We previously used the window load event as a target to remove the splash. The issue with that is that it means we wait for images to download before we remove the splash.
Ember has a better method that we can use ready(). This PR triggers a custom discourse-ready when that happens and uses that as the baseline for removing the splash.
This PR also adds three new performance marks. discourse-ready, discourse-splash-visible, and discourse-splash-removed
These will help us keep track of performance.
Internal topic /t/65378/81
We previously relied on CSS animation-delay for the splash. This means that we can get inconsistent results based on device/network conditions.
This PR moves us to a more consistent timing based on {request time + 2 seconds}
Internal topic: /t/65378/65
We currently remove the splash screen once Discourse starts booting.
This can be an issue on very slow devices, which can take up to 6 seconds. This PR ensures that we don't remove the splash until the browser has finished parsing all of the site's assets. It won't impact fast devices.
Internal topic /t/65378/60
We use javascript to remove the splash screen when the site boots up. If the user has js disabled, they get stuck on the splash screen.
If the user has js disabled. We don't show the splash screen at all.
We use javascript to remove the splash screen when the site boots up. If the user has js disabled, they get stuck on the splash screen.
If the user has js disabled. We don't show the splash screen at all.
This commit does six things
* changes the animation for the splash screen. To a more subtle animation.
* defers displaying the splash by 1.5 seconds
* defers displaying the splash "loading" text by 2.5 seconds
* defers removing the splash until all Discourse initializers have run
* fixes a display issue in Firefox
* Inlines the SVG as a base64 and inlines the required CSS.
The encoded SVG is hard coded for now, but we will use a helper to generate that based on the file after some testing.
This PR introduces a new hidden site setting that allows admins to display a splash screen while site assets load.
The splash screen can be enabled via the `splash_screen` hidden site setting.
This is what the splash screen currently looks like
5ceb72f085.mp4
Once site assets load, the splash screen is automatically removed.
To control the loading text that shows in the splash screen, you can change the preloader_text translation string in admin > customize > text
On the password_reset error screen, it was totally unused
On the show_confirm_new_email screen, we can load the `vendor` bundle instead. Eventually we should move all this logic into the Ember app
Similar to #17145
This commit moves the SVG sprite container to the <discourse-assets> element.
There is 0 visual or functional changes in this PR. It just tidies up the element view in devTools.
This PR introduces 0 visual or functional changes. The only thing that it changes is that it moves the data-preloaded div (which has the app boot json into the <discourse-assets> element.
See #17078 for a bit more context.
The reason behind this change is that it makes devTools element view a little bit less cluttered.
This is related to #17063 and is also a pre-request for the splash screen work.
This PR introduces 0 visual or functional changes. It just relocates the stylesheets in the load order.
`.css` stylesheets block the browser render. We need to move those out of the <head> tag.
However, they still need to be loaded before core/plugin/theme rendered HTML to avoid FOUC.
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.
This commit migrates all bookmarks to be polymorphic (using the
bookmarkable_id and bookmarkable_type) columns. It also deletes
all the old code guarded behind the use_polymorphic_bookmarks setting
and changes that setting to true for all sites and by default for
the sake of plugins.
No data is deleted in the migrations, the old post_id and for_topic
columns for bookmarks will be dropped later on.
The title had to be added both on the 404 page generated by the server
side, displayed when the user reaches a bad page directly and the 404
page rendered by Ember when a user reaches a missing topic while
navigating the forum.
We have a .ics endpoint for user bookmarks, this
commit makes it so polymorphic bookmarks work on
that endpoint, using the serializer associated with
the RegisteredBookmarkable.
- Make proxy pass `x-forward...` headers, so that Rails can set the host/port correctly in the csp
- Make `testem.js` available on a route which is within the app's default CSP
Previously, accessing the Rails app directly in development mode would give you assets from our 'legacy' Ember asset pipeline. The only way to run with Ember CLI assets was to run ember-cli as a proxy. This was quite limiting when working on things which are bypassed when using the ember-cli proxy (e.g. changes to `application.html.erb`). Also, since `ember-auto-import` introduced chunking, visiting `/theme-qunit` under Ember CLI was failing to include all necessary chunks.
