max listeners problem : typescript project and serverless webpack

Question

I am working on a cloud-based project which is built in typescript. To deploy the service we use

build : serverless webpack --stage=dev
deploy: serverless deploy --stage=dev

I am facing the following issue when functions names defined in serverless.yml are more than 10 or 11. sample function declaration in serverless

 func-abc: handler: src/api/get-user-details events: - http: authorizer: ${file(authorizer.yml)} path: /user/{user-id}/ method: GET parameters: paths: user-id: true cors: true

webpack-config.js

const slsw = require('serverless-webpack');
const nodeExternals = require('webpack-node-externals');
const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');
const CopyWebpackPlugin = require('copy-webpack-plugin');

module.exports = {
    context: __dirname,
    mode: 'production',
    entry: slsw.lib.entries,
    devtool: 'source-map',
    resolve: {
        extensions: ['.mjs', '.json', '.ts'],
        symlinks: false,
        cacheWithContext: false,
    },
    output: {
        libraryTarget: 'commonjs',
        path: path.join(__dirname, '.webpack'),
        filename: '[name].js',
    },
    target: 'node',
    optimization: {
        minimize: true,
    },
    externals: [nodeExternals()],
    module: {
        rules: [
            // all files with a `.ts` or `.tsx` extension will be handled by `ts-loader`
            {
                test: /\.(tsx?)$/,
                loader: 'ts-loader',
                exclude: [
                    [
                        path.resolve(__dirname, 'node_modules'),
                        path.resolve(__dirname, '.serverless'),
                        path.resolve(__dirname, '.webpack'),
                    ],
                ],
                options: {
                    transpileOnly: true,
                    experimentalWatchApi: true,
                },
            },
        ],
    },
    plugins: [
        new ForkTsCheckerWebpackPlugin({
            eslint: true,
            eslintOptions: {
                cache: true
            }
        }),
        new CopyWebpackPlugin([
            {from: 'config/*.json', to: ''},
            {from: 'config/*.pem', to: ''},
        ])
    ],
};

(node:9972) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 exit listeners added to [process]. Use emitter.setMaxListeners() to increase limit
(Use `node --trace-warnings ...` to show where the warning was created)

After this warning, code is not getting deployed to AWS.

How to solve this issue.

Thanks in advance.

Answer 1

It worked for me with below webpack.config.js :

const serverlessWebpack = require('serverless-webpack');
const webpack = require('webpack');
const nodeExternals = require('webpack-node-externals');
const TerserPlugin = require('terser-webpack-plugin');
const ForkTsCheckerWebpackPlugin = require('fork-ts-checker-webpack-plugin');

module.exports = {
  devtool: 'inline-cheap-module-source-map',
  entry: serverlessWebpack.lib.entries,
  mode: 'production',
  module: {
    rules: [{
        test: /\.ts$/,
        exclude: /node_modules/,
        loader: 'ts-loader',
        options: {
          // disable type checker - we will use it in fork plugin
          transpileOnly: true
        }
      }
    ],
  },
  node: false,
  externals: [nodeExternals()],
  optimization: {
    minimize: true,
    minimizer: [new TerserPlugin({
      terserOptions: {
        keep_classnames: true,
        keep_fnames: true,
      }
    }
    )],
  },
  resolve: {
    extensions: ['.mjs', '.ts', '.js']
  },
  plugins: [
    new ForkTsCheckerWebpackPlugin()
  ],
  target: 'node',
};

Recently I was solving the similar problem. see here for the detailed guide ( serverless+webpack )