Question

I have created grails application and uploaded it in heroku.
If I use ‘heroku scale web=1’ everything looks OK. But if I run ‘heroku scale web=2’, some static resources disappear.
From logs I can figure out, that all static resources from web.2 dyno are missing. But this dyno is started without any errors.

How can I resolve this problem?

Answer 1

https://github.com/grails-plugins/grails-resources/pull/11

According to the owner of the resources plugin, Marc Palmer, they’re ignoring a check for old references to static resources.

So, this manifests itself as a load balancing issue that you would have on any system if you’re not using sticky load balancing (which is the case with Heroku). Here’s what’s happening in the Heroku case:

1. Request comes into someapp.com
2. index.gsp is served from app server 1, web.1
   index.gsp contains
3. The resources plugin generates a mapping from /static/js/resource.js to /js/resource.js on web.1
4. The client makes a request for /static/js/resource.js
5. The request is routed to a different app server, web.2
6. /static/js/resource.js has not been mapped on web.2 and 404s

From my research, the best practice is to declare your resources in a resources file.

See the following:

http://grails-plugins.github.com/grails-resources/guide/3.%20Declaring%20resources.html

This will tell the app server at boot time that a resource exists up front, avoiding the adhoc loading process.

For example, as in my previous email, a MyResources.groovy would look like:

modules = { 
  application { 
    resource url:'js/application.js' 
    resource url:'js/ui.geo_autocomplete.js' 
  } 
}

So, you can use either of the two methods — explicitly specify resources, or use adhoc loading (add the following to your Config.groovy: )

grails.resources.adhoc.includes = [] 
grails.resources.adhoc.excludes = ["*"]

It essentially disables adhoc resource processing.