BULL-3221: express mvp

• added unit tests, note that the dataLayer unit tests are also overwritten when dataLayer is replaced by a real implementation
• added production dockerfile

src/controller/controller.js

+const { getDbVersion, healthCheck } = require('../data/dataLayer');
+const { jwtDecode } = require('jwt-decode');
+const apiVersion = "0.0.1";
+
+/** 
+ * Perform a health check by ensuring data layer connectivity is healthy.
+ * */ 
+exports.getHealth = async (req, res) => {
+    const dbHealth = await healthCheck();
+
+    if (!dbHealth) {
+        console.log("Unable to get DB health, returning 500 response");
+        res.status(500).json({
+            status: 500,
+            message: "Internal Server Error"
+        });
+        return;
+    }
+
+    let statusCode = 500;
+    if (dbHealth.healthy) {
+        statusCode = 200;
+    }
+    res.status(statusCode).json({
+        status: statusCode,
+        message: dbHealth.message
+    });
+};
+
+/**
+ * Return the user's current JWT. Useful to ensure that the app is integrated properly in the Party Bus infrastructure.
+ */
+exports.getUser = async (req, res) => {
+    try {
+        const header = req.headersDistinct?.Authorization?.[0] || req.headersDistinct?.authorization?.[0];
+        const responseData = header ? jwtDecode(header) : { result: "no authorization header found" };
+        res.status(200).json(responseData);
+    } catch (error) {
+        const errorResponse = {
+            error: 'Unable to read authorization header as jwt! Error: ' + error.message
+        }
+        res.status(400).json(errorResponse);
+    }
+};
+
+/**
+ * Return basic version information. Useful to check that the app can query from its database.
+ */
+exports.getVersion = async (req, res) => {
+    const dbVersion = await getDbVersion();
+    const versionResponse = {
+        apiVersion: apiVersion,
+        dbVersion: dbVersion
+    };
+    res.status(200).json(versionResponse);
+};