Let a label specify its own ntfy topic

References: https://todo.xenrox.net/~xenrox/ntfy-alertmanager/9

README.md

@@ -20,7 +20,7 @@ Furthermore you can take a look at [my deployment].
 
 ntfy-alertmanager has support for setting ntfy [priority], [tags], [icon], [action buttons]
 (which can be used to e.g. create an Alertmanager silence or open the alert's Prometheus URL), [email notifications] and [phone calls].
-Define a decreasing order of labels in the config file and map those labels to tags, priority, an icon or an email address.
+Define a decreasing order of labels in the config file and map those labels to tags, priority, an icon, an email address or an alternative ntfy topic.
 
 - For priority and icon the first found value will be chosen. Settings for "resolved" alerts will take precedence.
 - Tags are added together.

config.scfg

@@ -51,6 +51,7 @@ labels {
     }
 
     instance "example.com" {
+        topic https://ntfy.sh/homeserver
         tags "computer,example"
     }
 }

config/config.go

@@ -58,6 +58,7 @@ type labelConfig struct {
 	Icon         string
 	EmailAddress string
 	Call         string
+	Topic        string
 }
 
 // CacheConfig is the configuration of the cache.
@@ -213,6 +214,13 @@ func parseBlock(block scfg.Block, config *Config) error {
 					}
 				}
 
+				d = labelDir.Children.Get("topic")
+				if d != nil {
+					if err := d.ParseParams(&labelConfig.Topic); err != nil {
+						return err
+					}
+				}
+
 				labels[fmt.Sprintf("%s:%s", labelName, name)] = *labelConfig
 			}
 		}

config/config_test.go

@@ -36,6 +36,7 @@ labels {
 
     instance "example.com" {
         tags "computer,example"
+        topic https://ntfy.sh/homeserver
     }
 }
 
@@ -92,8 +93,10 @@ cache {
 					EmailAddress: "foo@example.com",
 					Call:         "yes",
 				},
-				"severity:info":        {Priority: "1"},
+				"severity:info": {Priority: "1"},
-				"instance:example.com": {Tags: []string{"computer", "example"}},
+				"instance:example.com": {
+					Tags:  []string{"computer", "example"},
+					Topic: "https://ntfy.sh/homeserver"},
 			},
 		},
 		Cache: CacheConfig{

main.go

@@ -69,6 +69,7 @@ type notification struct {
 	fingerprint  string
 	status       string
 	generatorURL string
+	topic        string
 }
 
 type ntfyError struct {
@@ -154,6 +155,10 @@ func (br *bridge) singleAlertNotifications(p *payload) []*notification {
 				n.call = labelConfig.Call
 			}
 
+			if n.topic == "" {
+				n.topic = labelConfig.Topic
+			}
+
 			for _, val := range labelConfig.Tags {
 				if !slices.Contains(tags, val) {
 					tags = append(tags, val)
@@ -264,6 +269,10 @@ func (br *bridge) multiAlertNotification(p *payload) *notification {
 			n.call = labelConfig.Call
 		}
 
+		if n.topic == "" {
+			n.topic = labelConfig.Topic
+		}
+
 		for _, val := range labelConfig.Tags {
 			if !slices.Contains(tags, val) {
 				tags = append(tags, val)
@@ -293,7 +302,12 @@ func (br *bridge) multiAlertNotification(p *payload) *notification {
 }
 
 func (br *bridge) publish(n *notification) error {
-	req, err := http.NewRequest(http.MethodPost, br.cfg.Ntfy.Topic, strings.NewReader(n.body))
+	url := br.cfg.Ntfy.Topic
+	if n.topic != "" {
+		url = n.topic
+	}
+
+	req, err := http.NewRequest(http.MethodPost, url, strings.NewReader(n.body))
 	if err != nil {
 		return err
 	}