Support for a workbox.config.js override file

[jeffposnick]

As per #5111 (comment), there was discussion around the c-r-a v2 timeframe for allowing developers to override the default workbox-webpack-plugin (i.e. service worker generation) configuration with their own external workbox.config.js file. This functionality did not end up making it into the final release, though.

I'd love to see that happen, as putting together a one-size-fits-all default config can leave some developers confused.

I'm happy to submit a PR for that and update the docs accordingly, but I wanted to see if there was any prior art around external, user-controllable configuration files that did make it into the c-r-a v2 release. I'd rather just use a similar approach for Workbox if that solution for another plugin already exists.

If there is no prior art for configuring other plugins in v2, I'd like to confirm that folks like @gaearon and @Timer are fully on board with the idea of external config files, since it's been a contentious point in the past.

[Timer]

There's no prior art, but I'd love to see a solution that scales. We're on board with this configuration but would like to discuss its ergonomics first.

[mymattcarroll]

Are you set using a new external config file? Would you consider extending package.json. e.g.

{
  "name": "app",
  "version": "0.0.0",
  "react-scripts": {
    "workbox-webpack-plugin": {
      "skipWaiting": true
    }
  }
}

[Timer]

I think we'd rather use a file. e.g.

// react-app.config.js
module.exports = {
  workbox(options) {
    // should options be frozen?
    return options
  }
};

[Jeyloh]

Would this simplify the process to add features like push eventlistener and cross origin images etc?

I'd be thrilled

[mymattcarroll]

@jeffposnick, @Timer I would be happy to contribute on this issue if it is open to contributors.

Would you prefer to have a workbox.config.js file catering for only overrides to the workbox-webpack-plugin or a react-app.config.js with an option for workbox-webpack-plugin configuration?

[frederikhors]

I'm in favor of adding a cra.config.js for these config and others, overriding default ones!

[jeffposnick]

Since there's interest from the community, I'm very happy to let others implement the actual code for this feature, and I could contribute relevant documentation once that's in place.

[bakasmarius]

We need to configure CRA to build service-worker.js and precache-manifest.xxxxx.js inside build/static/js folder, and not directly inside build folder root as it is now.
This would result in almost not having to change our production nginx configuration.
So I guess the ability to have a cra.config.js file to owerride some Workbox options would do the trick.