Cannot Resolve 'uws', Update README or "package.json"?

Note: for support questions, please use one of these channels: stackoverflow or slack

You want to:

• report a bug
• request a feature

Current behaviour

I downloaded the example project webpack-build-server from socket.io’s master branch, run npm install to install the dependencies, and finally run npm run build to try to bundle the server, but webpack gives me the following errors:

ERROR in ./~/engine.io/lib/server.js
Module not found: Error: Can't resolve 'uws' in '/Users/ZehuaChen/Downloads/socket.io-master/examples/webpack-build-server/node_modules/engine.io/lib'
 @ ./~/engine.io/lib/server.js 107:27-41
 @ ./~/engine.io/lib/engine.io.js
 @ ./~/socket.io/lib/index.js
 @ ./lib/index.js

Steps to reproduce (if the current behaviour is a bug)

1. Download socket.io’s master branch
2. Go to examples/webpack-build-server;
3. Run npm install;
4. Run npm run build;

Note: the best way to get a quick answer is to provide a failing test case, by forking the following fiddle for example.

Expected behaviour

A server.js file should be produced in dist folder.

Setup

• OS: macOS Hight SIerra
• browser: Safari
• socket.io version: 2.0.3

Other information (e.g. stacktraces, related issues, suggestions how to fix)

These are what’s printed in my terminal

> webpack-build-server@1.0.0 build /Users/ZehuaChen/Downloads/socket.io-master/examples/webpack-build-server
> webpack --config ./support/webpack.config.js

Hash: 997a1fd1ee0b1b064485
Version: webpack 2.7.0
Time: 468ms
    Asset    Size  Chunks                    Chunk Names
server.js  401 kB       0  [emitted]  [big]  main
   [0] ./~/debug/src/index.js 263 bytes {0} [built]
   [7] ./~/socket.io-parser/index.js 8.04 kB {0} [built]
  [16] ./~/engine.io/lib/socket.js 11.6 kB {0} [built]
  [17] ./~/engine.io/lib/transports/index.js 509 bytes {0} [built]
  [19] ./~/socket.io-parser/is-buffer.js 712 bytes {0} [built]
  [20] ./~/socket.io/lib/namespace.js 5.81 kB {0} [built]
  [31] ./~/socket.io/lib/index.js 12.9 kB {0} [built]
  [32] ./lib/index.js 474 bytes {0} [built]
  [43] ./~/engine.io/lib/engine.io.js 2.38 kB {0} [built]
  [44] ./~/engine.io/lib/server.js 15.1 kB {0} [built]
  [58] ./~/socket.io-adapter/index.js 5.44 kB {0} [built]
  [59] ./~/socket.io-client/package.json 3.19 kB {0} [built]
  [61] ./~/socket.io/lib 160 bytes {0} [built]
  [62] ./~/socket.io/lib/client.js 5.9 kB {0} [built]
  [63] ./~/socket.io/lib/parent-namespace.js 917 bytes {0} [built]
    + 59 hidden modules

WARNING in ./~/ws/lib/Validation.js
Module not found: Error: Can't resolve 'utf-8-validate' in '/Users/ZehuaChen/Downloads/socket.io-master/examples/webpack-build-server/node_modules/ws/lib'
 @ ./~/ws/lib/Validation.js 10:22-47
 @ ./~/ws/lib/Receiver.js
 @ ./~/ws/index.js
 @ ./~/engine.io/lib/server.js
 @ ./~/engine.io/lib/engine.io.js
 @ ./~/socket.io/lib/index.js
 @ ./lib/index.js

WARNING in ./~/ws/lib/BufferUtil.js
Module not found: Error: Can't resolve 'bufferutil' in '/Users/ZehuaChen/Downloads/socket.io-master/examples/webpack-build-server/node_modules/ws/lib'
 @ ./~/ws/lib/BufferUtil.js 35:21-42
 @ ./~/ws/lib/Receiver.js
 @ ./~/ws/index.js
 @ ./~/engine.io/lib/server.js
 @ ./~/engine.io/lib/engine.io.js
 @ ./~/socket.io/lib/index.js
 @ ./lib/index.js

WARNING in ./~/socket.io/lib/index.js
113:11-32 Critical dependency: the request of a dependency is an expression

ERROR in ./~/engine.io/lib/server.js
Module not found: Error: Can't resolve 'uws' in '/Users/ZehuaChen/Downloads/socket.io-master/examples/webpack-build-server/node_modules/engine.io/lib'
 @ ./~/engine.io/lib/server.js 107:27-41
 @ ./~/engine.io/lib/engine.io.js
 @ ./~/socket.io/lib/index.js
 @ ./lib/index.js

npm ERR! code ELIFECYCLE
npm ERR! errno 2
npm ERR! webpack-build-server@1.0.0 build: `webpack --config ./support/webpack.config.js`
npm ERR! Exit status 2
npm ERR!
npm ERR! Failed at the webpack-build-server@1.0.0 build script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/ZehuaChen/.npm/_logs/2018-05-17T21_30_47_624Z-debug.log

Update

I install uws package manually and it seems to work. Can someone update the README file or package.json since it’s really hard for a beginner like me to figure this out.

[despagito]

It doesn’t stop you from npm start, just ignore the error.

[millsp]

If you are compiling for node only, you should add the option then the error will disappear. You should add to your configuration file:

{
        ...
        target: 'node'
       ...
}

Otherwise, you are compiling for web only, then no option needs to be passed (default=‘web’) (or target=‘web’) but you should exclude ‘uws’ from being bundled, since it doesn’t work in the browser. In this case you should rather add:

{
        ...
        externals: {
            uws: "uws"
        },
       ...
}