This commit teaches Sprockets about our Ember CLI assets so that they can be used in development mode, and are automatically collected up under `/public/assets` during `assets:precompile`. As a bonus, this allows us to remove all the custom manifest modification from `assets:precompile`.
The key changes are:
- Introduce a shared `EmberCli.enabled?` helper
- When ember-cli is enabled, add ember-cli `/dist/assets` as the top-priority Rails asset directory
- Have ember-cli output a `chunks.json` manifest, and teach `preload_script` to read it and append the correct chunks to their associated `afterFile`
- Remove most custom ember-cli logic from the `assets:precompile` step. Instead, rely on Rails to take care of pulling the 'precompiled' assets into the `public/assets` directory. Move the 'renaming' logic to runtime, so it can be used in development mode as well.
- Remove fingerprinting from `ember-cli-build`, and allow Rails to take care of things
Long-term, we may want to replace Sprockets with the lighter-weight Propshaft. The changes made in this commit have been made with that long-term goal in mind.
tldr: when you visit the rails app directly, you'll now be served the current ember-cli assets. To keep these up-to-date make sure either `ember serve`, or `ember build --watch` is running. If you really want to load the old non-ember-cli assets, then you should start the server with `EMBER_CLI_PROD_ASSETS=0`. (the legacy asset pipeline will be removed very soon)
* FEATURE: Let sites add a sitemap.xml file.
This PR adds the same features discourse-sitemap provides to core. Sitemaps are only added to the robots.txt file if the `enable_sitemap` setting is enabled and `login_required` disabled.
After merging discourse/discourse-sitemap#34, this change will take priority over the sitemap plugin because it will disable itself. We're also using the same sitemaps table, so our migration won't try to create it
again using `if_not_exists: true`.
These were originally very similar, but have diverged over time. This makes it very difficult to manage styling.
This commit moves the noscript header and footer into partials so they can be reused in both the crawler view and the `<noscript>` view. It also makes browser-update render the noscript content **instead of** the `<section id='main'>`, rather than adding adding the noscript inside the `<section>`. This provides better parity with the server-rendered crawler view.
- Ensure the set of rendered `<link rel=stylesheet>` tags is consistent
- Add var() references for all crawler-view styles. Basic color definitions are defined first, as a fallback for super old browsers
* FEATURE: use canonical links in posts.rss feed
Previously we used non canonical links in posts.rss
These links get crawled frequently by crawlers when discovering new
content forcing crawlers to hop to non canonical pages just to end up
visiting canonical pages
This uses up expensive crawl time and adds load on Discourse sites
Old links were of the form:
`https://DOMAIN/t/SLUG/43/21`
New links are of the form
`https://DOMAIN/t/SLUG/43?page=2#post_21`
This also adds a post_id identified element to crawler view that was
missing.
Note, to avoid very expensive N+1 queries required to figure out the
page a post is on during rss generation, we cache that information.
There is a smart "cache breaker" which ensures worst case scenario is
a "page drift" - meaning we would publicize a post is on page 11 when
it is actually on page 10 due to post deletions. Cache holds for up to
12 hours.
Change only impacts public post RSS feeds (`/posts.rss`)
This makes a small improvement to 'cold cache' ember-cli build times, and a large improvement to 'warm cache' build times
The ember-auto-import update means that vendor is now split into multiple files for efficiency. These are named `chunk.*`, and should be included immediately after the `vendor.js` file. This commit also updates the rails app to render script tags for these chunks.
This change was previously merged, and caused memory-related errors on RAM-constrained machines. This was because Webpack 5 switches from multiple worker processes to a single multi-threaded process. This meant that it was hitting node's default heap size limit (~500mb on a 1GB RAM server). Discourse's standard install procedure recommends adding 2GB swap to 1GB-RAM machines, so we can afford to override's Node's default via the `--max-old-space-size` flag.
This reverts commit f4c6a61855 and a8325c9016
This update of ember-auto-import and webpack causes significantly higher memory use during rebuilds. This made ember-cli totally unusable on 1GB RAM / 2GB swap environments. We don't have a specific need for this upgrade right now, so reverting for now.
