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Customize response HTTP headers

Front-Commerce leverages helmet to send security-related HTTP headers. This guide explains how to customize those HTTP headers.

As mentioned in helmet's README file: "It's not a silver bullet, but it can help" preventing security issues. Here is how to change HTTP headers sent by your application.

Content-Security-Policy (aka CSP)

According to Content Security Policy (CSP) MDN article:

Content Security Policy (CSP) is an added layer of security that helps to detect and mitigate certain types of attacks, including Cross-Site Scripting (XSS) and data injection attacks. These attacks are used for everything from data theft to site defacement to distribute malware.

In a nutshell, the Content-Security-Policy header instructs the browser on how it should handle resources such as JavaScript, CSS, images, … or anything it can load on a page.

In Front-Commerce, the content of this header can be controlled by tweaking contentSecurityPolicy configuration into config/website.js. This is where you will be able to let the browser know that for instance it can safely load a JavaScript file from a given origin.

Other headers

To customize other headers send by default, you have to write a custom express middleware.

For instance, here is how you can to set the Referer-Policy header to origin-when-cross-origin:

  1. create module and add a server/module.config.js to declare a global server middleware. This file would look like:

    import setReferrerPolicy from "./express/setReferrerPolicy";

    export default {
    endpoint: {
    __dangerouslyOverrideBasePathChecks: true,
    path: "/",
    router: setReferrerPolicy,
  2. write the middleware that will set the header. In this middleware, you can use any of the function exposed by helmet.

    // imported in the previous snippet
    import { Router } from "express";
    import { referrerPolicy } from "helmet";

    const setReferrerPolicy = () => {
    const router = new Router();

    router.use(referrerPolicy({ policy: "origin-when-cross-origin" }));

    return router;

    export default setReferrerPolicy;

And that's it. When the module having the server/module.config.js and server/express/setReferrerPolicy.js files will be enabled in .front-commerce.js, Front-Commerce will set the Referrer-Policy header to origin-when-cross-origin.