Cannot use hot reloading in Docker (continuation of #6722)

[dirslashls]

Have you read the Contributing Guidelines on issues?

• I have read the Contributing Guidelines on issues.

Prerequisites

• I'm using the latest version of Docusaurus.
• I have tried the npm run clear or yarn clear command.
• I have tried rm -rf node_modules yarn.lock package-lock.json and re-installing packages.
• I have tried creating a repro with https://new.docusaurus.io.
• I have read the console error message carefully (if applicable).

Description

Issue #6722 has been fixed by passing the --poll CLI option as a watch option to WebPack. However, webpack expects the value to be passed either as a number or boolean. As a result, the cli option which ends up passing as a string errors out.

Just simply trying

docusaurus start --poll 1000

gives the following error

[ERROR] ValidationError: Invalid configuration object. Webpack has been initialized using a configuration object that does not match the API schema.
 - configuration.watchOptions.poll should be one of these:
   number | boolean
   -> Enable polling mode for watching.
   Details:
    * configuration.watchOptions.poll should be a number.
      -> `number`: use polling with specified interval.
    * configuration.watchOptions.poll should be a boolean.
      -> `true`: use polling.

Reproducible demo

No response

Steps to reproduce

Locally run the following and see the error

docusaurus start --poll 1000

Expected behavior

Ideally the watching should take effect by polling.

Actual behavior

The server doesn't start and errors out.

See webpack/webpack#3048 which mentions similar issue of passing the option via env variable which is treated as a string.

Your environment

No response

Self-service

• I'd be willing to fix this bug myself.

[slorber]

Thanks, can reproduce 👍

Likely a tiny parsing issue before we apply the validation.

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Good first issue for an external contributor - please send a PR directly with a fix, don't claim the issue