This makes a small improvement to 'cold cache' ember-cli build times, and a large improvement to 'warm cache' build times
The ember-auto-import update means that vendor is now split into multiple files for efficiency. These are named `chunk.*`, and should be included immediately after the `vendor.js` file. This commit also updates the rails app to render script tags for these chunks
This reverts commit 2c7906999a.
The changes break some things in local development (putting JS files
into minified files, not allowing debugger, and others)
This reverts commit ea84a82f77.
This is causing problems with `/theme-qunit` on legacy, non-ember-cli production sites. Reverting while we work on a fix
This is quite complex as it means that in production we have to build
Ember CLI test files and allow them to be used by our Rails application.
There is a fair bit of glue we can remove in the future once we move to
Ember CLI completely.
A plugin API that allows customizing existing topic-backed static pages, like:
faq, tos, privacy (see: StaticController) The block passed to this
method has to return a SiteSetting name that contains a topic id.
```
add_topic_static_page("faq") do |controller|
current_user&.locale == "pl" ? "polish_faq_topic_id" : "faq_topic_id"
end
```
You can also add new pages in a plugin, but remember to add a route,
for example:
```
get "contact" => "static#show", id: "contact"
```
Under some conditions, these varied responses could lead to cache poisoning, hence the 'security' label.
Previously the Rails application would serve JSON data in place of HTML whenever Ember CLI requested an `application.html.erb`-rendered page. This commit removes that logic, and instead parses the HTML out of the standard response. This means that Rails doesn't need to customize its response for Ember CLI.
We have a couple of site setting, `slow_down_crawler_user_agents` and `slow_down_crawler_rate`, that are meant to allow site owners to signal to specific crawlers that they're crawling the site too aggressively and that they should slow down.
When a crawler is added to the `slow_down_crawler_user_agents` setting, Discourse currently adds a `Crawl-delay` directive for that crawler in `/robots.txt`. Unfortunately, many crawlers don't support the `Crawl-delay` directive in `/robots.txt` which leaves the site owners no options if a crawler is crawling the site too aggressively.
This PR replaces the `Crawl-delay` directive with proper rate limiting for crawlers added to the `slow_down_crawler_user_agents` list. On every request made by a non-logged in user, Discourse will check the User Agent string and if it contains one of the values of the `slow_down_crawler_user_agents` list, Discourse will only allow 1 request every N seconds for that User Agent (N is the value of the `slow_down_crawler_rate` setting) and the rest of requests made within the same interval will get a 429 response.
The `slow_down_crawler_user_agents` setting becomes quite dangerous with this PR since it could rate limit lots if not all of anonymous traffic if the setting is not used appropriately. So to protect against this scenario, we've added a couple of new validations to the setting when it's changed:
1) each value added to setting must 3 characters or longer
2) each value cannot be a substring of tokens found in popular browser User Agent. The current list of prohibited values is: apple, windows, linux, ubuntu, gecko, firefox, chrome, safari, applewebkit, webkit, mozilla, macintosh, khtml, intel, osx, os x, iphone, ipad and mac.
This commit adds token_hash and scopes columns to email_tokens table.
token_hash is a replacement for the token column to avoid storing email
tokens in plaintext as it can pose a security risk. The new scope column
ensures that email tokens cannot be used to perform a different action
than the one intended.
To sum up, this commit:
* Adds token_hash and scope to email_tokens
* Reuses code that schedules critical_user_email
* Refactors EmailToken.confirm and EmailToken.atomic_confirm methods
* Periodically cleans old, unconfirmed or expired email tokens
We have two JS assets which are included in the `<body>` of responses. We were including the `<link rel='preload'` hint alongside the script tag in the body. Instead, we can move the preload hint to the `<head>` so that the browser discovers it earlier, and can start preloading the assets while the body is loading.
Trying to use a local test hostname other than localhost
(e.g. discourse.test )for discourse development was difficult due
the fact that localhost was hardcoded in a few places. This patch
uses existing environment variables to allow a developer to use a
different domain when developing.
Signed-off-by: Ryan Lerch <rlerch@redhat.com>
* FIX: do not display add to calendar for past dates
There is no value in saving past dates into calendar
* FIX: remove postId and move ICS to frontend
PostId is not necessary and will make the solution more generic for dates which doesn't belong to a specific post.
Also, ICS file can be generated in JavaScript to avoid calling backend.
