config: Add required settings for silencing alerts

README.md

@@ -25,6 +25,9 @@ decreasing order of labels in the config file and map those labels to tags or pr
 Example:
 
 ```
+# Public facing base URL of the service (e.g. https://ntfy-alertmanager.xenrox.net)
+# This setting is required for the "Silence" feature.
+base-url https://ntfy-alertmanager.xenrox.net
 # http listen address
 http-address :8080
 # Log level (either debug, info, warning, error)
@@ -61,6 +64,14 @@ ntfy {
     password pass
 }
 
+alertmanager {
+    # If set, the ntfy message will contain a "Silence" button, which can be used
+    # to create a silence via the Alertmanager API. Because of limitations in ntfy,
+    # the request will be proxied through ntfy-alertmanager. Therefore ntfy-alertmanager
+    # needs to be exposed to external network requests and base-url has to be set.
+    silence-duration 24h
+}
+
 # When the alert-mode is set to single, ntfy-alertmanager will cache each single alert
 # to avoid sending recurrences.
 cache {

config.go

@@ -16,6 +16,7 @@ const (
 )
 
 type config struct {
+	BaseURL     string
 	HTTPAddress string
 	LogLevel    string
 	alertMode   alertMode
@@ -24,6 +25,7 @@ type config struct {
 	ntfy        ntfyConfig
 	labels      labels
 	cache       cacheConfig
+	am          alertmanagerConfig
 }
 
 type ntfyConfig struct {
@@ -47,6 +49,10 @@ type cacheConfig struct {
 	Duration        time.Duration
 }
 
+type alertmanagerConfig struct {
+	SilenceDuration time.Duration
+}
+
 func readConfig(path string) (*config, error) {
 	cfg, err := scfg.Load(path)
 	if err != nil {
@@ -76,6 +82,13 @@ func readConfig(path string) (*config, error) {
 		}
 	}
 
+	d = cfg.Get("base-url")
+	if d != nil {
+		if err := d.ParseParams(&config.BaseURL); err != nil {
+			return nil, err
+		}
+	}
+
 	d = cfg.Get("alert-mode")
 	if d != nil {
 		var mode string
@@ -216,5 +229,24 @@ func readConfig(path string) (*config, error) {
 		}
 	}
 
+	amDir := cfg.Get("alertmanager")
+
+	if amDir != nil {
+		var durationString string
+		d = amDir.Children.Get("silence-duration")
+		if d != nil {
+			if err := d.ParseParams(&durationString); err != nil {
+				return nil, err
+			}
+
+			duration, err := time.ParseDuration(durationString)
+			if err != nil {
+				return nil, err
+			}
+
+			config.am.SilenceDuration = duration
+		}
+	}
+
 	return config, nil
 }

config_test.go

@@ -10,6 +10,9 @@ import (
 
 func TestReadConfig(t *testing.T) {
 	configContent := `
+# Public facing base URL of the service (e.g. https://ntfy-alertmanager.xenrox.net)
+# This setting is required for the "Silence" feature.
+base-url https://ntfy-alertmanager.xenrox.net
 # http listen address
 http-address :8080
 # Log level (either debug, info, warning, error)
@@ -46,6 +49,14 @@ ntfy {
     password pass
 }
 
+alertmanager {
+    # If set, the ntfy message will contain a "Silence" button, which can be used
+    # to create a silence via the Alertmanager API. Because of limitations in ntfy,
+    # the request will be proxied through ntfy-alertmanager. Therefore ntfy-alertmanager
+    # needs to be exposed to external network requests and base-url has to be set.
+    silence-duration 24h
+}
+
 # When the alert-mode is set to single, ntfy-alertmanager will cache each single alert
 # to avoid sending recurrences.
 cache {
@@ -57,8 +68,13 @@ cache {
 `
 
 	expectedCfg := &config{
-		HTTPAddress: ":8080", LogLevel: "info", alertMode: multi, User: "webhookUser", Password: "webhookPass",
-		ntfy: ntfyConfig{Topic: "https://ntfy.sh/alertmanager-alerts", User: "user", Password: "pass"},
+		BaseURL:     "https://ntfy-alertmanager.xenrox.net",
+		HTTPAddress: ":8080",
+		LogLevel:    "info",
+		alertMode:   multi,
+		User:        "webhookUser",
+		Password:    "webhookPass",
+		ntfy:        ntfyConfig{Topic: "https://ntfy.sh/alertmanager-alerts", User: "user", Password: "pass"},
 		labels: labels{Order: []string{"severity", "instance"},
 			Label: map[string]labelConfig{
 				"severity:critical":    {Priority: "5", Tags: []string{"rotating_light"}},
@@ -67,6 +83,7 @@ cache {
 			},
 		},
 		cache: cacheConfig{CleanupInterval: time.Hour, Duration: 48 * time.Hour},
+		am:    alertmanagerConfig{SilenceDuration: time.Hour * 24},
 	}
 
 	configPath := filepath.Join(t.TempDir(), "config")