Initial commits

README.adoc

@@ -129,6 +129,17 @@ Below is a guide for setting up the Heroku application from scratch should there
 
 == Environment variables
 
+`PROXY`::
+(Required) Set to `true` if se-edu-bot is served behind a reverse proxy (e.g. ngrok or heroku).
+Given that we host se-edu-bot on heroku and use ngrok for development,
+this should usually be set to `true`.
+
+`PORT`::
+TCP port which the server will listen on.
+There is no need to explicitly set this on Heroku,
+as Heroku will automatically set the `PORT` environment variable.
+(Default: 5000)
+
 == Coding standard
 
 We follow the oss-generic coding standard.

package.json

@@ -22,10 +22,18 @@
   },
   "dependencies": {
     "dotenv": "^4.0.0",
+    "http-errors": "^1.6.1",
+    "koa": "^2.2.0",
+    "koa-compose": "^4.0.0",
+    "koa-route": "^3.2.0",
     "source-map-support": "^0.4.15"
   },
   "devDependencies": {
     "@types/dotenv": "^4.0.0",
+    "@types/http-errors": "^1.5.34",
+    "@types/koa": "^2.0.39",
+    "@types/koa-compose": "^3.2.2",
+    "@types/koa-route": "^3.2.0",
     "@types/node": "^7.0.31",
     "@types/source-map-support": "^0.4.0",
     "nodemon": "^1.11.0",

server.ts

@@ -4,6 +4,58 @@ sourceMapSupport.install();
 import dotenv = require('dotenv');
 dotenv.config();
 
+import Koa = require('koa');
+import koaRoute = require('koa-route');
+
+/**
+ * Server app configuration.
+ */
+export interface AppConfig {
+    /**
+     * True if the server is being served behind a proxy.
+     */
+    proxy: boolean;
+}
+
+/**
+ * Creates a Koa Application with the provided `appConfig`.
+ */
+export function createApp(appConfig: AppConfig): Koa {
+    const app = new Koa();
+    app.proxy = appConfig.proxy;
+
+    app.use(koaRoute.get('/', async ctx => {
+        ctx.body = 'Hello world!';
+    }));
+
+    return app;
+}
+
+/**
+ * Extracts {@link AppConfig} from `process.env`.
+ */
+function extractAppConfigFromEnv(): AppConfig {
+    return {
+        proxy: !!extractEnvVar('PROXY', ''),
+    };
+}
+
+/**
+ * Extracts an environment variable from `process.env`.
+ * @throws {Error} Environment variable not defined and `defaultValue` not provided.
+ */
+function extractEnvVar(key: string, defaultValue?: string): string {
+    if (typeof process.env[key] === 'string' && process.env[key]) {
+        return process.env[key];
+    } else if (typeof defaultValue !== 'undefined') {
+        return defaultValue;
+    } else {
+        throw new Error(`$${key} not defined`);
+    }
+}
+
 if (require.main === module) {
-    console.log('Hello world!');
+    const port = parseInt(extractEnvVar('PORT', '5000'), 10);
+    const app = createApp(extractAppConfigFromEnv());
+    app.listen(port);
 }