Capistrano deploy fails due to missing manifest file when using assets prefix - ruby-on-rails-3

Question

I've just set up a Capistrano deploy for our application and I keep running into this error:
* executing ["ls /path/to/app/shared/assets/manifest*"]
servers: ["web03"]
[web03] executing command
[err :: web03] ls: /path/to/app/shared/assets/manifest*
[err :: web03] : No such file or directory
If I manually create a manifest file with touch /path/to/app/shared/assets/manifest.yml, the deploy script works fine. However, this feels all sorts of sketchy.
I've googled the heck out of this and the most I can gather is that the manifest file it's looking for is a product of the asset pipeline. I checked and I do, in fact, have the pipeline enabled (config.assets.enabled = true), so I'm at a loss.
Could someone please help me understand 1) what this manifest file is and how it's created; and 2) why isn't one being created for my application?
Update: I think I'm closing in on the answer and I think it has something to do with this line:
config.assets.prefix = "/some_other_path"
We needed to rename the "asset" path because we have Asset objects in our system and I'm guessing Cap might be getting confused because of it. Any suggestions?

Answer 1

My suspicion was right: this was a problem with the renamed asset directory. Cap didn't know to look in public/some_other_path instead of public/assets.
In other words, because this line is in my application.rb:
config.assets.prefix = "some_other_path"
I had to add this line to my deploy.rb:
set :assets_prefix, "some_other_path"
Then, Cap knows where to look for a manifest, copies it into shared/assets, and finishes correctly.
It'd be handy to have the deploy.rb reference the config variable instead of having to hard-code the path a second time, but that's outside the scope of this question.

Answer 2

if you configure with the aws, here it should be...
appname/config/environments/production.rb
config.action_controller.asset_host = "//#{ENV['FOG_DIRECTORY']}.s3.amazonaws.com"
config.assets.prefix = "/#{ENV['APP_NAME']}/assets"
appname/config/deploy.rb
...
set :keep_releases, 5
set :assets_prefix, ->{ "#{fetch(:application)}/assets" }
set :whenever_identifier, -> { "#{fetch(:application)}_#{fetch(:stage)}" }
...