Node-mysql2: Cannot read property 'fromPacket' of undefined

[JeremieDemarchez]

Hello,

I use mysql2 module in nodejs with serverless framework, and I get the following issue :
{
"errorType": "TypeError",
"errorMessage": "Cannot read property 'fromPacket' of undefined",
"stack": [
"TypeError: Cannot read property 'fromPacket' of undefined",
" at a._fatalError [as handshakeInit] (/var/task/webpack:/node_modules/mysql2/lib/commands/client_handshake.js:89:18)",
" at a.this [as execute] (/var/task/webpack:/node_modules/mysql2/lib/commands/command.js:33:9)",
" at T.handlePacket (/var/task/webpack:/node_modules/mysql2/lib/connection.js:403:9)",
" at s._handleNetworkError [as onPacket] (/var/task/webpack:/node_modules/mysql2/lib/connection.js:67:34)",
" at sequenceId [as executeStart] (/var/task/webpack:/node_modules/mysql2/lib/packet_parser.js:70:15)",
" at Socket.this (/var/task/webpack:/node_modules/mysql2/lib/connection.js:74:29)",
" at Socket.emit (events.js:198:13)",
" at addChunk (_stream_readable.js:288:12)",
" at readableAddChunk (_stream_readable.js:269:11)",
" at Socket.Readable.push (_stream_readable.js:224:10)"
]
}

To "solve" this issue, webpack minification must be disable : set "mode" to "developpment" in webpack.config.js.

Is there a way to make it compatible with webpack minification ?

[cain004]

I'm having the same issue. Changing the mode does work, but not ideal.

[sidorares]

linking related: https://github.com/sidorares/node-mysql2/pull/992#issuecomment-538838598

@cain004 what version are you using? v1.7.0 removed some dynamic requires to be more compatible with bundlers

[sidorares]

also @cain004 @JeremieDemarchez if you can prepare simple self-contained way to get same error for me that would be really helpful

[cain004]

@sidorares using v1.7.0. Below is a sample project with some brief notes in the handler:
https://github.com/cain004/mysql2-service

[azuldotdev]

Try using _keep_fnames_ in webpack config:

const TerserPlugin = require('terser-webpack-plugin');

[...]

optimization: {
    minimizer: [
      new TerserPlugin({
        terserOptions: {
          keep_fnames: true
        }
      })
    ]
  },

[thinhbuzz]

Try using _keep_fnames_ in webpack config:

const TerserPlugin = require('terser-webpack-plugin');

[...]

optimization: {
    minimizer: [
      new TerserPlugin({
        terserOptions: {
          keep_fnames: true
        }
      })
    ]
  },

it's working

[sidorares]

@cain004 can you try what @azulinternet suggested? If it works for you I'll close this issue

[cain004]

using webpack-node-externals does the trick.

webpack.config.js

const path = require('path');
const slsw = require('serverless-webpack');
const nodeExternals = require('webpack-node-externals');

module.exports = {
  mode: slsw.lib.webpack.isLocal ? 'development' : 'production',
  entry: slsw.lib.entries,
  devtool: slsw.lib.webpack.isLocal ? 'cheap-module-eval-source-map' : 'source-map',
  resolve: {
    extensions: ['.mjs', '.json', '.ts'],
    symlinks: false,
    cacheWithContext: false,
  },
  output: {
    libraryTarget: 'commonjs',
    path: path.join(__dirname, '.webpack'),
    filename: '[name].js',
  },
  target: 'node',
  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
    //   }
    // })
  ],
};

[dashmug]

Using nodeExternals is a workaround not a fix. It simply tells webpack not to bundle mysql2.

[liftyourgame]

If I use nodeExternals then my Lambda does not include the required dependencies. I've tried setting:

minimize: false
mode: 'development'

Still I get this error. I'm not using serverless but CDK to create my infrastructure.