Implicit dependency on `webpack-cli`

[daaain]

• Operating System: Mac OS 10.13.4
• Node Version: v8.11.1
• NPM Version: 6.1.0
• webpack Version: 4.12.0
• webpack-dev-server Version: 3.1.4

• This is a bug
• This is a modification request

Code

N/A

Expected Behavior

That webpack-dev-server works with webpack-command.

Or if it specifically needs webpack-cli it's made an explicit dependency.

Actual Behavior

webpack-dev-server crashes as it's trying to directly access webpack-cli/bin/config-yargs.

> webpack-dev-server --mode development --hot

The CLI moved into a separate package: webpack-cli.
Please install 'webpack-cli' in addition to webpack itself to use the CLI.
-> When using npm: npm install webpack-cli -D
-> When using yarn: yarn add webpack-cli -D
module.js:549
    throw err;
    ^

Error: Cannot find module 'webpack-cli/bin/config-yargs'
    at Function.Module._resolveFilename (module.js:547:15)
    at Function.Module._load (module.js:474:25)
    at Module.require (module.js:596:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (/xxx/node_modules/webpack-dev-server/bin/webpack-dev-server.js:65:1)
    at Module._compile (module.js:652:30)
    at Object.Module._extensions..js (module.js:663:10)
    at Module.load (module.js:565:32)
    at tryModuleLoad (module.js:505:12)
    at Function.Module._load (module.js:497:3)

For Bugs; How can we reproduce the behavior?

Create a project with webpack-command and without webpack-cli

For Features; What is the motivation and/or use-case for the feature?

[greggb]

I was just about to open this same ticket.

Going forward should we expect webpack-dev-server to only pair with webpack-cli and webpack-command to pair with webpack-serve?

My use case in this situation is not having the time to update my configs for webpack-serve at the moment, so I wanted to retain dev-server while having already moved to webpack-command. Might not be a common enough use case though.

[shellscape]

webpack-serve has no dependency on webpack-command. The choice to have webpack-dev-server depend on the CLI for webpack was a poor design decision made many moons ago, but the ecosystem was much more tightly coupled back then, so it wasn't obvious. This does present a problem for people using webpack-dev-server, especially considering the effort to deprecate webpack-cli currently underway.

[leonid-shevtsov]

Additionally, webpack-dev-server won't start in a Yarn Plug'n'Play-enabled project because p'n'p does not allow implicit dependencies:

Error: Package "webpack-dev-server@3.1.14" (via ".../node_modules/webpack-dev-server/bin/webpack-dev-server.js") is trying to require the package "webpack-cli" (via "webpack-cli/bin/config-yargs") without it being listed in its dependencies (webpack, ansi-html, bonjour, chokidar, compression, connect-history-api-fallback, debug, del, express, html-entities, http-proxy-middleware, import-local, internal-ip, ip, killable, loglevel, opn, portfinder, schema-utils, selfsigned, semver, serve-index, sockjs, sockjs-client, spdy, strip-ansi, supports-color, url, webpack-dev-middleware, webpack-log, yargs, webpack-dev-server)

[alexander-akait]

Close in favor #616 (comment). We solve this for v4