Gem::MissingSpecError for plugin gem dependency

Dev
1

I’ve created some plugin for Discourse and added a gem dependency in plugin.rb like this:

gem 'faraday-multipart', '1.1.0', require_name: 'faraday/multipart'

then referenced this plugin in app.yml and performed launcher rebuild app and received such error:

...
I, [2025-02-10T15:54:07.383295 #1]  INFO -- : > cd /var/www/discourse && su discourse -c 'bundle exec rake db:migrate'
rake aborted!
Gem::MissingSpecError: Could not find 'multipart-post' (~> 2.0) among 233 total gem(s) (Gem::MissingSpecError)
Checked in 'GEM_PATH=/var/www/discourse/vendor/bundle/ruby/3.3.0:/var/www/discourse/plugins/discourse-watermark/gems/3.3.6' at: /var/www/discourse/plugins/discourse-watermark/gems/3.3.6/specifications/faraday-multipart-1.1.0.gemspec, execute `gem env` for more information
/var/www/discourse/lib/plugin_gem.rb:25:in `load'
/var/www/discourse/lib/plugin/instance.rb:858:in `gem'
/var/www/discourse/plugins/discourse-watermark/plugin.rb:10:in `activate!'
/var/www/discourse/lib/plugin/instance.rb:801:in `instance_eval'
/var/www/discourse/lib/plugin/instance.rb:801:in `activate!'
/var/www/discourse/lib/discourse.rb:348:in `block in activate_plugins!'
/var/www/discourse/lib/discourse.rb:345:in `each'
/var/www/discourse/lib/discourse.rb:345:in `activate_plugins!'
/var/www/discourse/config/application.rb:233:in `block in <class:Application>'
/var/www/discourse/lib/plugin.rb:6:in `initialization_guard'
/var/www/discourse/config/application.rb:233:in `<class:Application>'
/var/www/discourse/config/application.rb:75:in `<module:Discourse>'
/var/www/discourse/config/application.rb:74:in `<top (required)>'
/var/www/discourse/Rakefile:7:in `<top (required)>'
/var/www/discourse/vendor/bundle/ruby/3.3.0/gems/rake-13.2.1/exe/rake:27:in `<top (required)>'
/usr/local/bin/bundle:25:in `load'
/usr/local/bin/bundle:25:in `<main>'
...
I, [2025-02-10T15:54:09.620121 #1]  INFO -- : gem install faraday-multipart -v 1.1.0 -i /var/www/discourse/plugins/discourse-watermark/gems/3.3.6 --no-document --ignore-dependencies --no-user-install
Successfully installed faraday-multipart-1.1.0
1 gem installed

I, [2025-02-10T15:54:09.625734 #1]  INFO -- : Terminating async processes
...
FAILED
...

So it fails on db:migrate step, although later in logs it says that the gem faraday-multipart is installed successfully. My theory is that db:migrate is running before the gem is installed, but probably I’m missing something since discourse has a lot of plugins with gem dependencies and they work somehow.

2 Likes
2

Unfortunately our plugin gem helper doesn’t automatically install sub-dependencies, so you’ll need to install those manually.

Here’s an example of a plugin which uses faraday-multipart:

2 Likes
3

Oh, thank you for such quick answer! I even haven’t noticed that it’s a sub-dependency :sweat_smile: I’ll try.
UPD. Yes, this worked:

gem 'multipart-post', '2.4.1', require_name: 'multipart/post'
gem 'faraday-multipart', '1.1.0', require_name: 'faraday/multipart'

Important: sub-dependencies should go before the original dependency, eg. multipart-post must be before faraday-multipart, as in your example.

2 Likes
4

This is a complete mini-game in Discourse development :wink:

(moved to Dev)

2 Likes