In most cases, these links are handled in JavaScript, so the `href` and `target` are not used. However, when the `link-to-post` refers to a post which is not currently loaded in the DOM (e.g. it is the OP), then the href is used, and we need to add a `target` to prevent page navigation within the embed iframe.
It allows saving local date to calendar.
Modal is giving option to pick between ics and google. User choice can be remembered as a default for the next actions.
We don't need no stinkin' denormalization! This commit ignores
the topic_id column on bookmarks, to be deleted at a later date.
We don't really need this column and it's better to rely on the
post.topic_id as the canonical topic_id for bookmarks, then we
don't need to remember to update both columns if the bookmarked
post moves to another topic.
This was problematic if something like SCSS file throws an error as the
app would tell Ember CLI to bootstrap as if everything is fine and not
display the error.
The fix is to only hijack the rendering at the end of the template
instead of the beginning.
This commit updates the RSS post content to use email formatting. Many
plugins are using the `reduce_cooked` method to format content that is
not displayed outside of Discourse application. Using email formatting
also strips the secure media and various other things that is only meant
for Discourse client side application.
The modification date should always be a meta tag to make this less confusing. Especially for imported posts.
That's more in line with how the rest of Discourse presents post dates.
This adds an optional ENV variable, `EMBER_CLI_PROD_ASSETS`. If truthy,
compiling production assets will be done via Ember CLI and will replace
the assets Rails would otherwise use.
And also move all the "top topics by period" routes to query string param.
/top/monthly => /top?period=monthly
/c/:slug/:id/l/top/monthly => /c/:slug/:id/l/top?period=monthly
/tag/:slug/l/top/daily => /tag/:slug/l/top?period=daily (new)
This PR makes several changes to the group SMTP email contents to make it look more like a support inbox message.
* Remove the context posts, they only add clutter to the email and replies
* Display email addresses of staged users instead of odd generated usernames
* Add a "please reply above this line" message to sent emails
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.
The `ember_jquery` bundle contains production builds of Ember and jQuery
which doesn't work with tests. This commits introduces a new
`theme_qunit_vendor` bundle which is copy of the `vendor` bundle but
doesn't contain `ember_jquery`.
This commit is a partial revert of
409c8585e4
In Ember CLI addons get put into the vendor bundle, as opposed to their
own bundle like we're doing in the Rails app. We never use pretty-text
without our vendor bundle so this should have no difference on
performance.
We need to keep the pretty-text bundle for server side cooking.
In Ember CLI, the vendor bundler includes Ember/jQuery, so this brings
our app closer to that configuration.
We have a couple pages (Reset Password / Confirm New Email) where we need
`ember_jquery` without vendor so the file still exists for those cases.
Some themes/components depend on plugins, and it would be impossible to write tests for those themes without installing/loading the plugins they depend on.
We really want to encourage all developers to use Ember CLI for local
development and testing. This will display an error page if they are not
with instructions on how to start the local server.
To disable it, you can set `NO_EMBER_CLI=1` as an ENV variable
* FEATURE: Small improvements to the topic list embed
- Ability to wrap the list in a custom class so you can styles different
lists using specific CSS
- Adds a topic link to the thumbnail when using the complete template
* FIX: Be more strict about allowed chars in class name
This commit allows site admins to run theme tests in production via a new `/theme-qunit` route. When you visit `/theme-qunit`, you'll see a list of the themes/components installed on your site that have tests, and from there you can select a theme or component that you run its tests.
We also have a new rake task `themes:install_and_test` that can be used to install a list of themes/components on a temporary database and run the tests of the themes/components that are installed. This rake task can be useful when upgrading/deploying a Discourse instance to make sure that the installed themes/components are compatible with the new Discourse version being deployed, and if the tests fail you can abort the build/deploy process so you don't end up with a broken site.
This commit allows site admins to run theme tests in production via a new `/theme-qunit` route. When you visit `/theme-qunit`, you'll see a list of the themes/components installed on your site that have tests, and from there you can select a theme or component that you run its tests.
We also have a new rake task `themes:install_and_test` that can be used to install a list of themes/components on a temporary database and run the tests of the themes/components that are installed. This rake task can be useful when upgrading/deploying a Discourse instance to make sure that the installed themes/components are compatible with the new Discourse version being deployed, and if the tests fail you can abort the build/deploy process so you don't end up with a broken site.
