Fix deploy for CRA2

[chris48s]

Currently the deploy script is broken.

The reason for this is that with react-scripts 1.x, running npm run build would spit out a single file:

File sizes after gzip:

  71.15 KB  build/static/js/main.68b0f98d.js

Then in deploy.sh we'd pick that file out and upload it to S3 as wdiv.js.

From react-scripts 2.x, running npm run build now spits out multiple files:

File sizes after gzip:

  67.04 KB  build/static/js/2.734c1cc1.chunk.js
  2.67 KB   build/static/js/main.bea25228.chunk.js
  761 B     build/static/js/runtime~main.fdfcfda2.js

but our deploy script was only uploading one of them.

This was pretty much impossible to pick up locally. I only noticed it when I deployed to production and and broke everything (side note: it has clearly been ages since I last deployed this 😳 ) . As a quick fix, I downgraded to react-scripts == 1.1.5 locally, ran a build locally and pushed that up to S3. That gets us a non-broken deploy on widget.wheredoivote.co.uk but the repo as it stands will currently break production if we try to deploy.

Fixing this is high priority.

Next steps:

• Set up a dev S3 bucket and point a subdomain at it in CloudFront so we can deploy test builds without breaking production
• Are there config/flags we can pass to react-scripts in order to get it to build down to a single file?
• If not, manually work out how to deploy the multi-file version (the main thing we want to avoid here is making a breaking change for existing users. i.e: if someone has <script type="text/javascript" src="https://widget.wheredoivote.co.uk/wdiv.js"></script> in their website now, I really want to find a way ensure that stays working 🤞 )
• Update deploy.sh as appropriate

[mrwilson]

This seems to be a problem with CRA2 and there's a bunch of bug reports around it.

There is allegedly a workaround (though I haven't tried it yet):

facebook/create-react-app#5306 (comment)

[mrwilson]

This does seem to work:

1. Create a build-without-chunks.js with the contents of the comment above, make it executable
2. Install rewire (npm --save-dev ...)
3. Replace run in package.json with node ./build-without-chunks.js

Happy to open a PR if this is an acceptable stop-gap.

[chris48s]

I'm not sure its a bug as such. Its an intentional and documented change in behaviour, but its a change in behaviour which is problematic for some use cases (including ours). But yes please - do submit a PR. I've not really put any thought into this beyond working out how to un-break prod and writing this up to come back to it. Reading that thread, if we can use that workaround that allows us to build a single file, that sounds ideal. I'd still like to set up a staging environment to test with though, so may sit open for a bit until I get a chance to do that.