Added alive endpoint

CHANGELOG.md

@@ -1,5 +1,9 @@
 Note: Numbers like (#123) point to closed Pull Requests on the fractal-vizarr-viewer repository.
 
+# Unreleased
+
+* Added `/alive` endpoint (\#55);
+
 # 0.3.0
 
 * Retrieved complete list of allowed viewer paths directly from fractal-server: (\#53);

README.md

@@ -203,6 +203,10 @@ The output is located in the `dist` folder.
 
 Then go back to fractal-vizarr-viewer folder and run `npm run start` to start the project. The server will start on port 3000.
 
+### Alive endpoint
+
+It is possible to use the `/alive` endpoint to check if the service is up and running and retrieve its version.
+
 ## Docker setup
 
 The following script can be used to build and start a docker image for testing:

src/alive.ts

@@ -0,0 +1,31 @@
+import type { Request, Response } from "express";
+import { createRequire } from "module";
+import { getConfig } from "./config.js";
+import { getLogger } from "./logger.js";
+
+const config = getConfig();
+const logger = getLogger();
+
+export async function aliveEndpoint(_: Request, res: Response) {
+
+  // reading version from package.json
+  const require = createRequire(import.meta.url);
+  const { version } = require("../package.json");
+
+  // retrieving server status
+  let fractal_server_alive = false;
+  let fractal_server_version: string | null = null;
+
+  try {
+    const response = await fetch(`${config.fractalServerUrl}/api/alive/`);
+    if (response.ok) {
+      const { alive, version } = await response.json();
+      fractal_server_alive = alive;
+      fractal_server_version = version;
+    }
+  } catch {
+    logger.error("Error reading fractal-server alive endpoint");
+  }
+
+  res.json({ alive: true, version, fractal_server_alive, fractal_server_version }).end();
+}

src/app.ts

@@ -3,6 +3,7 @@ import { getLogger } from "./logger.js";
 import { getConfig } from "./config.js";
 import { serveZarrData } from "./data.js";
 import { getAuthorizer } from "./authorizer.js";
+import { aliveEndpoint } from "./alive.js";
 
 const config = getConfig();
 const logger = getLogger();
@@ -23,6 +24,11 @@ app.use(`${config.basePath}data`, async function (req, res) {
   await serveZarrData(authorizer, req, res);
 });
 
+// Alive endpoint
+app.use(`${config.basePath}alive`, async function (req, res) {
+  await aliveEndpoint(req, res);
+});
+
 // Serving Vizarr static files
 app.use(`${config.basePath}`, express.static(config.vizarrStaticFilesPath));