Collude - a collaborative text editor for Discourse

Collude is a collaborative text editor for Discourse, written using EasySync, the same underlying algorithm used in Etherpad :nerd_face:

Give it a look

Check out a video demo, or give it a whirl on my test instance.

Give it a try

NOTE: This project is decidedly beta at the moment, and I am posting here in order to garner some willing souls to help me test it out and let me know what’s rough and what I should improve next.

To install, follow the normal plugin installation instructions.

As an admin, create a post, and click ‘Allow collaborative editing’ under the wrench menu

Now, users with sufficient trust level (default is 2, configurable in the settings), will be able to click ‘Collaborate’ and get an editor to modify the post in real time.

Configurable settings:

Learn more, help out, or give feedback

Visit the github repo, or ping me @gdpelican here on meta.



This looks pretty cool! I had a quick skim of the repo and can’t see any external dependencies - is that correct? It just implements the ‘EasySync’ algorithm in Discourse?

1 Like

There aren’t any external dependencies, no. The linked PDF is essentially a fairly detailed technical description of how Etherpad does their collaborative editing, which I’ve implemented in the plugin, the guts being here on the frontend, and here on the backend. (The paper does an excellent job of obscuring how simple the implementation actually is, but I couldn’t find a better one, and of course Etherpad’s source has a bunch of other stuff going on, so it’s not the greatest thing to look at for an MVP type implementation).

It’s probably not perfectly to the letter of the algorithm, notably the bits about merging otherwise incompatible diffs, but I kinda found those to be somewhat rare corner cases, which could be pretty easily remedied by the users involved even if it doesn’t follow what should happen exactly. For example, the paper suggests that if two users submit diffs like this at the same time:

(baseball -> below) + (baseball -> basil) == besiow

whereas my implementation might output

(baseball -> below) + (baseball -> basil) == belowasil



Awesome! I love this. Thanks for creating it! :sunflower:

Some suggestions:

  • when editing collaboratively in the composer, it is not clear how to stop editing. it’s the “minimize the composer panel” button in the top right corner of the composer which in this case makes it go away instead of minimizing. Maybe change the helper text to say “stop editing”. Or add a button where REPLY/cancel normally would be to say STOP EDITING or some such.
  • it would be helpful to know who has collaboratively edited a particular post, as well as who is currently in there collaboratively editing right now. Could the existing “replying…” feature potentially be utilized for this? e.g, display avatars and “editing…” in the composer and below the post.
  • it would also be helpful to know who contributed what to the collaboratively edited text. Not sure how to handle this - I liked how etherpad used to let you choose a color for yourself, which would identify your contributions. Google docs lets you see who’s editing and where their cursor is in the doc.
  • I think the “collaborate” button could be changed to “edit” but using the same icon and helper text… I think it’s clearer and in many cases there may not be more than one person around to edit anyway.
  • a different and more scalable way to allow/disallow collaboration may be to add the collaborate icon to the post menu, with “start collaborating” (not enabled) and “stop collaborating” (enabled) as options. Only visible to those allowed to start/stop collaboration.
  • a category setting to enable collaborative editing might be preferable, along the lines of wiki.

Great, thanks for the feedback! Some responses:

I’ve added this (It was a bug that it wasn’t there, heh :sweat_smile:

I agree with this a lot and will be thinking hard over the next wee while on the best way to implement it; it’s tricky, but essential in my opinion. Displaying cursors feels fragile and crazy to me (I think you have to absolutely position an indicator div based on a cursor position sent over the wire), so I’m currently thinking on the best way to store information in the diff structure about the author of each fragment (which I think should allow Etherpad-style background coloring), while trying to keep it acceptably scalable. The answer to ‘can the existing replying functionality be used’ is no :slight_smile:

I’ve done this as well, as well as hiding the ‘edit’ and ‘wiki’ functionality when a document is realtime-editable (I think of this as a per-post replacement for those functions, which are already mutually exclusive)

I disagree with this one; when building features like this I often think of them as ‘analogous’ with some other feature in the core codebase (retort is analogous to ‘like’, for example), and attempt to design the experience to be parallel to that. For this feature, that’s ‘wiki’ (ie, if you’re thinking about doing this to a post, you would probably also consider wiki-fying it), meaning those options want to be together in the interface.


I’d like to do this, but the core codebase isn’t very extensible to adding category settings at the moment (the one for Retort is a pretty hacky workaround that I’d like to avoid repeating), and so would require changes to core - and I’ve had trouble getting core to accept changes to accommodate plugins. So I’m very hesitant to make plugin features which depend on changes to core, because even very low-risk requests get rejected too often.


I like the fixes - thank you! I can see this being very useful in my community, especially when we are in one of our many webinars or video conference calls and taking notes collaboratively.

