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/fs/channel.go

@@ -0,0 +1,51 @@
+package fs
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/caos/logging"
+
+	caos_errors "github.com/caos/zitadel/internal/errors"
+
+	"github.com/k3a/html2text"
+
+	"github.com/caos/zitadel/internal/notification/channels"
+	"github.com/caos/zitadel/internal/notification/messages"
+)
+
+func InitFSChannel(config FSConfig) (channels.NotificationChannel, error) {
+
+	if err := os.MkdirAll(config.Path, os.ModePerm); err != nil {
+		return nil, err
+	}
+
+	logging.Log("NOTIF-kSvPp").Debug("successfully initialized filesystem email and sms channel")
+
+	return channels.HandleMessageFunc(func(message channels.Message) error {
+
+		fileName := fmt.Sprintf("%d_", time.Now().Unix())
+		content := message.GetContent()
+		switch msg := message.(type) {
+		case *messages.Email:
+			recipients := make([]string, len(msg.Recipients))
+			copy(recipients, msg.Recipients)
+			sort.Strings(recipients)
+			fileName = fileName + "mail_to_" + strings.Join(recipients, "_") + ".html"
+			if config.Compact {
+				content = html2text.HTML2Text(content)
+			}
+		case *messages.SMS:
+			fileName = fileName + "sms_to_" + msg.RecipientPhoneNumber + ".txt"
+		default:
+			return caos_errors.ThrowUnimplementedf(nil, "NOTIF-6f9a1", "filesystem provider doesn't support message type %T", message)
+		}
+
+		return ioutil.WriteFile(filepath.Join(config.Path, fileName), []byte(content), 0666)
+	}), nil
+}

internal/notification/channels/fs/config.go

@@ -0,0 +1,7 @@
+package fs
+
+type FSConfig struct {
+	Enabled bool
+	Path    string
+	Compact bool
+}