preact.config.js

import envVars from 'preact-cli-plugin-env-vars';

module.exports = function(config, env, helpers) {
  if (config.devServer) {
    config.devServer.proxy = [
      {
        // proxy requests matching a pattern:
        path: '/api/**',

        // where to proxy to:
        target: process.env.BACKEND,

        // optionally change Origin: and Host: headers to match target:
        // changeOrigin: true,
        // changeHost: true,

        // optionally mutate request before proxying:
        // pathRewrite: function(path, request) {
        //   // you can modify the outbound proxy request here:
        //   delete request.headers.referer;
        //
        //   // common: remove first path segment: (/api/**)
        //   return '/' + path.replace(/^\/[^\/]+\//, '');
        // },

        // optionally mutate proxy response:
        // onProxyRes: function(proxyRes, req, res) {
        //   // you can modify the response here:
        //   proxyRes.headers.connection = 'keep-alive';
        //   proxyRes.headers['cache-control'] = 'no-cache';
        // }
      }
    ];
  }
  envVars(config, env, helpers);
};