feat(alerting): add option to disable message caching in ntfy provider

https://docs.ntfy.sh/publish/#message-caching

README.md

@@ -953,6 +953,7 @@ endpoints:
 | `alerting.ntfy.click`         | Website opened when notification is clicked                                                                                   | `""`              |
 | `alerting.ntfy.priority`      | The priority of the alert                                                                                                     | `3`               |
 | `alerting.ntfy.firebase`      | Whether messages should be delivered via firebase. [ntfy.sh defaults to true](https://docs.ntfy.sh/publish/#disable-firebase) | `nil`             |
+| `alerting.ntfy.cache`         | Whether message should be cached server side. [ntfy.sh defaults to true](https://docs.ntfy.sh/publish/#message-caching)       | `nil`             |
 | `alerting.ntfy.default-alert` | Default alert configuration. <br />See [Setting a default alert](#setting-a-default-alert)                                    | N/A               |
 
 [ntfy](https://github.com/binwiederhier/ntfy) is an amazing project that allows you to subscribe to desktop

alerting/provider/ntfy/ntfy.go

@@ -28,6 +28,7 @@ type AlertProvider struct {
 	Email    string `yaml:"email,omitempty"`    // Defaults to ""
 	Click    string `yaml:"click,omitempty"`    // Defaults to ""
 	Firebase *bool  `yaml:"firebase,omitempty"` // Defaults to nil
+	Cache    *bool  `yaml:"cache,omitempty"`    // Defaults to nil
 
 	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
 	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
@@ -62,6 +63,9 @@ func (provider *AlertProvider) Send(ep *endpoint.Endpoint, alert *alert.Alert, r
 	if provider.Firebase != nil && !*provider.Firebase {
 		request.Header.Set("Firebase", "no")
 	}
+	if provider.Cache != nil && !*provider.Cache {
+		request.Header.Set("Cache", "no")
+	}
 	response, err := client.GetHTTPClient(nil).Do(request)
 	if err != nil {
 		return err