Add discord notification service. Close #143

README.md

@@ -189,7 +189,9 @@ Watchtower can send notifications when containers are updated. Notifications are
 The types of notifications to send are passed via the comma-separated option `--notifications` (or corresponding environment variable `WATCHTOWER_NOTIFICATIONS`), which has the following valid values:
 
 * `email` to send notifications via e-mail
+* `discord` to send notifications into Discord channel
 
+### Email
 To receive notifications by email, the following command-line options, or their corresponding environment variables, can be set:
 
 * `--notification-email-from` (env. `WATCHTOWER_NOTIFICATION_EMAIL_FROM`): The e-mail address from which notifications will be sent.
@@ -214,3 +216,11 @@ docker run -d \
   v2tec/watchtower
 ```
 
+### Discord
+To send notifications into Discord channel, the following command-line options, or their corresponding environment variables, can be set:
+
+* `--notification-discord-webhook` (env. `WATCHTOWER_NOTIFICATION_DISCORD_WEBHOOK`): Webhook URL configured in Discord.
+
+[Checkout how to add webhook for channel](https://support.discordapp.com/hc/en-us/articles/228383668)
+
+

main.go

@@ -91,42 +91,47 @@ func main() {
 			Usage: "enable debug mode with verbose logging",
 		},
 		cli.StringSliceFlag{
-			Name: "notifications",
+			Name:   "notifications",
-			Value: &cli.StringSlice{},
+			Value:  &cli.StringSlice{},
-			Usage: "notification types to send (valid: email)",
+			Usage:  "notification types to send (valid: email, discord)",
 			EnvVar: "WATCHTOWER_NOTIFICATIONS",
 		},
 		cli.StringFlag{
-			Name: "notification-email-from",
+			Name:   "notification-email-from",
-			Usage: "Address to send notification e-mails from",
+			Usage:  "Address to send notification e-mails from",
 			EnvVar: "WATCHTOWER_NOTIFICATION_EMAIL_FROM",
 		},
 		cli.StringFlag{
-			Name: "notification-email-to",
+			Name:   "notification-email-to",
-			Usage: "Address to send notification e-mails to",
+			Usage:  "Address to send notification e-mails to",
 			EnvVar: "WATCHTOWER_NOTIFICATION_EMAIL_TO",
 		},
 		cli.StringFlag{
-			Name: "notification-email-server",
+			Name:   "notification-email-server",
-			Usage: "SMTP server to send notification e-mails through",
+			Usage:  "SMTP server to send notification e-mails through",
 			EnvVar: "WATCHTOWER_NOTIFICATION_EMAIL_SERVER",
 		},
 		cli.IntFlag{
-			Name: "notification-email-server-port",
+			Name:   "notification-email-server-port",
-			Usage: "SMTP server port to send notification e-mails through",
+			Usage:  "SMTP server port to send notification e-mails through",
 			Value:  25,
 			EnvVar: "WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PORT",
 		},
 		cli.StringFlag{
-			Name: "notification-email-server-user",
+			Name:   "notification-email-server-user",
-			Usage: "SMTP server user for sending notifications",
+			Usage:  "SMTP server user for sending notifications",
 			EnvVar: "WATCHTOWER_NOTIFICATION_EMAIL_SERVER_USER",
 		},
 		cli.StringFlag{
-			Name: "notification-email-server-password",
+			Name:   "notification-email-server-password",
-			Usage: "SMTP server password for sending notifications",
+			Usage:  "SMTP server password for sending notifications",
 			EnvVar: "WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PASSWORD",
 		},
+		cli.StringFlag{
+			Name:   "notification-discord-webhook",
+			Usage:  "Discord webhook url for sending notifications",
+			EnvVar: "WATCHTOWER_NOTIFICATION_DISCORD_WEBHOOK",
+		},
 	}
 
 	if err := app.Run(os.Args); err != nil {
@@ -180,7 +185,7 @@ func start(c *cli.Context) error {
 		scheduleSpec,
 		func() {
 			select {
-			case v := <- tryLockSem:
+			case v := <-tryLockSem:
 				defer func() { tryLockSem <- v }()
 				notifier.StartNotification()
 				if err := actions.Update(client, names, cleanup, noRestart); err != nil {

notifications/discord.go

@@ -0,0 +1,96 @@
+package notifications
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+
+	log "github.com/Sirupsen/logrus"
+	"github.com/urfave/cli"
+)
+
+const (
+	discordType = "discord"
+)
+
+type discordTypeNotifier struct {
+	WebhookURL string
+	entries    []*log.Entry
+}
+
+func newDiscordNotifier(c *cli.Context) typeNotifier {
+	n := &discordTypeNotifier{
+		WebhookURL: c.GlobalString("notification-discord-webhook"),
+	}
+
+	log.AddHook(n)
+
+	return n
+}
+
+func (n *discordTypeNotifier) sendEntries(entries []*log.Entry) {
+	// Do the sending in a separate goroutine so we don't block the main process.
+	message := ""
+	for _, entry := range entries {
+		message += entry.Time.Format("2006-01-02 15:04:05") + " (" + entry.Level.String() + "): " + entry.Message + "\r\n"
+	}
+
+	go func() {
+		webhookBody := discordWebhookBody{Content: message}
+		jsonBody, err := json.Marshal(webhookBody)
+		if err != nil {
+			fmt.Println("Failed to build JSON body for Discord notificattion: ", err)
+			return
+		}
+
+		resp, err := http.Post(n.WebhookURL, "application/json", bytes.NewBuffer([]byte(jsonBody)))
+		if err != nil {
+			fmt.Println("Failed to send Discord notificattion: ", err)
+		}
+
+		defer resp.Body.Close()
+
+		if resp.StatusCode < 200 || resp.StatusCode > 299 {
+			fmt.Println("Failed to send Discord notificattion. HTTP RESPONSE STATUS: ", resp.StatusCode)
+		}
+	}()
+}
+
+func (n *discordTypeNotifier) StartNotification() {
+	if n.entries == nil {
+		n.entries = make([]*log.Entry, 0, 10)
+	}
+}
+
+func (n *discordTypeNotifier) SendNotification() {
+	if n.entries != nil && len(n.entries) != 0 {
+		n.sendEntries(n.entries)
+	}
+	n.entries = nil
+}
+
+func (n *discordTypeNotifier) Levels() []log.Level {
+	// TODO: Make this configurable.
+	return []log.Level{
+		log.PanicLevel,
+		log.FatalLevel,
+		log.ErrorLevel,
+		log.WarnLevel,
+		log.InfoLevel,
+	}
+}
+
+func (n *discordTypeNotifier) Fire(entry *log.Entry) error {
+	if n.entries != nil {
+		n.entries = append(n.entries, entry)
+	} else {
+		// Log output generated outside a cycle is sent immediately.
+		n.sendEntries([]*log.Entry{entry})
+	}
+	return nil
+}
+
+type discordWebhookBody struct {
+	Content string `json:"content"`
+}

notifications/notifier.go

@@ -26,6 +26,8 @@ func NewNotifier(c *cli.Context) *Notifier {
 		switch t {
 		case emailType:
 			tn = newEmailNotifier(c)
+		case discordType:
+			tn = newDiscordNotifier(c)
 		default:
 			log.Fatalf("Unknown notification type %q", t)
 		}