feat: Alerting module architecture to make it easy to use and extensible by external crates

Co-authored-by: Jean-Gabriel Gill-Couture <jg@nationtech.io>
Reviewed-on: #61
Reviewed-by: johnride <jg@nationtech.io>
Co-authored-by: Willem <wrolleman@nationtech.io>
Co-committed-by: Willem <wrolleman@nationtech.io>

adr/010-monitoring-alerting/architecture.rs

@@ -0,0 +1,73 @@
+pub trait MonitoringSystem {}
+
+// 1. Modified AlertReceiver trait:
+//    - Removed the problematic `clone` method.
+//    - Added `box_clone` which returns a Box<dyn AlertReceiver>.
+pub trait AlertReceiver {
+    type M: MonitoringSystem;
+    fn install(&self, sender: &Self::M) -> Result<(), String>;
+    // This method allows concrete types to clone themselves into a Box<dyn AlertReceiver>
+    fn box_clone(&self) -> Box<dyn AlertReceiver<M = Self::M>>;
+}
+#[derive(Clone)]
+struct Prometheus{}
+impl MonitoringSystem for Prometheus {}
+
+#[derive(Clone)] // Keep derive(Clone) for DiscordWebhook itself
+struct DiscordWebhook{}
+
+impl AlertReceiver for DiscordWebhook {
+    type M = Prometheus;
+    fn install(&self, sender: &Self::M) -> Result<(), String> {
+        // Placeholder for actual installation logic
+        println!("DiscordWebhook installed for Prometheus monitoring.");
+        Ok(())
+    }
+    // 2. Implement `box_clone` for DiscordWebhook:
+    //    This uses the derived `Clone` for DiscordWebhook to create a new boxed instance.
+    fn box_clone(&self) -> Box<dyn AlertReceiver<M = Self::M>> {
+        Box::new(self.clone())
+    }
+}
+
+// 3. Implement `std::clone::Clone` for `Box<dyn AlertReceiver<M= M>>`:
+//    This allows `Box<dyn AlertReceiver>` to be cloned.
+//    The `+ 'static` lifetime bound is often necessary for trait objects stored in collections,
+//    ensuring they live long enough.
+impl<M: MonitoringSystem + 'static> Clone for Box<dyn AlertReceiver<M= M>> {
+    fn clone(&self) -> Self {
+        self.box_clone() // Call the custom `box_clone` method
+    }
+}
+
+// MonitoringConfig can now derive Clone because its `receivers` field
+// (Vec<Box<dyn AlertReceiver<M = M>>>) is now cloneable.
+#[derive(Clone)]
+struct MonitoringConfig <M: MonitoringSystem + 'static>{
+    receivers: Vec<Box<dyn AlertReceiver<M = M>>>
+}
+
+// Example usage to demonstrate compilation and functionality
+fn main() {
+    let prometheus_instance = Prometheus{};
+    let discord_webhook_instance = DiscordWebhook{};
+
+    let mut config = MonitoringConfig {
+        receivers: Vec::new()
+    };
+
+    // Create a boxed alert receiver
+    let boxed_receiver: Box<dyn AlertReceiver<M = Prometheus>> = Box::new(discord_webhook_instance);
+    config.receivers.push(boxed_receiver);
+
+    // Clone the config, which will now correctly clone the boxed receiver
+    let cloned_config = config.clone();
+
+    println!("Original config has {} receivers.", config.receivers.len());
+    println!("Cloned config has {} receivers.", cloned_config.receivers.len());
+
+    // Example of using the installed receiver
+    if let Some(receiver) = config.receivers.get(0) {
+        let _ = receiver.install(&prometheus_instance);
+    }
+}