Cors-service-mixin

api.service.js

const ApiGateway = require("moleculer-web");
const CorsMixin = require('./cors.service');

module.exports = {
	name: "api",
	mixins: [CorsMixin,ApiGateway],

	settings: {
		port: process.env.PORT || 3000,
        allowedOrigins: ['http://localhost:8080'],
        allowedMethods: ['OPTIONS', 'GET', 'PUT', 'POST', 'DELETE'],
		routes: [{
			path: "/",
			whitelist: [
				// Access to any actions in all services
				"*"
			],
			aliases:{
				"GET hello/:name": "greeterService.hello"
			}
  }]

	}
};

cors.service.js

const {contains} = require('ramda');
module.exports = {
    name: 'cors-service',
    settings: {
        allowedOrigins: [],
        allowedMethods: [],
        allowedHeaders: [],
        // executing the mixin for root path
        routes: [
            {
                path: '/',
                // use the onBeforeCall to return 200 for options call
                onBeforeCall(ctx, route, req, res) {
                    this.logger.info("starting the CORS check for route " + route.path);
                    if (req.method === 'OPTIONS') {
                        res.writeHead(200);
                        res.end();
                    }
                },
                // process and return the correct headers after the call
                onAfterCall(ctx, route, req, res, data) {
                    this.logger.info("setting CORS custom headers");
                    res.setHeader("Access-Control-Allow-Origin",
                        contains(ctx.meta.origin, this.settings.allowedOrigins) ?
                            ctx.meta.origin :
                            '');
                    res.setHeader('Access-Control-Allow-Methods',
                        this.settings.allowedMethods.length ?
                            this.settings.allowedMethods.join(',') :
                            '');
                    res.setHeader('Access-Control-Allow-Headers',
                        this.settings.allowedHeaders.length ?
                            this.settings.allowedHeaders.join(',') :
                            '*');
                }
            }
        ]
    },

};