feat(server): multi-channel monitor notifications

server/internal/api/channels.go

@@ -0,0 +1,96 @@
+package api
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+	"github.com/mrhid6/vantage/server/internal/models"
+	"github.com/mrhid6/vantage/server/internal/services"
+	"go.mongodb.org/mongo-driver/v2/bson"
+)
+
+func registerChannelRoutes(g *gin.RouterGroup) {
+	g.GET("/channels", listChannels)
+	g.POST("/channels", createChannel)
+	g.PUT("/channels/:id", updateChannel)
+	g.DELETE("/channels/:id", deleteChannel)
+	g.POST("/channels/:id/test", testChannel)
+}
+
+func listChannels(c *gin.Context) {
+	channels, err := services.ListChannels()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusOK, channels)
+}
+
+func createChannel(c *gin.Context) {
+	var ch models.NotificationChannel
+	if err := c.ShouldBindJSON(&ch); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+	if ch.Name == "" || ch.Type == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "name and type are required"})
+		return
+	}
+	created, err := services.CreateChannel(&ch)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusCreated, created)
+}
+
+func updateChannel(c *gin.Context) {
+	var body struct {
+		Name    *string            `json:"name"`
+		Type    *string            `json:"type"`
+		Config  *map[string]string `json:"config"`
+		Enabled *bool              `json:"enabled"`
+	}
+	if err := c.ShouldBindJSON(&body); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+	upd := bson.M{}
+	if body.Name != nil {
+		upd["name"] = *body.Name
+	}
+	if body.Type != nil {
+		upd["type"] = *body.Type
+	}
+	if body.Config != nil {
+		upd["config"] = *body.Config
+	}
+	if body.Enabled != nil {
+		upd["enabled"] = *body.Enabled
+	}
+	if len(upd) == 0 {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "no fields to update"})
+		return
+	}
+	if err := services.UpdateChannel(c.Param("id"), upd); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	c.Status(http.StatusNoContent)
+}
+
+func deleteChannel(c *gin.Context) {
+	if err := services.DeleteChannel(c.Param("id")); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	c.Status(http.StatusNoContent)
+}
+
+func testChannel(c *gin.Context) {
+	if err := services.TestChannel(c.Param("id")); err != nil {
+		c.JSON(http.StatusBadGateway, gin.H{"error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"status": "sent"})
+}

server/internal/api/handlers.go

@@ -81,6 +81,7 @@ func RegisterRoutes(r *gin.Engine) {
 
 		registerWorkflowRoutes(apiGroup)
 		registerMonitorRoutes(apiGroup)
+		registerChannelRoutes(apiGroup)
 	}
 }
 

server/internal/models/channel.go

@@ -0,0 +1,29 @@
+package models
+
+import (
+	"time"
+
+	"go.mongodb.org/mongo-driver/v2/bson"
+)
+
+// Notification channel types.
+const (
+	ChannelWebhook  = "webhook"
+	ChannelSMTP     = "smtp"
+	ChannelDiscord  = "discord"
+	ChannelSlack    = "slack"
+	ChannelTelegram = "telegram"
+)
+
+// NotificationChannel is an outbound alert destination. Config holds
+// type-specific settings (e.g. url; or smtp host/port/username/password/from/to;
+// or telegram token/chat_id).
+type NotificationChannel struct {
+	ID        bson.ObjectID     `bson:"_id,omitempty" json:"_id,omitempty"`
+	ChannelID string            `bson:"channel_id" json:"channel_id"`
+	Name      string            `bson:"name" json:"name"`
+	Type      string            `bson:"type" json:"type"`
+	Config    map[string]string `bson:"config" json:"config"`
+	Enabled   bool              `bson:"enabled" json:"enabled"`
+	CreatedAt time.Time         `bson:"created_at" json:"created_at"`
+}

server/internal/notify/dispatch.go

@@ -0,0 +1,64 @@
+// Package notify formats and delivers monitor state-change alerts to
+// notification channels. It depends only on models so services can call it
+// without an import cycle.
+package notify
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/mrhid6/vantage/server/internal/models"
+)
+
+// Event describes a monitor state transition worth alerting on.
+type Event struct {
+	MonitorName string
+	Type        string
+	OldStatus   string
+	NewStatus   string
+	Message     string
+	Time        time.Time
+}
+
+// title is a short one-line summary used by the text-based channels.
+func (e Event) title() string {
+	verb := "recovered"
+	if e.NewStatus == models.StatusDown {
+		verb = "is DOWN"
+	}
+	s := fmt.Sprintf("[Vantage] %s (%s) %s", e.MonitorName, e.Type, verb)
+	if e.Message != "" {
+		s += ": " + e.Message
+	}
+	return s
+}
+
+// Dispatch delivers ev to a single channel, formatting per channel type.
+func Dispatch(ch models.NotificationChannel, ev Event) error {
+	switch ch.Type {
+	case models.ChannelWebhook:
+		return dispatchWebhook(ch, ev)
+	case models.ChannelDiscord:
+		return dispatchDiscord(ch, ev)
+	case models.ChannelSlack:
+		return dispatchSlack(ch, ev)
+	case models.ChannelTelegram:
+		return dispatchTelegram(ch, ev)
+	case models.ChannelSMTP:
+		return dispatchSMTP(ch, ev)
+	default:
+		return fmt.Errorf("unknown channel type: %s", ch.Type)
+	}
+}
+
+// Test delivers a synthetic event so users can verify a channel's configuration.
+func Test(ch models.NotificationChannel) error {
+	return Dispatch(ch, Event{
+		MonitorName: "Test monitor",
+		Type:        "http",
+		OldStatus:   models.StatusUp,
+		NewStatus:   models.StatusDown,
+		Message:     "this is a test alert from Vantage",
+		Time:        time.Now(),
+	})
+}

