, &tls.RecordHeaderError{}) {
+		logging.Log("MAIN-xKIzT").OnError(err).Warn("could not connect using normal tls. trying starttls instead...")
+		return smtpConfig.getSMPTClientWithStartTls(host)
+	}
+
+	if err != nil {
+		return nil, caos_errs.ThrowInternal(err, "EMAIL-sl39s", "could not make tls dial")
+	}
+
+	client, err := smtp.NewClient(conn, host)
+	if err != nil {
+		return nil, caos_errs.ThrowInternal(err, "EMAIL-skwi4", "could not create smtp client")
+	}
+	return client, err
+}
+
+func (smtpConfig SMTP) getSMPTClientWithStartTls(host string) (*smtp.Client, error) {
+	client, err := smtpConfig.getSMPTClient()
+	if err != nil {
+		return nil, err
+	}
+
+	if err := client.StartTLS(&tls.Config{
+		ServerName: host,
+	}); err != nil {
+		return nil, caos_errs.ThrowInternal(err, "EMAIL-guvsQ", "could not start tls")
+	}
+	return client, nil
+}
+
+func (smtpConfig SMTP) smtpAuth(client *smtp.Client, host string) error {
+	if !smtpConfig.HasAuth() {
+		return nil
+	}
+	// Auth
+	auth := smtp.PlainAuth("", smtpConfig.User, smtpConfig.Password, host)
+	err := client.Auth(auth)
+	logging.Log("EMAIL-s9kfs").WithField("smtp user", smtpConfig.User).OnError(err).Debug("could not add smtp auth")
+	return err
+}

internal/notification/channels/smtp/config.go

@@ -0,0 +1,18 @@
+package smtp
+
+type EmailConfig struct {
+	SMTP     SMTP
+	Tls      bool
+	From     string
+	FromName string
+}
+
+type SMTP struct {
+	Host     string
+	User     string
+	Password string
+}
+
+func (smtp *SMTP) HasAuth() bool {
+	return smtp.User != "" && smtp.Password != ""
+}