Alerting: Add EmbeddedContents as alternative embedding in smtp (#99937)

Adds support for embedding []byte in SmtpClient instead of filenames. This is backwards compatible as it uses a new field EmbeddedContents to add an alternative to the existing EmbeddedFiles which takes filenames.

pkg/services/notifications/email.go

@@ -11,17 +11,24 @@ type AttachedFile struct {
 	Content []byte
 }
 
+// EmbeddedContent struct represents an embedded file.
+type EmbeddedContent struct {
+	Name    string
+	Content []byte
+}
+
 // Message is representation of the email message.
 type Message struct {
-	To            []string
-	SingleEmail   bool
-	From          string
-	Subject       string
-	Body          map[string]string
-	Info          string
-	ReplyTo       []string
-	EmbeddedFiles []string
-	AttachedFiles []*AttachedFile
+	To               []string
+	SingleEmail      bool
+	From             string
+	Subject          string
+	Body             map[string]string
+	Info             string
+	ReplyTo          []string
+	EmbeddedFiles    []string
+	EmbeddedContents []EmbeddedContent
+	AttachedFiles    []*AttachedFile
 }
 
 func setDefaultTemplateData(cfg *setting.Cfg, data map[string]any, u *user.User) {

pkg/services/notifications/mailer.go

@@ -112,14 +112,15 @@ func (ns *NotificationService) buildEmailMessage(cmd *SendEmailCommand) (*Messag
 
 	addr := mail.Address{Name: ns.Cfg.Smtp.FromName, Address: ns.Cfg.Smtp.FromAddress}
 	return &Message{
-		To:            cmd.To,
-		SingleEmail:   cmd.SingleEmail,
-		From:          addr.String(),
-		Subject:       subject,
-		Body:          body,
-		EmbeddedFiles: cmd.EmbeddedFiles,
-		AttachedFiles: buildAttachedFiles(cmd.AttachedFiles),
-		ReplyTo:       cmd.ReplyTo,
+		To:               cmd.To,
+		SingleEmail:      cmd.SingleEmail,
+		From:             addr.String(),
+		Subject:          subject,
+		Body:             body,
+		EmbeddedFiles:    cmd.EmbeddedFiles,
+		EmbeddedContents: cmd.EmbeddedContents,
+		AttachedFiles:    buildAttachedFiles(cmd.AttachedFiles),
+		ReplyTo:          cmd.ReplyTo,
 	}, nil
 }
 

pkg/services/notifications/models.go

@@ -18,15 +18,16 @@ type SendEmailAttachFile struct {
 
 // SendEmailCommand is the command for sending emails
 type SendEmailCommand struct {
-	To            []string
-	SingleEmail   bool
-	Template      string
-	Subject       string
-	Data          map[string]any
-	Info          string
-	ReplyTo       []string
-	EmbeddedFiles []string
-	AttachedFiles []*SendEmailAttachFile
+	To               []string
+	SingleEmail      bool
+	Template         string
+	Subject          string
+	Data             map[string]any
+	Info             string
+	ReplyTo          []string
+	EmbeddedFiles    []string
+	EmbeddedContents []EmbeddedContent
+	AttachedFiles    []*SendEmailAttachFile
 }
 
 // SendEmailCommandSync is the command for sending emails synchronously

pkg/services/notifications/notifications.go

@@ -201,15 +201,16 @@ func __dangerouslyInjectHTML(s string) template.HTML {
 
 func (ns *NotificationService) SendEmailCommandHandlerSync(ctx context.Context, cmd *SendEmailCommandSync) error {
 	message, err := ns.buildEmailMessage(&SendEmailCommand{
-		Data:          cmd.Data,
-		Info:          cmd.Info,
-		Template:      cmd.Template,
-		To:            cmd.To,
-		SingleEmail:   cmd.SingleEmail,
-		EmbeddedFiles: cmd.EmbeddedFiles,
-		AttachedFiles: cmd.AttachedFiles,
-		Subject:       cmd.Subject,
-		ReplyTo:       cmd.ReplyTo,
+		Data:             cmd.Data,
+		Info:             cmd.Info,
+		Template:         cmd.Template,
+		To:               cmd.To,
+		SingleEmail:      cmd.SingleEmail,
+		EmbeddedFiles:    cmd.EmbeddedFiles,
+		EmbeddedContents: cmd.EmbeddedContents,
+		AttachedFiles:    cmd.AttachedFiles,
+		Subject:          cmd.Subject,
+		ReplyTo:          cmd.ReplyTo,
 	})
 	if err != nil {
 		return err

pkg/services/notifications/notifications_test.go

@@ -132,6 +132,31 @@ func TestSendEmailSync(t *testing.T) {
 		require.Equal(t, []byte("text file content"), file.Content)
 	})
 
+	t.Run("When embedding readers to emails", func(t *testing.T) {
+		ns, mailer := createSut(t, bus)
+		cmd := &SendEmailCommandSync{
+			SendEmailCommand: SendEmailCommand{
+				Subject:     "subject",
+				To:          []string{"asdf@grafana.com"},
+				SingleEmail: true,
+				Template:    "welcome_on_signup",
+				EmbeddedContents: []EmbeddedContent{
+					{Name: "embed.jpg", Content: []byte("image content")},
+				},
+			},
+		}
+
+		err := ns.SendEmailCommandHandlerSync(context.Background(), cmd)
+		require.NoError(t, err)
+
+		require.NotEmpty(t, mailer.Sent)
+		sent := mailer.Sent[len(mailer.Sent)-1]
+		require.Len(t, sent.EmbeddedContents, 1)
+		f := sent.EmbeddedContents[0]
+		require.Equal(t, "embed.jpg", f.Name)
+		require.Equal(t, "image content", string(f.Content))
+	})
+
 	t.Run("When SMTP disabled in configuration", func(t *testing.T) {
 		cfg := createSmtpConfig()
 		cfg.Smtp.Enabled = false

pkg/services/notifications/smtp.go

@@ -142,6 +142,13 @@ func (sc *SmtpClient) setFiles(
 		m.Embed(file)
 	}
 
+	for _, file := range msg.EmbeddedContents {
+		m.Embed(file.Name, gomail.SetCopyFunc(func(writer io.Writer) error {
+			_, err := writer.Write(file.Content)
+			return err
+		}))
+	}
+
 	for _, file := range msg.AttachedFiles {
 		file := file
 		m.Attach(file.Name, gomail.SetCopyFunc(func(writer io.Writer) error {