Add endpoint to access internal app IP addresses and ports

src/api.rs

@@ -2,7 +2,7 @@ use poem_openapi::{param::Path, payload::Json, ApiResponse, OpenApi};
 
 use crate::{
     backend::{AppControllerBackend, BackendError},
-    types::{App, AppConfig, AppId, AppStatus},
+    types::{App, AppConfig, AppId, AppStatus, SocketAddr},
 };
 
 pub struct Api<B: AppControllerBackend + 'static>(B);
@@ -85,6 +85,19 @@ enum GetAllAppsResponse {
     InternalError(Json<String>),
 }
 
+#[derive(ApiResponse)]
+enum GetAppAddrResponse {
+    /// The address and port of the app were found successfully.
+    #[oai(status = 200)]
+    Ok(Json<SocketAddr>),
+    /// The app could not be found.
+    #[oai(status = 404)]
+    NotFound,
+    /// The app could not be found because of an internal error.
+    #[oai(status = 500)]
+    InternalError,
+}
+
 #[OpenApi]
 impl<B: AppControllerBackend> Api<B> {
     /// Create new app
@@ -148,4 +161,17 @@ impl<B: AppControllerBackend> Api<B> {
             Err(err) => GetAllAppsResponse::InternalError(Json(err.to_string())),
         }
     }
+
+    /// Get internal app address
+    #[oai(path = "/app/:id/addr", method = "get")]
+    async fn get_app_addr(&self, id: Path<AppId>) -> GetAppAddrResponse {
+        match self.0.get_app_addr(id.0).await {
+            Ok((addr, port)) => GetAppAddrResponse::Ok(Json(SocketAddr {
+                ip: addr.to_string(),
+                port,
+            })),
+            Err(BackendError::NotFound) => GetAppAddrResponse::NotFound,
+            Err(BackendError::InternalError(_)) => GetAppAddrResponse::InternalError,
+        }
+    }
 }

src/backend.rs

@@ -8,7 +8,7 @@ pub use kubernetes::KubernetesBackend;
 #[cfg(test)]
 pub use mock::MockBackend;
 
-use std::future::Future;
+use std::{future::Future, net::IpAddr};
 
 use crate::types::{App, AppConfig, AppId, AppStatus};
 
@@ -34,4 +34,10 @@ pub trait AppControllerBackend: Send + Sync {
 
     /// Get all apps currently managed by the controller.
     fn get_all_apps(&self) -> impl Future<Output = Result<Vec<App>, BackendError>> + Send;
+
+    /// Get the address and port of the app with the given ID.
+    fn get_app_addr(
+        &self,
+        id: AppId,
+    ) -> impl Future<Output = Result<(IpAddr, u16), BackendError>> + Send;
 }

src/backend/kubernetes.rs

@@ -1,4 +1,4 @@
-use std::{collections::BTreeMap, str::FromStr};
+use std::{collections::BTreeMap, net::IpAddr, str::FromStr};
 
 use crate::types::{App, AppConfig, AppId, AppStatus, InteractionModel};
 use k8s_openapi::{
@@ -308,4 +308,32 @@ impl AppControllerBackend for KubernetesBackend {
 
         Ok(apps)
     }
+
+    async fn get_app_addr(&self, id: AppId) -> Result<(IpAddr, u16), BackendError> {
+        let service_api: Api<Service> = Api::default_namespaced(self.client.clone());
+        let list_params = ListParams::default().labels(&format!("app-controller-id={}", id));
+        let list = service_api.list(&list_params).await?;
+
+        // There should be only one service with the given ID.
+        let service = list
+            .items
+            .into_iter()
+            .next()
+            .ok_or(BackendError::NotFound)?;
+
+        // Get the IP address of the service.
+        let raw = service
+            .spec
+            .ok_or(BackendError::InternalError(
+                "Missing spec in service".to_string(),
+            ))?
+            .cluster_ip
+            .ok_or(BackendError::InternalError(
+                "Missing cluster IP in service".to_string(),
+            ))?;
+
+        IpAddr::from_str(&raw)
+            .map(|ip| (ip, 5911))
+            .map_err(|e| BackendError::InternalError(e.to_string()))
+    }
 }

src/backend/mock.rs

@@ -1,5 +1,6 @@
 use std::{
     collections::HashMap,
+    net::IpAddr,
     sync::{
         atomic::{AtomicU64, Ordering},
         RwLock,
@@ -80,4 +81,8 @@ impl AppControllerBackend for MockBackend {
     async fn get_all_apps(&self) -> Result<Vec<App>, BackendError> {
         Ok(self.apps.read().unwrap().values().cloned().collect())
     }
+
+    async fn get_app_addr(&self, _id: AppId) -> Result<(IpAddr, u16), BackendError> {
+        todo!()
+    }
 }

src/types.rs

@@ -45,3 +45,13 @@ pub struct App {
     /// Current status of the app.
     pub config: AppConfig,
 }
+
+pub type IpAddr = String;
+
+/// Address and port of a app.
+#[derive(Debug, Clone, Object)]
+#[oai(read_only_all = true)]
+pub struct SocketAddr {
+    pub ip: IpAddr,
+    pub port: u16,
+}