feat: add health check API and handle app configuration warnings

- Removed the old index.html file from the frontend build.
- Integrated a health check query in App component to verify app configuration.
- Display a warning alert if the app is not configured with AZURE_SUBSCRIPTION_ID.
- Updated API module to include health check endpoint.

app-new/backend/src/server.ts

@@ -42,27 +42,32 @@ const makeApp = () => {
   app.use(cors());
   app.use(express.json());
 
-  if (!subscriptionId) {
-    app.get("/api/health", (_req, res) => {
+  const azure = subscriptionId ? new AzureImageService(subscriptionId) : null;
+  const templates = new TemplateService();
+
+  app.get("/api/health", (_req, res) => {
+    if (!subscriptionId) {
       res.status(500).json({
         status: "error",
         message: "Missing AZURE_SUBSCRIPTION_ID"
       });
-    });
+      return;
+    }
 
-    return { app, port };
-  }
-
-  const azure = new AzureImageService(subscriptionId);
-  const templates = new TemplateService();
-
-  app.get("/api/health", (_req, res) => {
     res.json({ status: "ok" });
   });
 
+  const requireAzure = (): AzureImageService => {
+    if (!azure) {
+      throw new Error("Missing AZURE_SUBSCRIPTION_ID");
+    }
+
+    return azure;
+  };
+
   app.get("/api/locations", async (_req, res, next) => {
     try {
-      res.json(await azure.getLocations());
+      res.json(await requireAzure().getLocations());
     } catch (error) {
       next(error);
     }
@@ -71,7 +76,7 @@ const makeApp = () => {
   app.get("/api/publishers", async (req, res, next) => {
     try {
       const { location } = queryLocation.parse(req.query);
-      res.json(await azure.getPublishers(location));
+      res.json(await requireAzure().getPublishers(location));
     } catch (error) {
       next(error);
     }
@@ -80,7 +85,7 @@ const makeApp = () => {
   app.get("/api/offers", async (req, res, next) => {
     try {
       const { location, publisher } = queryOffer.parse(req.query);
-      res.json(await azure.getOffers(location, publisher));
+      res.json(await requireAzure().getOffers(location, publisher));
     } catch (error) {
       next(error);
     }
@@ -89,7 +94,7 @@ const makeApp = () => {
   app.get("/api/skus", async (req, res, next) => {
     try {
       const { location, publisher, offer } = querySku.parse(req.query);
-      res.json(await azure.getSkus(location, publisher, offer));
+      res.json(await requireAzure().getSkus(location, publisher, offer));
     } catch (error) {
       next(error);
     }
@@ -98,7 +103,7 @@ const makeApp = () => {
   app.get("/api/versions", async (req, res, next) => {
     try {
       const { location, publisher, offer, sku } = queryVersion.parse(req.query);
-      res.json(await azure.getVersions(location, publisher, offer, sku));
+      res.json(await requireAzure().getVersions(location, publisher, offer, sku));
     } catch (error) {
       next(error);
     }
@@ -121,7 +126,7 @@ const makeApp = () => {
   app.get("/api/sku-export", async (req, res, next) => {
     try {
       const { location, publisher, offer } = querySku.parse(req.query);
-      const skus = await azure.getSkus(location, publisher, offer);
+      const skus = await requireAzure().getSkus(location, publisher, offer);
       res.json({ rendered: templates.buildSkuExport(skus) });
     } catch (error) {
       next(error);
@@ -151,10 +156,40 @@ const makeApp = () => {
 
 if (require.main === module) {
   const { app, port } = makeApp();
-  app.listen(port, () => {
+  const server = app.listen(port, () => {
     // eslint-disable-next-line no-console
     console.log(`azure-image-chooser listening on ${port}`);
   });
+
+  let shuttingDown = false;
+  const shutdown = (signal: NodeJS.Signals) => {
+    if (shuttingDown) {
+      return;
+    }
+
+    shuttingDown = true;
+    // eslint-disable-next-line no-console
+    console.log(`received ${signal}, shutting down`);
+    server.close((error) => {
+      if (error) {
+        // eslint-disable-next-line no-console
+        console.error("graceful shutdown failed", error);
+        process.exit(1);
+      }
+
+      process.exit(0);
+    });
+
+    // Force-exit if connections do not close in time.
+    setTimeout(() => {
+      // eslint-disable-next-line no-console
+      console.error("shutdown timeout reached, forcing exit");
+      process.exit(1);
+    }, 10_000).unref();
+  };
+
+  process.on("SIGTERM", shutdown);
+  process.on("SIGINT", shutdown);
 }
 
 export { makeApp };