Our theme system injects a magical `settings` object at the top of themes JS modules to allow theme authors to access the settings as configured by admins in the UI. Within this `settings` object, there are a couple of special objects `theme_uploads` and `theme_uploads_local` that contain URLs for all the assets/uploads that the theme has.
For test modules/files, the theme system also injects a `settings` object at the top of tests modules, but it's not the same object as the object that's injected in non-test files. The difference is that in tests we want the settings to have their default values as opposed to any custom values that may exist in the site's database. This ensures that test results are consistent no matter the site that runs them.
However, the `settings` object in tests files currently doesn't have the special objects `theme_uploads` and `theme_uploads_local` which means that if a theme includes an asset that's lazy-loaded, it's not possible to write tests for anything that depends on the lazy-loaded asset because the theme will not be able to load the asset during the tests since `theme_uploads_local` and `theme_uploads` don't exist. This PR adds these special objects inside the `settings` object for test files.
Internal topic: t/71825/52.
Theme javascript is now minified using Terser, just like our core/plugin JS bundles. This reduces the amount of data sent over the network.
This commit also introduces sourcemaps for theme JS. Browser developer tools will now be able show each source file separately when browsing, and also in backtraces.
For theme test JS, the sourcemap is inlined for simplicity. Network load is not a concern for tests.
Previously, compiling theme 'extra_js' was done with a number of steps. Each theme_field would be compiled into its own value_baked column, and then the JavascriptCache content would be built by concatenating all of those compiled values.
This commit streamlines things by removing the value_baked step. The raw value of all extra_js theme_fields are passed directly to the ThemeJavascriptCompiler, and then the result is stored in the JavascriptCache.
In itself, this commit should not cause any behavior change. It is designed to open the door to more advanced compilation features which have interdependencies between different source files (e.g. template colocation, sourcemaps).
Previously we were relying on a highly-customized version of the unmaintained Barber gem for theme template compilation. This commit switches us to use our own DiscourseJsProcessor, which makes use of more modern patterns and will be easier to maintain going forward.
In summary:
- Refactors DiscourseJsProcessor to move multiline JS heredocs into a companion `discourse-js-processor.js` file
- Use MiniRacer's `.call` method to avoid manually escaping JS strings
- Move Theme template AST transformers into DiscourseJsProcessor, and formalise interface for extending RawHandlebars AST transformations
- Update Ember template compilation to use a babel-based approach, just like Ember CLI. This gives each template its own ES6 module rather than directly assigning `Ember.TEMPLATES` values
- Improve testing of template compilation (and move some tests from `theme_javascript_compiler_spec.rb` to `discourse_js_processor_spec.rb`
The source-of-truth for our ember version is now the installed node_module. The `ember_source` gem carries an old version of Ember and so the constant is no longer useful. We'll be dropping the gem soon.
This commit makes a number of improvements to the DiscourseJsProcessor:
1. Remove dependence on the out-of-date Ember template compiler from the ember-rails gem; switch to modern template compiler
2. Refactor to make use of a proper module system with `define`/`require`
3. Introduce `babel-plugin-ember-template-compilation` to enable inline hbs compilation
The `mini-loader` is upgraded to support relative lookup and `require.has`, so that these new JS packages work correctly.
Our theme system is very complex and it can take a while to figure out how to invalidate the various types of caches that are used throughout the theme system. So, having a single helper method that invalidates everything can be useful in emergency situations where there is no time to read through the code and figure out how to clear the various caches.
Internal ticket: t64732.
All `DistributedCache` instances in Discourse are automatically keyed on the `Discourse.git_version`. Normally the theme compiler version is updated via a commit, and everything is fine. However, in some situations, it's possible for the BASE_COMPILER_VERSION to change without a change to the git_version (e.g. when applying patches directly to the codebase).
This commit adds the `BASE_COMPILER_VERSION` to the DistributedCache key to ensure that content from different compiler versions does not leak into other processes.
This is pre-request work to introduce a splash screen while site assets load.
The only change this commit introduces is that it ensures we add the defer attribute to core/plugin/theme .JS files. This will allow us to insert markup before the browser starts evaluating those scripts later on. It has no visual or functional impact on core.
This will not have any impact on how themes and plugins work. The only exception is themes loading external scripts in the </head> theme field directly via script tags. Everything will work the same but those would need to add the defer attribute if they want to keep the benefits introduced in this PR.
Due to default CSP web workers instantiated from CDN based assets are still
treated as "same-origin" meaning that we had no way of safely instansiating
a web worker from a theme.
This limits the theme system and adds the arbitrary restriction that WASM
based components can not be safely used.
To resolve this limitation all js assets in about.json are also cached on
local domain.
{
"name": "Header Icons",
"assets" : {
"worker" : "assets/worker.js"
}
}
This can then be referenced in JS via:
settings.theme_uploads_local.worker
local_js_assets are unconditionally served from the site directly and
bypass the entire CDN, using the pre-existing JavascriptCache
Previous to this change this code was completely dormant on sites which
used s3 based uploads, this reuses the very well tested and cached asset
system on s3 based sites.
Note, when creating local_js_assets it is highly recommended to keep the
assets lean and keep all the heavy working in CDN based assets. For example
wasm files can still live on the CDN but the lean worker that loads it can
live on local.