Bummer about not being able to replicate the “replying…” feature. That way we’d know it’s worth jumping in to collaborate, and once in collaborating we’d know who’s collaborating with us.

Has anyone experienced problems installing this plugin? Is it stable? I’d like to try it in my community as soon as it’s reasonably stable. :rocket:

I’m currently installing it. I will report soon :slight_smile: If others already use it though, I’m interested to know as well.

First Report

Installation goes well. I tried to create a new topic and turned it into a collaborative editor using the topic menu option in the wrench. It worked. Then I invited my companion to join the topic and edit. But here there’s a bug: as she started editing, the existing content of the pad disappeared. I tried to edit as well, but our edits would cancel each other.

I’ve seen this with early Etherpad Lite where the pointer would flicker as other people would edit, jumping from your line to their line. I guess something similar is happening here, that the pointers are not handled well. @gdpelican did you encounter this bug?

Note that I have the Embed Etherpad Lite pads into Discourse plugin installed as well, so they might be conflicting.

Interestingly, although the content was removed from the editor, it didn’t save.

1 Like

Can you point me to the instance where this is happening?

It’s a private topic but I can invite you there.

Here, I made a public one.

Note that when I click “Edit”, I get an empty post although the sentence “This is a collaborative editor.” is written in the topic’s first post.

Let me run rake multisite:migrate since a log is complaining about it…

OK, I fixed it for the main instance, but another instance on Multisite cannot have it. I wonder whether it comes from a mistake I made with /shared permissions… I rebuilt all containers, so it should work now.

On the failing instance I get

ActiveRecord::StatementInvalid (PG::UndefinedColumn: ERROR: column "collusion" does not exist


Clearing Active Record cache, this can happen if schema changed while site is running or in a multisite various databases are running different schemas. Consider running rake multisite:migrate. 

Hm, I tried making an account on the linked site, but it didn’t work for me; I managed to make one on the site it redirected me to, but clicking ‘login’ on gives me this:

I’ll shift the migration around to the official method to see if that clears up the migration error; of course I didn’t test it on a multisite setup. In the meantime you can run the following to get the migration to go:

require Rails.root.join('plugins', 'collude', 'app', 'migrations', 'add_collusions')

This must be because I disallowed Gmail on this instance.

Thanks! Do you happen to remember how to run this in multisite mode? I keep forgetting this.

Nah, it was a straight email signup :slight_smile:

OK, so I ran this… Then I tried again and got:

NameError (undefined local variable or method `collusion' for #<Collusion:0x00007fc71730e220>) /var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activemodel-5.2.0/lib/active_model/attribute_methods.rb: 

