next.config.js

const withLess = require('@zeit/next-less')

/* Without CSS Modules, with PostCSS */
// module.exports = withLess()

/* With CSS Modules */
// module.exports = withLess({ cssModules: true })
/* With additional configuration on top of CSS Modules */
module.exports = withLess({
  cssModules: true,
  cssLoaderOptions: {
    importLoaders: 1,
    localIdentName: process.env.NODE_ENV === 'production'? "[hash:base64:5]" : "[name]__[local]___[hash:base64:5]",
  },
  webpack: function (config) {
    config.resolve.alias = {
      ...config.resolve.alias,
      '@': `${__dirname}`,
    }
    config.module.rules = [
      ...config.module.rules,
      {
        test: /\.(jpe?g|png|gif|svg)$/i,
        use: [
            {
              loader: 'file-loader',
              options: {
                name(file) {
                  if (process.env.NODE_ENV === 'production') {
                    return '[contenthash].[ext]';
                  }
                  return '[path][name].[ext]';
                },
                publicPath: "/_next/static/images",
                outputPath: "static/images/",
              },
            }
        ]
      }
    ]
    return config;
  }
});