(extracted from #23678)
* Move Wizard back into main app, remove Wizard addon
* Remove Wizard-related resolver or build hacks
* Install and enable `@embroider/router`
* Add "wizard" to `splitAtRoutes`
In a fully optimized Embroider app, route-based code splitting more
or less Just Work™ – install `@embroider/router`, subclass from it,
configure which routes you want to split and that's about it.
However, our app is not "fully optimized", by which I mean we are
not able to turn on all the `static*` flags.
In Embroider, "static" means "statically analyzable". Specifically
it means that all inter-dependencies between modules (files) are
explicitly expressed as `import`s, as opposed to `{{i18n ...}}`
magically means "look for the default export in app/helpers/i18n.js"
or something even more dynamic with the resolver.
Without turning on those flags, Embroider behaves conservatively,
slurps up all `app` files eagerly into the primary bundle/chunks.
So, while you _could_ turn on route-based code splitting, there
won't be much to split.
The commits leading up to this involves a bunch of refactors and
cleanups that 1) works perfectly fine in the classic build, 2) are
good and useful in their own right, but also 3) re-arranged things
such that most dependencies are now explicit.
With those in place, I was able to move all the wizard code into
the "app/static" folder. Embroider does not eagerly pull things from
this folder into any bundle, unless something explicitly "asks" for
them via `imports`. Conversely, things from this folder are not
registered with the resolver and are not added to the `loader.js`
registry.
In conjunction with route-based code splitting, we now have the
ability to split out islands of on-demand functionalities from the
main app bundle.
When you split a route in Embroider, it automatically creates a
bundle/entrypoint with the relevant routes/templates/controllers
matching that route prefix. Anything they import will be added to
the bundle as well, assuming they are not already in the main app
bundle, which is where the "app/static" folder comes into play.
The "app/static" folder name is not special. It is configured in
ember-cli-build.js. Alternatively, we could have left everything
in their normal locations, and add more fine-grained paths to the
`staticAppPaths` array. I just thought it would be easy to manage
and scale, and less error-prone to do it this way.
Note that putting things in `app/static` does not guarantee that
it would not be part of the main app bundle. For example, if we
were to add an `import ... from "app/static/wizard/...";` in a
main bundle file (say, `app.js`), then that chunk of the module
graph would be pulled in. (Consider using `await import(...)`?)
Overtime, we can build better tooling (e.g. lint rules and babel
macros to make things less repetitive) as we expand the use of
this pattern, but this is a start.
Co-authored-by: Godfrey Chan <godfreykfc@gmail.com>
This commit introduces the scaffolding for us to easily switch between Ember 3.28 and Ember 5 on the `main` branch of Discourse. Unfortunately, there is no built-in system to apply this kind of flagging within yarn / ember-cli. There are projects like `ember-try` which are designed for running against multiple version of a dependency, but they do not allow us to 'lock' dependency/sub-dependency versions, and are therefore unsuitable for our use in production.
Instead, we will be maintaining two root `package.json` files, and two `yarn.lock` files. For ember-3, they remain as-is. For ember5, we use a yarn 'resolution' to override the version for ember-source across the entire yarn workspace.
To allow for easy switching with minimal diff against the repository, `package.json` and `yarn.lock` are symlinks which point to `package-ember3.json` and `yarn-ember3.lock` by default. To switch to Ember 5, we can run `script/switch ember version 5` to update the symlinks to point to `package-ember5.json` and `package-ember3.json` respectively. In production, and when using `bin/ember-cli` for development, the ember version can also be upgraded using the `EMBER_VERSION=5` environment variable.
When making changes to dependencies, these should be made against the default `ember3` versions, and then `script/regen_ember_5_lockfile` should be used to regenerate `yarn-ember5.lock` accordingly. A new 'Ember Version Lockfiles' GitHub workflow will automate this process on Dependabot PRs.
When running a local environment against Ember 5, the two symlink changes will show up as git diffs. To avoid us accidentally committing/pushing that change, another GitHub workflow is introduced which checks the default Ember version and raises an error if it is greater than v3.
Supporting two ember versions simultaneously obviously carries significant overhead, so our aim will be to get themes/plugins updated as quickly as possible, and then drop this flag.