server/internal/notify/http.go

@@ -0,0 +1,71 @@
+package notify
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/mrhid6/vantage/server/internal/models"
+)
+
+var httpClient = &http.Client{Timeout: 10 * time.Second}
+
+func postJSON(target string, payload any) error {
+	body, err := json.Marshal(payload)
+	if err != nil {
+		return err
+	}
+	resp, err := httpClient.Post(target, "application/json", bytes.NewReader(body))
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode >= 300 {
+		return fmt.Errorf("HTTP %d from %s", resp.StatusCode, target)
+	}
+	return nil
+}
+
+// dispatchWebhook posts the full event as JSON to a user-supplied URL.
+func dispatchWebhook(ch models.NotificationChannel, ev Event) error {
+	target := ch.Config["url"]
+	if target == "" {
+		return fmt.Errorf("webhook: missing url")
+	}
+	return postJSON(target, map[string]any{
+		"monitor":    ev.MonitorName,
+		"type":       ev.Type,
+		"old_status": ev.OldStatus,
+		"new_status": ev.NewStatus,
+		"message":    ev.Message,
+		"time":       ev.Time.Format(time.RFC3339),
+	})
+}
+
+func dispatchDiscord(ch models.NotificationChannel, ev Event) error {
+	target := ch.Config["url"]
+	if target == "" {
+		return fmt.Errorf("discord: missing url")
+	}
+	return postJSON(target, map[string]string{"content": ev.title()})
+}
+
+func dispatchSlack(ch models.NotificationChannel, ev Event) error {
+	target := ch.Config["url"]
+	if target == "" {
+		return fmt.Errorf("slack: missing url")
+	}
+	return postJSON(target, map[string]string{"text": ev.title()})
+}
+
+func dispatchTelegram(ch models.NotificationChannel, ev Event) error {
+	token := ch.Config["token"]
+	chatID := ch.Config["chat_id"]
+	if token == "" || chatID == "" {
+		return fmt.Errorf("telegram: missing token or chat_id")
+	}
+	api := fmt.Sprintf("https://api.telegram.org/bot%s/sendMessage", token)
+	return postJSON(api, map[string]string{"chat_id": chatID, "text": ev.title()})
+}

server/internal/notify/smtp.go

@@ -0,0 +1,45 @@
+package notify
+
+import (
+	"fmt"
+	"net/smtp"
+	"strings"
+
+	"github.com/mrhid6/vantage/server/internal/models"
+)
+
+// dispatchSMTP sends the alert as a plain-text email. Config keys: host, port,
+// username, password, from, to. Auth is skipped when username is empty.
+func dispatchSMTP(ch models.NotificationChannel, ev Event) error {
+	host := ch.Config["host"]
+	port := ch.Config["port"]
+	from := ch.Config["from"]
+	to := ch.Config["to"]
+	if host == "" || port == "" || from == "" || to == "" {
+		return fmt.Errorf("smtp: missing host/port/from/to")
+	}
+
+	title := ev.title()
+	msg := strings.Join([]string{
+		"From: " + from,
+		"To: " + to,
+		"Subject: " + title,
+		"",
+		title,
+		"",
+		"Monitor: " + ev.MonitorName,
+		"Status: " + ev.OldStatus + " -> " + ev.NewStatus,
+		"Time: " + ev.Time.String(),
+	}, "\r\n")
+
+	var auth smtp.Auth
+	if user := ch.Config["username"]; user != "" {
+		auth = smtp.PlainAuth("", user, ch.Config["password"], host)
+	}
+	addr := host + ":" + port
+	recipients := strings.Split(to, ",")
+	for i := range recipients {
+		recipients[i] = strings.TrimSpace(recipients[i])
+	}
+	return smtp.SendMail(addr, auth, from, recipients, []byte(msg))
+}

