Allow user to set WebpackDevServer watchOptions.poll option for react-scripts start

[spaugh]

This could potentially be done by modifying the instantiation of the WebpackDevServer in start.js to look like:

...
watchOptions: {
  ignored: /node_modules/,
  poll: process.env.REACT_APP_POLL || undefined,
}
...

This use case is important to me (and others) because I'm developing in a Docker container, which has issues with inotify (due to mounting volumes with aufs), which precludes the automatic rebuild without the watchOptions poll setting.

[fson]

We try to avoid config flags like this as much as possible. I wonder if it would be possible to somehow detect that we're in an environment like that and fall back to polling automatically.

[YAmikep]

Same for me, I cannot count on inotify since I am using shared folders, vagrant and Virtualbox but I'd like to use polling as a workaround.

[fson]

Chokidar, which Webpack uses for watching changes has an environment to force the use of polling: CHOKIDAR_USEPOLLING. Does this fix the issue with Docker?

CHOKIDAR_USEPOLLING=true npm start

[YAmikep]

Using the env variable works for me.
There does not seem to be an env variable to set the interval though, correct?

[fson]

It seems that an env variable for polling interval has been requested (paulmillr/chokidar#518) and the author has approved the idea, someone just needs to implement it 😃

[gaearon]

Going to close as there is a path forward (described above) that is out of our control.

[jurosh]

Thanks @fson updating script to use CHOKIDAR_USEPOLLING=true react-scripts start helped. Maybe would be nice to put this to react-create-app docs - or just add there reference to webpack docs... what do you guys think? As for many it might be quite an issue to solve watchmode...

[togakangaroo]

Hey, I might be being docker-stupid, but where is this supposed to code? I assumed that you would replace the command but that seems not to be the case?

[airtonix]

you know, if all these nodejs people writing cli apps used nconf.env().argv() we'd be able to set configuration through environment variables or command line arguments.