diff --git a/keyserver/src/keyserver.js b/keyserver/src/keyserver.js
--- a/keyserver/src/keyserver.js
+++ b/keyserver/src/keyserver.js
@@ -95,8 +95,29 @@
   const areEndpointMetricsEnabled =
     process.env.KEYSERVER_ENDPOINT_METRICS_ENABLED;
 
+  const listenAddress = (() => {
+    if (process.env.COMM_LISTEN_ADDR) {
+      return process.env.COMM_LISTEN_ADDR;
+    } else if (process.env.NODE_ENV === 'development') {
+      return undefined;
+    } else {
+      return 'localhost';
+    }
+  })();
+
   if (cluster.isMaster) {
     if (isPrimaryNode) {
+      const app = express();
+      app.use(express.json({ limit: '250mb' }));
+      app.get('/health', (req: $Request, res: $Response) => {
+        res.send('OK');
+      });
+
+      const server = app.listen(
+        parseInt(process.env.PORT, 10) || 3000,
+        listenAddress,
+      );
+
       const didMigrationsSucceed: boolean = await migrate();
       if (!didMigrationsSucceed) {
         // The following line uses exit code 2 to ensure nodemon exits
@@ -104,6 +125,18 @@
         // in https://github.com/remy/nodemon/issues/751
         process.exit(2);
       }
+
+      if (server) {
+        await new Promise((resolve, reject) => {
+          server.close(err => {
+            if (err) {
+              reject(err);
+            } else {
+              resolve();
+            }
+          });
+        });
+      }
     }
 
     if (shouldDisplayQRCodeInTerminal && isPrimaryNode) {
@@ -317,16 +350,6 @@
       });
     }
 
-    const listenAddress = (() => {
-      if (process.env.COMM_LISTEN_ADDR) {
-        return process.env.COMM_LISTEN_ADDR;
-      } else if (process.env.NODE_ENV === 'development') {
-        return undefined;
-      } else {
-        return 'localhost';
-      }
-    })();
-
     server.listen(parseInt(process.env.PORT, 10) || 3000, listenAddress);
   }
 })();