* DEV: Give a nicer error when `--proxy` argument is missing
* DEV: Improve Ember CLI's bootstrap logic
Instead of having Ember CLI know which URLs to proxy or not, have it try
the URL with a special header `HTTP_X_DISCOURSE_EMBER_CLI`. If present,
and Discourse thinks we should bootstrap the application, it will
instead stop rendering and return a HTTP HEAD with a response header
telling Ember CLI to bootstrap.
In other words, any time Rails would otherwise serve up the HTML for the
Ember app, it stops and says "no, you do it."
* DEV: Support asset filters by path using a new options object
Without this, Ember CLI's bootstrap would not get the assets it wants
because the path it was requesting was different than the browser path.
This adds an optional request header to fix it.
So far this is only used by the styleguide.
This commit allows themes and theme components to have QUnit tests. To add tests to your theme/component, create a top-level directory in your theme and name it `test`, and Discourse will save all the files in that directory (and its sub-directories) as "tests files" in the database. While tests files/directories are not required to be organized in a specific way, we recommend that you follow Discourse core's tests [structure](https://github.com/discourse/discourse/tree/master/app/assets/javascripts/discourse/tests).
Writing theme tests should be identical to writing plugins or core tests; all the `import` statements and APIs that you see in core (or plugins) to define/setup tests should just work in themes.
You do need a working Discourse install to run theme tests, and you have 2 ways to run theme tests:
* In the browser at the `/qunit` route. `/qunit` will run tests of all active themes/components as well as core and plugins. The `/qunit` now accepts a `theme_name` or `theme_url` params that you can use to run tests of a specific theme/component like so: `/qunit?theme_name=<your_theme_name>`.
* In the command line using the `themes:qunit` rake task. This take is meant to run tests of a single theme/component so you need to provide it with a theme name or URL like so: `bundle exec rake themes:qunit[name=<theme_name>]` or `bundle exec rake themes:qunit[url=<theme_url>]`.
There are some refactors to how Discourse processes JavaScript that comes with themes/components, and these refactors may break your JS customizations; see https://meta.discourse.org/t/upcoming-core-changes-that-may-break-some-themes-components-april-12/186252?u=osama for details on how you can check if your themes/components are affected and what you need to do to fix them.
This commit also improves theme error handling in Discourse. We will now be able to catch errors that occur when theme initializers are run and prevent them from breaking the site and other themes/components.
This commit allows themes and theme components to have QUnit tests. To add tests to your theme/component, create a top-level directory in your theme and name it `test`, and Discourse will save all the files in that directory (and its sub-directories) as "tests files" in the database. While tests files/directories are not required to be organized in a specific way, we recommend that you follow Discourse core's tests [structure](https://github.com/discourse/discourse/tree/master/app/assets/javascripts/discourse/tests).
Writing theme tests should be identical to writing plugins or core tests; all the `import` statements and APIs that you see in core (or plugins) to define/setup tests should just work in themes.
You do need a working Discourse install to run theme tests, and you have 2 ways to run theme tests:
* In the browser at the `/qunit` route. `/qunit` will run tests of all active themes/components as well as core and plugins. The `/qunit` now accepts a `theme_name` or `theme_url` params that you can use to run tests of a specific theme/component like so: `/qunit?theme_name=<your_theme_name>`.
* In the command line using the `themes:qunit` rake task. This take is meant to run tests of a single theme/component so you need to provide it with a theme name or URL like so: `bundle exec rake themes:qunit[name=<theme_name>]` or `bundle exec rake themes:qunit[url=<theme_url>]`.
There are some refactors to internal code that's responsible for processing themes/components in Discourse, most notably:
* `<script type="text/discourse-plugin">` tags are automatically converted to modules.
* The `theme-settings` service is removed in favor of a simple `lib` file responsible for managing theme settings. This was done to allow us to register/lookup theme settings very early in our Ember app lifecycle and because there was no reason for it to be an Ember service.
These refactors should 100% backward compatible and invisible to theme developers.
browser-update script does not work correctly in some very old browsers
because the contents of <noscript> is not accessible in JavaScript.
