DISCOURSE_CDN_URL breaks rebuild/restore

EDIT: Well, it took me 18 hours, but it seems that defining DISCOURSE_CDN_URL keeps (at least) this site from rebuilding and/or functioning after a restore. I guess the next thing to test is doing a build without DISCOURSE_CDN_URL and then cranking up the container with the ENV var set.

What I knew before

I had this problem yesterday but thought it went away, but it turns out that I restored a month-old database. Restoring the recent database kills the site.

I was able to build the site from scratch, so it’s not a problem with the code or any standard plugins. BUT after I have restored the database, the site is down, and I can’t do a rebuild, even if I delete the database, so I guess the problem is something in a file that gets read when it’s compressing the javascript.

I tried removing all of the background: image-url in onebox.scss, which allowed the site to rebuild, but the display is all screwed up, so those errors are a symptom rather than the cause of the problem.

I get errors like the below in the rails log after restoring the database (and files) or when rebuilding.

I, [2019-12-22T21:21:25.532604 #1]  INFO -- : > cd /var/www/discourse && su discourse -c 'bundle exec rake db:migrate'
NOTE: Inheriting Faraday::Error::ClientError is deprecated; use Faraday::ClientError instead. It will be removed in or after version 1.0
Faraday::Error::ClientError.inherited called from /var/www/discourse/plugins/discourse-github/gems/2.6.5/gems/octokit-4.14.0/lib/octokit/middleware/follow_redirects.rb:14.
> Seeding dark and light themes
[SassC::FunctionsHandler] undefined method `protocol' for nil:NilClass
rake aborted!
Discourse::ScssError: Error: error in C function image-url: undefined method `protocol' for nil:NilClass
        on line 90 of app/assets/stylesheets/common/base/onebox.scss, in function `image-url`
        from line 90 of app/assets/stylesheets/common/base/onebox.scss, in mixin `onebox-favicon`
        from line 110 of app/assets/stylesheets/common/base/onebox.scss
        from line 34 of app/assets/stylesheets/common.scss
        from line 1 of desktop.scss
>>     background: image-url("favicons/#{$image}.png") no-repeat 0% 50%;

/var/www/discourse/lib/stylesheet/manager.rb:183:in `rescue in compile'
/var/www/discourse/lib/stylesheet/manager.rb:171:in `compile'
/var/www/discourse/lib/stylesheet/manager.rb:80:in `block (2 levels) in stylesheet_details'
/var/www/discourse/lib/stylesheet/manager.rb:66:in `each'
/var/www/discourse/lib/stylesheet/manager.rb:66:in `block in stylesheet_details'
/var/www/discourse/lib/stylesheet/manager.rb:64:in `synchronize'
/var/www/discourse/lib/stylesheet/manager.rb:64:in `stylesheet_details'
/var/www/discourse/lib/stylesheet/manager.rb:34:in `stylesheet_data'
/var/www/discourse/app/models/theme.rb:280:in `block in refresh_message_for_targets'
/var/www/discourse/app/models/theme.rb:279:in `map'
/var/www/discourse/app/models/theme.rb:279:in `refresh_message_for_targets'
/var/www/discourse/app/models/theme.rb:267:in `notify_theme_change'
/var/www/discourse/app/models/theme.rb:275:in `notify_theme_change'
/var/www/discourse/app/models/theme.rb:61:in `block in <class:Theme>'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.1/lib/active_support/callbacks.rb:429:in `instance_exec'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.1/lib/active_support/callbacks.rb:429:in `block in make_lambda'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.1/lib/active_support/callbacks.rb:239:in `block in halting_and_conditional'

@pfaffman I’ve just stumbled across this exact same issue after battling through my other problems when trying to set up S3. Did you ever find out what was causing this?

Fixed it. Make sure you prepend your CDN url with http:// :facepalm:

So instead of DISCOURSE_CDN_URL=your-cdn-url.com it should be DISCOURSE_CDN_URL=http://your-cdn-url.com.

Only 2 hours wasted debugging it :smiley:


Hmm can we add some kind of warning here @eviltrout so people don’t run into this in the future?


This will pop up a warning if you don’t add a protocol:


But bozos (like me) who do this with ENV variables will still have trouble. Is there a downside to printing the warning and prepending https://?

GlobalSetting is the object that takes your ENV variables into Discourse, so if you do it that way the warning should also appear.


I too feel pretty silly for falling into this trap! :laughing:

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If I’m remembering correctly, I lost 18 hours on it during what was supposed to be a Christmas break. :frowning_face:

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