feat(example): added an example of packaging a rust app from github (#124)

* better caching when building docker images for app

Reviewed-on: #124
Reviewed-by: johnride <jg@nationtech.io>
Co-authored-by: Willem <wrolleman@nationtech.io>
Co-committed-by: Willem <wrolleman@nationtech.io>

examples/try_rust_webapp/src/main.rs

@@ -0,0 +1,52 @@
+use std::{path::PathBuf, sync::Arc};
+
+use harmony::{
+    inventory::Inventory,
+    modules::{
+        application::{
+            ApplicationScore, RustWebFramework, RustWebapp,
+            features::{ContinuousDelivery, Monitoring},
+        },
+        monitoring::alert_channel::discord_alert_channel::DiscordWebhook,
+    },
+    topology::K8sAnywhereTopology,
+};
+use harmony_types::net::Url;
+
+#[tokio::main]
+async fn main() {
+    let application = Arc::new(RustWebapp {
+        name: "harmony-example-tryrust".to_string(),
+        domain: Url::Url(url::Url::parse("https://tryrust.harmony.example.com").unwrap()),
+        project_root: PathBuf::from("./tryrust.org"),
+        framework: Some(RustWebFramework::Leptos),
+        service_port: 8080,
+    });
+
+    let discord_receiver = DiscordWebhook {
+        name: "test-discord".to_string(),
+        url: Url::Url(url::Url::parse("https://discord.doesnt.exist.com").unwrap()),
+    };
+
+    let app = ApplicationScore {
+        features: vec![
+            Box::new(ContinuousDelivery {
+                application: application.clone(),
+            }),
+            Box::new(Monitoring {
+                application: application.clone(),
+                alert_receiver: vec![Box::new(discord_receiver)],
+            }),
+        ],
+        application,
+    };
+
+    harmony_cli::run(
+        Inventory::autoload(),
+        K8sAnywhereTopology::from_env(),
+        vec![Box::new(app)],
+        None,
+    )
+    .await
+    .unwrap();
+}