server/internal/services/channels.go

@@ -0,0 +1,100 @@
+package services
+
+import (
+	"errors"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/mrhid6/vantage/server/internal/db"
+	"github.com/mrhid6/vantage/server/internal/models"
+	"github.com/mrhid6/vantage/server/internal/notify"
+	"go.mongodb.org/mongo-driver/v2/bson"
+	"go.mongodb.org/mongo-driver/v2/mongo"
+	"go.mongodb.org/mongo-driver/v2/mongo/options"
+)
+
+func ListChannels() ([]models.NotificationChannel, error) {
+	ctx, cancel := monCtx()
+	defer cancel()
+	cur, err := db.Col("notification_channels").Find(ctx, bson.M{}, options.Find().SetSort(bson.M{"created_at": 1}))
+	if err != nil {
+		return nil, err
+	}
+	var out []models.NotificationChannel
+	if err := cur.All(ctx, &out); err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func GetChannel(channelID string) (*models.NotificationChannel, error) {
+	ctx, cancel := monCtx()
+	defer cancel()
+	var ch models.NotificationChannel
+	err := db.Col("notification_channels").FindOne(ctx, bson.M{"channel_id": channelID}).Decode(&ch)
+	if errors.Is(err, mongo.ErrNoDocuments) {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	return &ch, nil
+}
+
+// GetChannels loads multiple channels by ID, skipping any not found.
+func GetChannels(channelIDs []string) ([]models.NotificationChannel, error) {
+	if len(channelIDs) == 0 {
+		return nil, nil
+	}
+	ctx, cancel := monCtx()
+	defer cancel()
+	cur, err := db.Col("notification_channels").Find(ctx, bson.M{"channel_id": bson.M{"$in": channelIDs}})
+	if err != nil {
+		return nil, err
+	}
+	var out []models.NotificationChannel
+	if err := cur.All(ctx, &out); err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func CreateChannel(ch *models.NotificationChannel) (*models.NotificationChannel, error) {
+	ctx, cancel := monCtx()
+	defer cancel()
+	ch.ChannelID = uuid.NewString()
+	ch.CreatedAt = time.Now()
+	if ch.Config == nil {
+		ch.Config = map[string]string{}
+	}
+	if _, err := db.Col("notification_channels").InsertOne(ctx, ch); err != nil {
+		return nil, err
+	}
+	return ch, nil
+}
+
+func UpdateChannel(channelID string, upd bson.M) error {
+	ctx, cancel := monCtx()
+	defer cancel()
+	_, err := db.Col("notification_channels").UpdateOne(ctx, bson.M{"channel_id": channelID}, bson.M{"$set": upd})
+	return err
+}
+
+func DeleteChannel(channelID string) error {
+	ctx, cancel := monCtx()
+	defer cancel()
+	_, err := db.Col("notification_channels").DeleteOne(ctx, bson.M{"channel_id": channelID})
+	return err
+}
+
+// TestChannel sends a synthetic alert to verify configuration.
+func TestChannel(channelID string) error {
+	ch, err := GetChannel(channelID)
+	if err != nil {
+		return err
+	}
+	if ch == nil {
+		return errors.New("channel not found")
+	}
+	return notify.Test(*ch)
+}

server/internal/services/monitors.go

@@ -3,12 +3,14 @@ package services
 import (
 	"context"
 	"errors"
+	"log"
 	"time"
 
 	"github.com/google/uuid"
 	"github.com/mrhid6/vantage/server/internal/checker"
 	"github.com/mrhid6/vantage/server/internal/db"
 	"github.com/mrhid6/vantage/server/internal/models"
+	"github.com/mrhid6/vantage/server/internal/notify"
 	"go.mongodb.org/mongo-driver/v2/bson"
 	"go.mongodb.org/mongo-driver/v2/mongo"
 	"go.mongodb.org/mongo-driver/v2/mongo/options"
@@ -233,9 +235,35 @@ func IngestResult(monitorID string, res checker.Result) error {
 	return nil
 }
 
-// notifyTransition dispatches notifications on an up<->down transition. Wired up
-// in Task 13 (P3); a no-op until then.
+// notifyTransition dispatches notifications on an up<->down transition to each
+// enabled channel bound to the monitor. Deliveries run in the background;
+// failures are logged, not fatal.
 func notifyTransition(m *models.Monitor, newStatus, message string) {
-	// TODO(P3): resolve m.ChannelIDs and dispatch via the notify package,
-	// honouring a resend interval tracked on state.last_notified_at.
+	if len(m.ChannelIDs) == 0 {
+		return
+	}
+	channels, err := GetChannels(m.ChannelIDs)
+	if err != nil {
+		log.Printf("notify: load channels for %s: %v", m.MonitorID, err)
+		return
+	}
+	ev := notify.Event{
+		MonitorName: m.Name,
+		Type:        m.Type,
+		OldStatus:   m.State.Status,
+		NewStatus:   newStatus,
+		Message:     message,
+		Time:        time.Now(),
+	}
+	for _, ch := range channels {
+		if !ch.Enabled {
+			continue
+		}
+		go func(c models.NotificationChannel) {
+			if err := notify.Dispatch(c, ev); err != nil {
+				log.Printf("notify: dispatch to %s (%s): %v", c.Name, c.Type, err)
+			}
+		}(ch)
+	}
+	_ = UpdateMonitor(m.MonitorID, bson.M{"state.last_notified_at": time.Now()})
 }