feat(Docker): Add readiness check /ready

src/app/controllers/utils_controller.ts

@@ -1,9 +1,24 @@
 import { Handler } from "../types/express";
+import { query } from "../models/base";
+import { NotReadyError } from "../lib/errors";
 
-export const ping: Handler = (request, response, next) => {
+export const ping: Handler = (_, response, next) => {
   response.jsonApiResponse = {
     status: 200,
     result: "pong",
   };
   next();
 };
+
+export const ready: Handler = async (_, response, next) => {
+  try {
+    await query("SELECT 1");
+  } catch (error) {
+    return next(new NotReadyError());
+  }
+  response.jsonApiResponse = {
+    status: 200,
+    result: "Ready",
+  };
+  next();
+};

src/app/lib/errors.ts

@@ -160,3 +160,9 @@ export class OutcodeNotFoundError extends PostcodesioHttpError {
     super(404, "Outcode not found");
   }
 }
+
+export class NotReadyError extends PostcodesioHttpError {
+  constructor() {
+    super(500, "Service not ready. Database is not available");
+  }
+}

src/config/routes.ts

@@ -10,6 +10,7 @@ import * as terminatedPostcodes from "../app/controllers/terminated_postcodes_co
 export const routes = (app: Express): void => {
   app.get("/", pages.home);
   app.get("/ping", utils.ping);
+  app.get("/ready", utils.ready);
   app.get("/about", pages.about);
   app.get("/docs", pages.documentation);
   app.get("/explore", pages.explore);

test/integration.ts

@@ -56,6 +56,15 @@ describe("Misc", () => {
 });
 
 describe("Utils", () => {
+  describe("Health", () => {
+    it("should return 200 if DB available", async () => {
+      const { body } = await request(app)
+        .get("/ready")
+        .expect(200)
+        .expect("Content-Type", /json/);
+      assert.equal(body.result, "Ready");
+    });
+  });
   describe("Ping", () => {
     it("should pong", async () => {
       const { body } = await request(app)