Added hangouts chat notification support

docs/notifications.md

@@ -8,6 +8,7 @@ The types of notifications to send are passed via the comma-separated option `--
 - `slack` to send notifications through a Slack webhook
 - `msteams` to send notifications via MSTeams webhook
 - `gotify` to send notifications via Gotify
+- `hangouts` to send notifications via Hangouts Chat webhook
 
 ## Settings
 
@@ -108,3 +109,16 @@ docker run -d \
   -e WATCHTOWER_NOTIFICATION_GOTIFY_TOKEN="SuperSecretToken" \
   containrrr/watchtower
 ```
+
+### Hangouts Chat
+
+To push a notification to a Hangouts Chat channel, create a new [channel webhoook](https://developers.google.com/hangouts/chat/how-tos/webhooks) and set the webhook URL:
+
+```bash
+docker run -d \
+  --name watchtower \
+  -v /var/run/docker.sock:/var/run/docker.sock \
+  -e WATCHTOWER_NOTIFICATIONS=hangouts \
+  -e WATCHTOWER_NOTIFICATION_HANGOUTS_CHAT_WEBHOOK_URL="https://chat.googleapis.com/v1/spaces/XXXXXXX/messages?key=YYYYYYYYY&token=ZZZZZZZZZZ" \
+  containrrr/watchtower
+```

internal/flags/flags.go

@@ -109,7 +109,7 @@ func RegisterNotificationFlags(rootCmd *cobra.Command) {
 		"notifications",
 		"n",
 		viper.GetStringSlice("WATCHTOWER_NOTIFICATIONS"),
-		" notification types to send (valid: email, slack, msteams, gotify)")
+		" notification types to send (valid: email, slack, msteams, gotify, hangouts)")
 
 	flags.StringP(
 		"notifications-level",
@@ -220,6 +220,12 @@ Should only be used for testing.
 		"",
 		viper.GetString("WATCHTOWER_NOTIFICATION_GOTIFY_TOKEN"),
 		"The Gotify Application required to query the Gotify API")
+
+	flags.StringP(
+		"notification-hangouts-url",
+		"",
+		viper.GetString("WATCHTOWER_NOTIFICATION_HANGOUTS_CHAT_WEBHOOK_URL"),
+		"The Hangouts Chat Webhook Channel URL to send notifications to")
 }
 
 // SetDefaults provides default values for environment variables

pkg/notifications/hangouts.go

@@ -0,0 +1,86 @@
+package notifications
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strings"
+
+	t "github.com/containrrr/watchtower/pkg/types"
+	log "github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+)
+
+const (
+	hangoutsType = "hangouts"
+)
+
+type hangoutsTypeNotifier struct {
+	hangoutsURL      string
+	logLevels      []log.Level
+}
+
+func newHangoutsNotifier(c *cobra.Command, acceptedLogLevels []log.Level) t.Notifier {
+	flags := c.PersistentFlags()
+
+	hangoutsURL, _ := flags.GetString("notification-hangouts-url")
+	if len(hangoutsURL) < 1 {
+		log.Fatal("Required argument --notification-hangouts-url(cli) or WATCHTOWER_NOTIFICATION_HANGOUTS_CHAT_WEBHOOK_URL(env) is empty.")
+	} else if !(strings.HasPrefix(hangoutsURL, "http://") || strings.HasPrefix(hangoutsURL, "https://")) {
+		log.Fatal("Hangouts URL must start with \"http://\" or \"https://\"")
+	} else if strings.HasPrefix(hangoutsURL, "http://") {
+		log.Warn("Using an HTTP url for Hangouts is insecure")
+	}
+
+	n := &hangoutsTypeNotifier{
+		hangoutsURL:      hangoutsURL,
+		logLevels:      acceptedLogLevels,
+	}
+
+	log.AddHook(n)
+
+	return n
+}
+
+func (n *hangoutsTypeNotifier) StartNotification() {}
+
+func (n *hangoutsTypeNotifier) SendNotification() {}
+
+func (n *hangoutsTypeNotifier) Levels() []log.Level {
+	return n.logLevels
+}
+
+func (n *hangoutsTypeNotifier) getURL() string {
+	return n.hangoutsURL
+}
+
+func (n *hangoutsTypeNotifier) Fire(entry *log.Entry) error {
+
+	go func() {
+		jsonBody, err := json.Marshal(hangoutsMessage{
+			Text:  "(" + entry.Level.String() + "): " + entry.Message,
+		})
+		if err != nil {
+			fmt.Println("Failed to create JSON body for Hangouts notification: ", err)
+			return
+		}
+
+		jsonBodyBuffer := bytes.NewBuffer([]byte(jsonBody))
+		resp, err := http.Post(n.getURL(), "application/json", jsonBodyBuffer)
+		if err != nil {
+			fmt.Println("Failed to send Hangouts notification: ", err)
+		}
+		defer resp.Body.Close()
+
+		if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+			fmt.Printf("Hangouts notification returned %d HTTP status code", resp.StatusCode)
+		}
+
+	}()
+	return nil
+}
+
+type hangoutsMessage struct {
+	Text  string `json:"text"`
+}

pkg/notifications/notifier.go

@@ -40,6 +40,8 @@ func NewNotifier(c *cobra.Command) *Notifier {
 			tn = newMsTeamsNotifier(c, acceptedLogLevels)
 		case gotifyType:
 			tn = newGotifyNotifier(c, acceptedLogLevels)
+		case hangoutsType:
+			tn = newHangoutsNotifier(c, acceptedLogLevels)
 		default:
 			log.Fatalf("Unknown notification type %q", t)
 		}