chore(netlify-cms): update for v2, add standalone build system

[erquhart]

Fixes #4516, #6048, #6248.

• Update to v2 API's
• Use a standalone webpack compiler to ensure against impacts on main site
• Accept custom preview pane styles (even raw preprocessor styles) via plugin options
• Optionally disable identity widget (ported from gatsby-plugin-netlify-cms: allow identity widget disabling #5942)
• Make custom preview templates and styles work during local development
• Added a few other small options (documented)

[gatsbybot]

Deploy preview for gatsbygram ready!

Built with commit 23a4816

https://deploy-preview-6356--gatsbygram.netlify.com

[gatsbybot]

Deploy preview for using-drupal ready!

Built with commit 23a4816

https://deploy-preview-6356--using-drupal.netlify.com

[erquhart]

Not sure why those failures are happening, not seeing them locally.

[m-allanson]

Nice work, that's a much simpler gatsby-node.js! Adding Parcel seems like a fairly heavy dependency though - what are your thoughts on using the same onPostBuild approach to run a separate build, but configured with webpack's Node API instead of using Parcel?

Those test failures seem odd - I can replicate them by checking out this branch and doing the following:

yarn
yarn run bootstrap
yarn run test

I'll do some more digging to see if I can find what's causing the failures.

[erquhart]

That's fair, I'll switch it to webpack.

[emanueleperuffo]

I've created PR #6391

[erquhart]

@emanueleperuffo I mentioned this on your PR, but THANK YOU so much for digging into this. Our efforts just happened to overlap as the Gatsby/Netlify CMS use case has been one of the "fires I've let burn" for a bit while tending to other things.

I took the opportunity to finish the v2 update, and also to fix longstanding issues with using custom preview pane styles during Gatsby local development.

There are a lot of known issues with this plugin, especially as documented in #4516, and I think this PR addresses all known issues while keeping the plugin minimally complex.

@m-allanson all finished here.

[erquhart]

The test and deploy failures are present in other pull requests too, I don't believe any of them are related to this PR.

[ascorbic]

The CI builds are failing because this is an undefined variable.

[erquhart]

Ah, I see that now - it's not actually undefined, but failing linting. Weird that it passes locally.

[erquhart]

@m-allanson @KyleAMathews I don't believe this PR is responsible for any test failures - can this be merged?

[KyleAMathews]

Hmm can't recreate the test errors locally... @m-allanson or @pieh — any idea what those test errors mean?

[m-allanson]

It turns out that React isn't included as a dependency anywhere in the repo. The netlify-cms package depends on React, but that is now a peerDependency. I guess this wasn't showing up locally as the old React packages would still be hanging out in node_modules

@erquhart I got this working by adding react and react-dom as devDepencies of packages/gatsby. I have a commit locally but don't have access to push it to your repo. Feel free to create your own commit for this instead.

[m-allanson]

this PR addresses all known issues while keeping the plugin minimally complex.

Just wanted to add a big 🎉 for this :)

What is the relation between this PR and #6391? Should just this one be merged?

[shaunbent]

Looking forward to seeing this PR merged, this is currently blocking us from upgrading our site to Gatsby V2.

Thanks for the awesome work @erquhart 🎉😎

[KyleAMathews]

Ahhhh! That makes sense @m-allanson! Weird though you can't push to his repo as I can 🤔

Anyways, I'll make the change and push it right now.

[KyleAMathews]

Yeah, tests are passing. Thanks @erquhart for the nice PR!

[KyleAMathews]

Published PR to gatsby-plugin-netlify-cms@2.0.0-beta.6

[erquhart]

@m-allanson @KyleAMathews good catch on the dependency issue, thank you both so much for digging in.

[steverandy]

Previously we had this line

netlifyIdentityWidget.on(`login`, () => {
  document.location.href = `/admin/`
})

Is there any reason why now it's changed to reloading the page?

[ascorbic]

It seems that this is no longer transpiling TypeScript. My preview templates are TypeScript, and previously this was fine because it used the webpack config from the main site, which includes the TypeScript plugin. Now they're failing to compile. Is there a way of exposing the Netlify Webpack config?

[erquhart]

@steverandy I was actually in the middle of troubleshooting why reloads weren't happening on login, that needs to be changed.

@ascorbic the Netlify CMS webpack config uses any plugins that loaded before the Netlify CMS plugin itself. Try moving your Typescript plugin before the Netlify CMS plugin and see if that works. It would be worth considering how to capture all plugins used, regardless of placement, but the current setup should work for most.

[emanueleperuffo]

Is it possible to use version > 2.0.1 like 2.0.1-beta.6 so npm doesn't update the package to 2.0.1 which is for gatsby v1?

[pieh]

@emanueleperuffo Hmmm, we should bump major version for v2 - we did that some time ago for packages in this repository, but it seems like we have missed this package

[ascorbic]

Is anyone able to get this to generate the styles.css for custom preview styles? I opened a separate issue, #6641, as I thought it may have been a documentation issue, but I'm starting to think it may be a problem with the webpack config.