There is a difference between "rake" and "bundle exec rake" and I need to understand it.

rubyonrails-talk
1

Hi Folks,

I think I need to understand this fundamental architectural question. I don’t know if it is a Ruby question or a Rails question, or a Ruby on Rails question.

Clearly I have multiple versions. Clearly I am supposed to have multiple versions. Clearly there is an accommodation for multiple versions. Clearly I don’t understand how this accommodation works.

Apparently, there are the “system” gems, and there are “bundle” gems, which are apparently controlled by my application. Presumable my application is always going to want to run in the context of the assembled gems collected for the purposes of the application. So, my first question is, how is this accomplished? Simple path search order?

For whatever reason, different versions are being selected in different contexts. I don’t know enough about how Ruby or Rails does things to understand this, but I have a simple example:

$ rake time:zones:local

rake aborted!

You have already activated rake 10.0.4, but your Gemfile requires rake 10.3.2. Prepending bundle exec to your command may solve this.

/var/www/vhost/todo.tryx.org/tracks/config/boot.rb:6:in `<top (required)>’

/var/www/vhost/todo.tryx.org/tracks/config/application.rb:1:in `<top (required)>’

/var/www/vhost/todo.tryx.org/tracks/Rakefile:5:in `<top (required)>’

(See full trace by running task with --trace)

$ bundle exec rake time:zones:local

  • UTC -08:00 *

Pacific Time (US & Canada)

Tijuana

Isn’t there some way to declare that the bundle context should be the default? In my case, I am running the Ruby on Rails application through Passenger, so I need to declare, “Use the bundle context” as the default. If somebody could point me in the direction of a manual that explains why all this works the way it does, I’d be appreciative.

Thanks for the help,

Chris.

2

Hi Folks,

I think I need to understand this fundamental architectural question. I don’t know if it is a Ruby question or a Rails question, or a Ruby on Rails question.

Clearly I have multiple versions. Clearly I am supposed to have multiple versions. Clearly there is an accommodation for multiple versions. Clearly I don’t understand how this accommodation works.

Apparently, there are the “system” gems, and there are “bundle” gems, which are apparently controlled by my application. Presumable my application is always going to want to run in the context of the assembled gems collected for the purposes of the application. So, my first question is, how is this accomplished? Simple path search order?

bundler makes sure only the gems (and the specific versions) listed in Gemfile.lock are loaded which avoids all sorts of dependency based problems. However if you just run rake, then the most recent version of rake is run. A few milliseconds boot.rb loads bundler, and if bundler finds that gems have been loaded that don’t match the version bundler wants to use then it aborts (since one a gem has been loaded you can’t unload it and load a different version)

When you run something with bundle exec, it ensures that only the gem versions in your Gemfile.lock are specified.

You can use http://mpapis.github.io/rubygems-bundler/ which ensures that the executables installed for rake etc. load bundler first. You can also use the bin stubs in your app’s bin folder .

I seem to recall the passenger knows to load bundler if a Gemfile is present - i don’t recall ever having to do something specific for this.

Fred

3

Hi Fred,

bundler makes sure only the gems (and the specific versions) listed in Gemfile.lock are loaded which avoids all sorts of dependency based problems. However if you just run rake, then the most recent version of rake is run. A few milliseconds boot.rb loads bundler, and if bundler finds that gems have been loaded that don’t match the version bundler wants to use then it aborts (since one a gem has been loaded you can’t unload it and load a different version)

When you run something with bundle exec, it ensures that only the gem versions in your Gemfile.lock are specified.

You can use http://mpapis.github.io/rubygems-bundler/ which ensures that the executables installed for rake etc. load bundler first. You can also use the bin stubs in your app’s bin folder .

Thanks very much for the explanation. Quite clear and now I think I understand to a much higher degree.

I seem to recall the passenger knows to load bundler if a Gemfile is present - i don’t recall ever having to do something specific for this.

Your recollections agree with other sources, so there is something mysterious on my machine, and I’m willing to blame SELinux. I should have dropped SELinux and tested, but it didn’t occur to me until I had already solved my problem by "gem install"ing the same version of rake and rack that the bundle had, thereby obviating the version problem – in this case.

Thanks for the help,

Chris.