Asset precompilation woes

[bjeanes]

Currently config.assets.initialize_on_precompile is set to true (the default). This means, if you want to precompile assets prior to a deployment (e.g. creating a war file, deploying to Heroku, or just doing the work once before sending out to many servers), you need to have access to the production DB.

Usually, to counter this, one can set RAILS_ENV=development before running the precompilation rake task. However, in the case of Squash, "flot/excanvas.js" is added to config.assets.precompile only in config/environments/production.rb resulting in a ActionView::Template::Error (flot/excanvas.js isn't precompiled) error at runtime in production.

So, there are two ways out of this that I see. I'm happy to issue a pull request for either direction, I just wanted some input first in case there is a preferred route:

1. Move config.assets.precompile << 'flot/excanvas.js from production.rb to application.rb so it is effective in all compilation environments (i.e. allowing precompilation with RAILS_ENV=development)
2. Set config.assets.initialize_on_precompile = false so that a DB connection is not formed. This has other issues if any of the assets access certain classes or constants at compile time (e.g. ERB assets).

For option 2, one error that already pops up is uninitialized constant Ping due to a lot of assumed requires not happening. Things like this would need to be resolved.

[bjeanes]

Seems like option 2 would be out:

rake aborted!
uninitialized constant Squash::Configuration
  (in /Users/bjeanes/Code/squash/web/lib/assets/javascripts/configure_squash_client.js.erb)
/Users/bjeanes/Code/squash/web/lib/assets/javascripts/configure_squash_client.js.erb:15:in `evaluate_source'

[RISCfuture]

Unless I'm mistaken, option 2 restricts the flexibility of people's deploy situations. Some people will want to precompile their assets locally, and others will want to do it on the target. And no matter what environments initialize_on_precompile is set on, we're always going to want to add excanvas to that list. So it makes sense to put that in application.rb to me.

[bjeanes]

Makes sense... that's what I did locally too, so I'm glad you agree. I'll send a PR shortly.

[bjeanes]

@RISCfuture I just added a commit that solves the issue for me locally and allows me to run rake assets:precompile:all RAILS_ENV=development, bundle it up in a war file and run. There are few other .war related things I'll be PR-ing shortly, too.

[gamafranco]

Note, this is also breaking deploys on heroku. For heroku, we need to either compile localy or set config.assets.initialize_on_precompile = false.

Plus IMHO, for deploy, it shouldn't be mandatory to setup and run the app on development.

[bjeanes]

@gamafranco actually, for Heroku I believe you can also follow https://devcenter.heroku.com/articles/labs-user-env-compile to have it "just work"

[gamafranco]

Hi bjeanes,

Thanks for the tip, I don't see how that might help. Heroku dones't allow database connections at asset compile time, so config.assets.initialize_on_precompile needs to be false. And that raises the problems you identified above.

Thanks.

[bjeanes]

@gamafranco it will help because that's the point of that lab feature. It will provide the database details at "compilation" time such that your rake task will know which database to connect to. Search that page for "assets:precompile"

[bjeanes]

@RISCfuture bump. Commit attached that solves problem using method 1.