config: Add cache type

README.md

@@ -96,6 +96,8 @@ alertmanager {
 # When the alert-mode is set to single, ntfy-alertmanager will cache each single alert
 # to avoid sending recurrences.
 cache {
+    # The type of cache that will be used (default is memory).
+    type memory
     # How long messages stay in the cache for
     duration 24h
     # Interval in which the cache is cleaned up

config.go

@@ -16,6 +16,12 @@ const (
 	multi
 )
 
+type cacheType int
+
+const (
+	memory cacheType = iota
+)
+
 type config struct {
 	BaseURL     string
 	HTTPAddress string
@@ -49,6 +55,7 @@ type labelConfig struct {
 }
 
 type cacheConfig struct {
+	Type            cacheType
 	CleanupInterval time.Duration
 	Duration        time.Duration
 }
@@ -77,6 +84,7 @@ func readConfig(path string) (*config, error) {
 	config.LogLevel = "info"
 	config.alertMode = single
 
+	config.cache.Type = memory
 	config.cache.CleanupInterval = time.Hour
 	config.cache.Duration = time.Hour * 24
 
@@ -238,6 +246,21 @@ func readConfig(path string) (*config, error) {
 	cacheDir := cfg.Get("cache")
 
 	if cacheDir != nil {
+		d = cacheDir.Children.Get("type")
+		if d != nil {
+			var cacheType string
+			if err := d.ParseParams(&cacheType); err != nil {
+				return nil, err
+			}
+
+			switch strings.ToLower(cacheType) {
+			case "memory":
+				config.cache.Type = memory
+			default:
+				return nil, fmt.Errorf("cache: illegal type %q", cacheType)
+			}
+		}
+
 		var durationString string
 		d = cacheDir.Children.Get("duration")
 		if d != nil {