Add CORS helper

packages/core/micro-server/README.md

@@ -1,3 +1,54 @@
 # @alwatr/micro-server
 
 Elegant powerful nodejs server for microservice use cases, written in tiny TypeScript module.
+
+## Usage
+
+### Create server
+
+```typescript
+import {AlwatrMicroServer} from '@alwatr/micro-server';
+
+import type {AlwatrConnection} from '@alwatr/micro-server';
+
+const app = new AlwatrMicroServer(8000);
+
+app.route('all', '/', async (connection: AlwatrConnection) => {
+  connection.reply({
+    ok: true,
+    statusCode: 200,
+    data: {
+      app: 'Alwatr Microservice',
+      message: 'Hello ;)',
+    },
+  });
+});
+```
+
+### Middleware
+
+#### CORS Helper
+
+Read about [Cross-Origin Resource Sharing](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS).
+
+```typescript
+app.route('all', '/', async (connection) => {
+  connection.reply(
+    {
+      ok: true,
+      statusCode: 200,
+      data: {
+        app: 'Alwatr Microservice',
+        message: 'Hello World',
+      },
+    },
+    {
+      corsHelper: {
+        allowOrigin: 'https://developer.mozilla.org', // That should not end with "/"
+        allowMethod: '*',
+        maxAge: 5 * 60, // 5 Minute
+      },
+    }
+  );
+});
+```

packages/core/micro-server/src/micro-server.ts

@@ -2,7 +2,9 @@ import {createServer} from 'http';
 
 import {alwatrRegisteredList, createLogger} from '@alwatr/logger';
 
-import type {Methods, ReplyContent} from './type.js';
+import {corsHelper} from './middleware/cors-helpers.js';
+
+import type {Methods, ReplyContent, ResponseOptions} from './type.js';
 import type {IncomingMessage, ServerResponse} from 'http';
 
 alwatrRegisteredList.push({
@@ -14,7 +16,7 @@ export class AlwatrMicroServer {
   protected logger = createLogger(`micro-server:${this.port}`);
   protected server = createServer(this.handleRequest);
 
-  constructor(protected port: number, autoListen = true) {
+  constructor(protected port: number, autoListen = true, public options?: ResponseOptions) {
     this.logger.logMethodArgs('new', {port, listen: autoListen});
     this.server = createServer(this.handleRequest.bind(this));
 
@@ -90,7 +92,7 @@ export class AlwatrMicroServer {
       return;
     }
 
-    const connection = new AlwatrConnection(incomingMessage, serverResponse);
+    const connection = new AlwatrConnection(incomingMessage, serverResponse, this.options);
     const route = connection.url.pathname;
     const method = connection.incomingMessage.method?.toLowerCase();
 
@@ -143,7 +145,11 @@ export class AlwatrConnection {
 
   readonly body = this._getRequestBody();
 
-  constructor(public incomingMessage: IncomingMessage, public serverResponse: ServerResponse) {
+  constructor(
+    public incomingMessage: IncomingMessage,
+    public serverResponse: ServerResponse,
+    public options?: ResponseOptions,
+  ) {
     this.logger.logMethodArgs('new', {method: incomingMessage.method, url: incomingMessage.url});
   }
 
@@ -210,6 +216,10 @@ export class AlwatrConnection {
       );
     }
 
+    if (this.options?.corsHelper !== undefined) {
+      corsHelper(this.serverResponse, this.options?.corsHelper);
+    }
+
     this.serverResponse.writeHead(content.statusCode ?? 200, {
       'Content-Length': body.length,
       'Content-Type': 'application/json',

packages/core/micro-server/src/middleware/cors-helpers.ts

@@ -0,0 +1,33 @@
+import {CorsHelperHeader} from '../type';
+
+import type {ServerResponse} from 'http';
+
+/**
+ * Set CORS helper header.
+ * https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS
+ */
+export function corsHelper(response: ServerResponse, header: CorsHelperHeader): void {
+  if (header.allowOrigin !== undefined) {
+    response.setHeader('Access-Control-Allow-Origin', header.allowOrigin);
+  }
+
+  if (header.allowMethods !== undefined) {
+    response.setHeader('Access-Control-Allow-Methods', header.allowMethods);
+  }
+
+  if (header.allowHeaders !== undefined) {
+    response.setHeader('Access-Control-Allow-Headers', header.allowHeaders);
+  }
+
+  if (header.exposeHeaders !== undefined) {
+    response.setHeader('Access-Control-Expose-Headers', header.exposeHeaders);
+  }
+
+  if (header.allowCredentials !== undefined) {
+    response.setHeader('Access-Control-Allow-Credentials', String(header.allowCredentials));
+  }
+
+  if (header.maxAge !== undefined) {
+    response.setHeader('Access-Control-Max-Age', header.maxAge);
+  }
+}

packages/core/micro-server/src/type.ts

@@ -11,6 +11,19 @@ interface ReplySuccessContent {
   data: Record<string, unknown>;
 }
 
+export interface ResponseOptions {
+  corsHelper?: CorsHelperHeader;
+}
+
+export interface CorsHelperHeader {
+  allowOrigin: string;
+  allowMethods?: string;
+  allowHeaders?: string;
+  exposeHeaders?: string;
+  allowCredentials?: boolean;
+  maxAge?: number;
+}
+
 export type ReplyContent = ReplyFailedContent | ReplySuccessContent;
 
 export type Methods = ('all' | 'get' | 'post' | 'put' | 'delete' | 'patch' | 'options') & string;

packages/starter/microservice/src/app.ts

@@ -2,4 +2,10 @@ import {AlwatrMicroServer} from '@alwatr/micro-server';
 
 import {config} from './config.js';
 
-export const app = new AlwatrMicroServer(config.port);
+export const app = new AlwatrMicroServer(config.port, undefined, {
+  corsHelper: {
+    allowOrigin: '*',
+    allowMethods: '*',
+    maxAge: 5 * 60, // 5 min
+  },
+});

packages/starter/microservice/src/route/echo.ts

@@ -1,6 +1,8 @@
 import {app} from '../app.js';
 
-app.route('post', '/echo', async (connection) => {
+import type {AlwatrConnection} from '@alwatr/micro-server';
+
+app.route('post', '/echo', async (connection: AlwatrConnection) => {
   const jsonBody = await connection.requireJsonBody();
   if (jsonBody == null) return;
 

packages/starter/microservice/src/route/home.ts

@@ -1,6 +1,8 @@
 import {app} from '../app.js';
 
-app.route('all', '/', async (connection) => {
+import type {AlwatrConnection} from '@alwatr/micro-server';
+
+app.route('all', '/', async (connection: AlwatrConnection) => {
   connection.reply({
     ok: true,
     data: {