/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activemodel-5.2.0/lib/active_model/attribute_methods.rb:430:in `method_missing'
/var/www/discourse/plugins/collude/app/models/collusion.rb:13:in `block (2 levels) in collusion_accessor'
/var/www/discourse/plugins/collude/app/models/collusion.rb:42:in `user='
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activemodel-5.2.0/lib/active_model/attribute_assignment.rb:51:in `public_send'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activemodel-5.2.0/lib/active_model/attribute_assignment.rb:51:in `_assign_attribute'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activemodel-5.2.0/lib/active_model/attribute_assignment.rb:44:in `block in _assign_attributes'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activemodel-5.2.0/lib/active_model/attribute_assignment.rb:43:in `each'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activemodel-5.2.0/lib/active_model/attribute_assignment.rb:43:in `_assign_attributes'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/attribute_assignment.rb:23:in `_assign_attributes'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activemodel-5.2.0/lib/active_model/attribute_assignment.rb:35:in `assign_attributes'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/core.rb:314:in `initialize'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/inheritance.rb:66:in `new'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/inheritance.rb:66:in `new'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/persistence.rb:35:in `create'
/var/www/discourse/plugins/collude/app/models/collusion.rb:19:in `spawn'
/var/www/discourse/plugins/collude/app/controllers/collusions_controller.rb:26:in `create_collusion'
/var/www/discourse/plugins/collude/app/controllers/collusions_controller.rb:7:in `create'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_controller/metal/basic_implicit_render.rb:6:in `send_action'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/abstract_controller/base.rb:194:in `process_action'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_controller/metal/rendering.rb:30:in `process_action'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/abstract_controller/callbacks.rb:42:in `block in process_action'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.0/lib/active_support/callbacks.rb:132:in `run_callbacks'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/abstract_controller/callbacks.rb:41:in `process_action'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_controller/metal/rescue.rb:22:in `process_action'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_controller/metal/instrumentation.rb:34:in `block in process_action'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.0/lib/active_support/notifications.rb:168:in `block in instrument'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.0/lib/active_support/notifications/instrumenter.rb:23:in `instrument'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.0/lib/active_support/notifications.rb:168:in `instrument'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_controller/metal/instrumentation.rb:32:in `process_action'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_controller/metal/params_wrapper.rb:256:in `process_action'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activerecord-5.2.0/lib/active_record/railties/controller_runtime.rb:24:in `process_action'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/abstract_controller/base.rb:134:in `process'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionview-5.2.0/lib/action_view/rendering.rb:32:in `process'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-mini-profiler-1.0.0/lib/mini_profiler/profiling_methods.rb:104:in `block in profile_method'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_controller/metal.rb:191:in `dispatch'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_controller/metal.rb:252:in `dispatch'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/routing/route_set.rb:52:in `dispatch'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/routing/route_set.rb:34:in `serve'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/journey/router.rb:52:in `block in serve'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/journey/router.rb:35:in `each'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/journey/router.rb:35:in `serve'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/routing/route_set.rb:840:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-protection-2.0.3/lib/rack/protection/frame_options.rb:31:in `call'
/var/www/discourse/lib/middleware/omniauth_bypass_middleware.rb:24:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-2.0.5/lib/rack/tempfile_reaper.rb:15:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-2.0.5/lib/rack/conditional_get.rb:38:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-2.0.5/lib/rack/head.rb:12:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/http/content_security_policy.rb:18:in `call'
/var/www/discourse/lib/middleware/anonymous_cache.rb:214:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-2.0.5/lib/rack/session/abstract/id.rb:232:in `context'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-2.0.5/lib/rack/session/abstract/id.rb:226:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/middleware/cookies.rb:670:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.0/lib/active_support/callbacks.rb:98:in `run_callbacks'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/middleware/callbacks.rb:26:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/middleware/debug_exceptions.rb:61:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/middleware/show_exceptions.rb:33:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/logster-1.2.11/lib/logster/middleware/reporter.rb:31:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/railties-5.2.0/lib/rails/rack/logger.rb:38:in `call_app'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/railties-5.2.0/lib/rails/rack/logger.rb:28:in `call'
/var/www/discourse/config/initializers/100-quiet_logger.rb:16:in `call'
/var/www/discourse/config/initializers/100-silence_logger.rb:29:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/middleware/remote_ip.rb:81:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/actionpack-5.2.0/lib/action_dispatch/middleware/request_id.rb:27:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-2.0.5/lib/rack/method_override.rb:22:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rails_multisite-2.0.4/lib/rails_multisite/middleware.rb:24:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-2.0.5/lib/rack/sendfile.rb:111:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-mini-profiler-1.0.0/lib/mini_profiler/profiler.rb:285:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/message_bus-2.1.5/lib/message_bus/rack/middleware.rb:63:in `call'
/var/www/discourse/lib/middleware/request_tracker.rb:180:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/railties-5.2.0/lib/rails/engine.rb:524:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/railties-5.2.0/lib/rails/railtie.rb:190:in `public_send'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/railties-5.2.0/lib/rails/railtie.rb:190:in `method_missing'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-2.0.5/lib/rack/urlmap.rb:68:in `block in call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-2.0.5/lib/rack/urlmap.rb:53:in `each'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/rack-2.0.5/lib/rack/urlmap.rb:53:in `call'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/unicorn-5.4.0/lib/unicorn/http_server.rb:606:in `process_client'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/unicorn-5.4.0/lib/unicorn/http_server.rb:701:in `worker_loop'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/unicorn-5.4.0/lib/unicorn/http_server.rb:549:in `spawn_missing_workers'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/unicorn-5.4.0/lib/unicorn/http_server.rb:142:in `start'
/var/www/discourse/vendor/bundle/ruby/2.5.0/gems/unicorn-5.4.0/bin/unicorn:126:in `<top (required)>'
/var/www/discourse/vendor/bundle/ruby/2.5.0/bin/unicorn:23:in `load'
/var/www/discourse/vendor/bundle/ruby/2.5.0/bin/unicorn:23:in `<main>'

Still works fine on the main instance. (@gdpelican I invited you to the test topic.)

Seeing this, I suspect it might be related to SSO. But not: on another secondary instance, it fails but this one has no SSO configured.

Heh. @hellekin you are having the experience I am trying to avoid. :scream:

Sorry you are running into this and hope you get it resolved quickly!

1 Like

I’m just procrastinating really :wink:


Alright, I believe I’ve resolved the multi-site migrate issue. The topic you linked me to seems to be working fine @hellekin, although if you grant me TL2 on that instance (or set the trust level setting for Collude to 0), I can play with it a little.

Let me know if that gets you a bit further?


Did you commit changes to the plugin? In this case I can rebuild the container and see if that fixed the multisite migration.