This change unlocks wasm in theme components, so wasm is now also allowed
in `theme_authorized_extensions`
* more usages of upload.content
* add a specific test for upload.content
* Adjust logic to ensure that after upgrades we still get a cached local js
on save
aa1442fdc3 split theme stylesheets so that every component gets its own stylesheet. Therefore, there is now no need for parent themes to collate the settings/variables of its children during scss compilation.
Technically this is a breaking change for any themes which depend on the settings/variables of their child components. That was never a supported/recommended arrangement, so we don't expect this to cause issues.
If a theme is updated to introduce a new setting AND immediately make use of it in a stylesheet, then an error was being shown. This is because the stylesheet compilation was using the theme's cached settings, and the cache is only cleared **after** the theme has finished compiling.
This commit updates the SCSS compilation to use uncached values for settings. A similar fix was applied to other parts of theme compilation back in 2020: (a51b8d9c66)
The previous Discourse.cache usage was different to how other theme-related caching is handled, and also requires reaching out to redis every time. The common theme cache is held in memory (as a DistributedCache)
There is a couple of layers of caching for theme JavaScript in Discourse:
The first layer is the `javascript_caches` table in the database. When a theme
with JavaScript files is installed, Discourse stores each one of the JavaScript
files in the `theme_fields` table, and then concatenates the files, compiles
them, computes a SHA1 digest of the compiled JavaScript and store the results
along with the SHA1 digest in the `javascript_caches` table.
Now when a request comes in, we need to render `<script>` tags for the
activated theme(s) of the site. To do this, we retrieve the `javascript_caches`
records of the activated themes and generate a `<script>` tag for each record.
The `src` attribute of these tags is a path to the `/theme-javascripts/:digest`
route which simply responds with the compiled JavaScript that has the requested
digest.
The second layer is a distributed cache whose purpose is to make rendering
`<script>` a lot more efficient. Without this cache, we'd have to query the
`javascript_caches` table to retrieve the SHA1 digests for every single
request. So we use this cache to store the `<script>` tags themselves so that
we only have to retrieve the `javascript_caches` records of the activated
themes for the first request and future requests simply get the cached
`<script>` tags.
What this commit does it ensures that the SHA1 digest in the
`javascript_caches` table stay the same across compilations by adding an order
by id clause to the query that loads the `theme_fields` records. Currently, we
specify no order when retrieving the `theme_fields` records so the order in
which they're retrieved can change across compilations and therefore cause the
SHA1 to change even though the individual records have not changed at all.
An inconsistent SHA1 digest across compilations can cause the database cache
and the distributed cache to have different digests and that causes the
JavaScript to fail to load (and if the theme heavily customizes the site, it
gives the impression that the site is broken) until the cache is cleared.
This can happen in busy sites when 2 concurrent requests recompile the
JavaScript files of a theme at the same time (this can happen when deploying a
new Discourse version) and request A updates the database cache after request B
did, and request B updates the distributed cache after request A did.
Internal ticket: t60783.
Co-authored-by: David Taylor <david@taylorhq.com>
- Update UI to improve contrast
- Make it clear that the message is only shown to administrators
- Add theme name and id to the console output
- Parse the error backtrace to identify the theme-id for post-decoration errors
- Improve console output to include the theme name / URL
- Add `?safe_mode=no_custom` to the admin panel link, so that it will work even if the theme is causing the site to break
In 8e5b945b0f, we reverted the commit but
at the same time resulted in Theme::BASE_COMPILER_VERSION going
backwards which caused problems with themes caching.
This commit bumps the version to clear all the caches.
Follow-up to 8e5b945b0f
- Update UI to improve contrast
- Make it clear that the message is only shown to administrators
- Add theme name and id to the console output
- Parse the error backtrace to identify the theme-id for post-decoration errors
- Improve console output to include the theme name / URL
- Add `?safe_mode=no_custom` to the admin panel link, so that it will work even if the theme is causing the site to break
Similar to site settings, adds support for `refresh` option to theme settings.
```yaml
super_feature_enabled:
type: bool
default: false
refresh: true
```
* FIX: allowed_theme_ids should not be persisted in GlobalSettings
It was observed that the memoized value of `GlobalSetting.allowed_theme_ids` would be persisted across requests, which could lead to unpredictable/undesired behaviours in a multisite environment.
This change moves that logic out of GlobalSettings so that the returned theme IDs are correct for the current site.
Uses get_set_cache, which ultimately uses DistributedCache, which will take care of multisite issues for us.
Before this change, calling `StyleSheet::Manager.stylesheet_details`
for the first time resulted in multiple queries to the database. This is
because the code was modelled in a way where each `Theme` was loaded
from the database one at a time.
This PR restructures the code such that it allows us to load all the
theme records in a single query. It also allows us to eager load the
required associations upfront. In order to achieve this, I removed the
support of loading multiple themes per request. It was initially added
to support user selectable theme components but the feature was never
completed and abandoned because it wasn't a feature that we thought was
worth building.
Setting a key/value pair in DistributedCache involves waiting on the
write to Redis to finish. In most cases, we don't need to wait on the
setting of the cache to finish. We just need to take our return value
and move on.
