capistrano on_rollback not being called - ruby-on-rails

Question

I'm using capistrano v2 for a Rails 3.2 I have a bundler task in my deploy.rb like so;
# Bundler tasks
namespace :bundler do
desc "Create a symlink"
task :create_symlink, :roles => :app do
shared_dir = File.join(shared_path, 'bundle')
release_dir = File.join(release_path, '.bundle')
run("mkdir -p #{shared_dir} && ln -s #{shared_dir} #{release_dir}")
end
desc "Install required gems"
task :install, :roles => :app do
puts "New Release"
run "cd #{release_path} && #{bundle_path} install"
on_rollback do
if previous_release
puts "Rollback"
run "cd #{previous_release} && #{bundle_path} install"
else
logger.important "no previous release to rollback to, rollback of bundler:install skipped"
end
end
end
desc "Run bundler on new release"
task :bundle_new_release, :roles => :db do
bundler.create_symlink
bundler.install
end
end
after "deploy:update_code", "bundler:bundle_new_release"
after "deploy:rollback:revision", "bundler:install"
When I run cap deploy:rollback it doesn't run the the on_rollback code it tries to run the cd {release_path}.
I got this example from http://kazjote.eu/2010/08/04/bundler-and-capistrano-the-right-way.

Answer 1

Since you didn't give any logs, I can't say for sure if deploy:rollback is deploying the previous version as it should, however you're confusing deploy:rollback (a task), with on_rollback (a hook).
on_rollback would be called only if the task :install failed. However, I also believe you need to define a transaction for the on_rollback hook to actually fire (and possibly have to make the on_rollback definition before your 'run "cd...')
deploy:rollback should run your deploy tasks with the previous successful release.
I found a simpler example here:
http://pedz-bits.blogspot.com/2012/09/capistrano-errors-ensure-and-onrollback.html
namespace :fun do
desc "Sample showing rescue, ensure, and on_rollback inside a transaction"
task :stuff, :roles => :app do
transaction do
on_rollback { logger.debug "my rollback" }
begin
logger.debug "main"
# Either run or run_locally will work the same
# run_locally "false"
run "false"
rescue => e
logger.debug "rescue #{e.class}"
raise e
ensure
logger.debug "ensure"
end
end
end
end
Command output:
cap fun:stuff
* executingD `fun:stuff'
** transaction: start
* main
* executingB "false"
servers: ["condor.austin.ibm.com"]
[condor.austin.ibm.com] executingA command
command finished in 771ms
* rescue Capistrano::CommandError
* ensure
*** [fun:stuff] rolling back
* my rollback
failed: "bash -l -c 'false'" on condor.austin.ibm.com
Notes
on_rollback executes only if the error happens while a transaction is active.
on_rollback must also be defined within the transaction.
raise e to make sure task exits with an error or higher level process will assume it completed successfully.
ensure works as you expect.