For these browsers, the server can display the crawler page and add the
browser update notice.
Simply loading the browser-update script in the crawler view is not a
solution because that means all crawlers will also see it.
This fixes the following error: "Uncaught ReferenceError: I18n is not defined"
The alternative would be to add `locales/#{I18n.locale}`, but the pages do not use any JS.
The 'Discourse SSO' protocol is being rebranded to DiscourseConnect. This should help to reduce confusion when 'SSO' is used in the generic sense.
This commit aims to:
- Rename `sso_` site settings. DiscourseConnect specific ones are prefixed `discourse_connect_`. Generic settings are prefixed `auth_`
- Add (server-side-only) backwards compatibility for the old setting names, with deprecation notices
- Copy `site_settings` database records to the new names
- Rename relevant translation keys
- Update relevant translations
This commit does **not** aim to:
- Rename any Ruby classes or methods. This might be done in a future commit
- Change any URLs. This would break existing integrations
- Make any changes to the protocol. This would break existing integrations
- Change any functionality. Further normalization across DiscourseConnect and other auth methods will be done separately
The risks are:
- There is no backwards compatibility for site settings on the client-side. Accessing auth-related site settings in Javascript is fairly rare, and an error on the client side would not be security-critical.
- If a plugin is monkey-patching parts of the auth process, changes to locale keys could cause broken error messages. This should also be unlikely. The old site setting names remain functional, so security-related overrides will remain working.
A follow-up commit will be made with a post-deploy migration to delete the old `site_settings` rows.
This cookie is only used during login. Having it persist after that can
cause some unusual behavior, especially for sites with short session
lengths.
We were already deleting the cookie following a new signup, but not for
existing users.
This commit moves the cookie deletion logic out of the erb template, and
adds logic and tests to ensure it is always deleted consistently.
Co-authored-by: Jarek Radosz <jradosz@gmail.com>
CSS are blocking resources, so keeping them below JS delays
rendering of the page. CSS should be loaded ASAP.
This change speeds up first contentful paint by 0.2s on localhost.
The slower the device, the bigger the difference could be.
Per Google, sites are encouraged to upgrade from Universal Analytics v3 `analytics.js` to v4 `gtag.js` for Google Analytics tracking. We're giving admins the option to stay on the v3 API or migrate to v4. Admins can change the implementation they're using via the `ga_version` site setting. Eventually Google will deprecate v3, but our implementation gives admins the choice on what to use for now.
We chose this implementation to make the change less error prone, as many site admins are using custom events via the v3 UA API. With the site stetting defaulted to `v3_analytics`, site analytics won't break until the admin is ready to make the migration.
Additionally, in the v4 implementation, we do not enable automatic pageview tracking (on by default in the v4 API). Instead we rely on Discourse's page change API to report pageviews on transition to avoid double-tracking.
Per Google, sites are encouraged to upgrade from `analytics.js` to `gtag.js` for Google Analytics tracking. This commit updates core Discourse to use the new `gtag.js` API Google is asking sites to use. This API has feature parity with `analytics.js` but does not use trackers.
DEV: Replace instances of Discourse.base_uri with Discourse.base_path
This is clearer because the base_uri is actually just a path prefix. This continues the work started in 555f467.
A first step to adding automatic dark mode color scheme switching. Adds a new SCSS file at `color_definitions.scss` that serves to output all SCSS color variables as CSS custom properties. And replaces all SCSS color variables with the new CSS custom properties throughout the stylesheets.
This is an alpha feature at this point, can only be enabled via console using the `default_dark_mode_color_scheme_id` site setting.
There was a bug that even when `email_digest` was set to false but
`digest_after_minutes` was positive, we were not displaying correct
status.
In addition, the message is improved when the user is unsubscribed +
unsubscribe from all is hidden.
* DEV: To be pedantic, there is more than EMBER in there now
* DEV: Use less globals. Have `Discourse` start in an initializer
* DEV: Remove another global
This reverts commit 20780a1eee.
* SECURITY: re-adds accidentally reverted commit:
03d26cd6: ensure embed_url contains valid http(s) uri
* when the merge commit e62a85cf was reverted, git chose the 2660c2e2 parent to land on
instead of the 03d26cd6 parent (which contains security fixes)
