config-overrides.js

module.exports = {
    // The Webpack config to use when compiling your react app for development or production.
    webpack: function(config, env) {
      // ...add your webpack config
      return config;
    },
    // The Jest config to use when running your jest tests - note that the normal rewires do not
    // work here.
    jest: function(config) {
      // ...add your jest config customisation...
      // Example: enable/disable some tests based on environment variables in the .env file.
      if (!config.testPathIgnorePatterns) {
        config.testPathIgnorePatterns = [];
      }
      if (!process.env.RUN_COMPONENT_TESTS) {
        config.testPathIgnorePatterns.push('<rootDir>/src/components/**/*.test.js');
      }
      if (!process.env.RUN_REDUCER_TESTS) {
        config.testPathIgnorePatterns.push('<rootDir>/src/reducers/**/*.test.js');
      }
      return config;
    },
    // The function to use to create a webpack dev server configuration when running the development
    // server with 'npm run start' or 'yarn start'.
    // Example: set the dev server to use a specific certificate in https.
    devServer: function(configFunction) {
      // Return the replacement function for create-react-app to use to generate the Webpack
      // Development Server config. "configFunction" is the function that would normally have
      // been used to generate the Webpack Development server config - you can use it to create
      // a starting configuration to then modify instead of having to create a config from scratch.
      return function(proxy, allowedHost) {
        // Create the default config by calling configFunction with the proxy/allowedHost parameters
        const config = configFunction(proxy, allowedHost);
  
        // Change the https certificate options to match your certificate, using the .env file to
        // set the file paths & passphrase.
        const fs = require('fs');
        config.https = {
          key: fs.readFileSync(process.env.REACT_HTTPS_KEY, 'utf8'),
          cert: fs.readFileSync(process.env.REACT_HTTPS_CERT, 'utf8'),
          ca: fs.readFileSync(process.env.REACT_HTTPS_CA, 'utf8'),
          passphrase: process.env.REACT_HTTPS_PASS
        };
  
        // Return your customised Webpack Development Server config.
        return config;
      };
    },
    // The paths config to use when compiling your react app for development or production.
    paths: function(paths, env) {
      // ...add your paths config
      return paths;
    },
  }