Using Gem Dependencies if a server is 2.0 instead of 2.1

At work for internal Rails applications, the server is running Rails 2.0.4 and Ruby 1.86. As far as I know, that's not going to change anytime soon and I have no control over it. I was going to try and test this out between a couple of computers and was curious if anyone knew what would happen.

Being the server is on 2.0.4, I'd like to build Rails 2.3.5 applications for that server if at all possible. From what I understand so far, it won't be a problem if I freeze gems and upack dependancies. Does that sound right?

Also, the internal work server has no gems beyond what Rails installs. What I'm wondering is, if I can successfully run a 2.3.5 application on the 2.0.4 server, can I also use extra gems and unpack those to use even though the server doesn't have them? I know that it was version 2.1 that introduced Gem Dependencies so would a 2.3.5 Rails app开发者_JS百科 running on a 2.0.4 server be able to use required gems that are unpacked into an application?

One of the worst things with this situation is even if the above stuff works, the server being on 1.86 would exclude me from using a lot of really cool gems that require Ruby 1.87 (like Formtastic).

Thanks

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You can manually specify the version of Rails being used in the application in the conf/environment.rb file with the RAILS_GEM_VERSION variable.

You won't be able to gems that aren't installed on your server because the application won't be able to find the libraries.

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I went ahead and did the leg work to test this out. If this helps anyone else:

Rails 2.3.5 will run fine on a 2.0.x server. With Rails 2.1 or above, you can unpack gems and your app will work on a 2.0.x server (lower version server). These are the steps I took in order. The only thing unique here is the Rack version is specific to Rails 2.3.5 (and below). In version 2.3.6 and up they switched to rack 1.1. I'm sticking to 2.3.5 because of the Rack issues with 2.3.6 and up, like broken multipart uploads).

• (inside your application directory).
• rake rails:freeze:gems
• rake gems:unpack:dependencies
• (Create a Gems Folder in the vendor folder if it's not there)
• (Navigate inside the gems folder: your_app\vendor\gems)
• gem unpack rack -v="1.0.1"
• (There should now be a folder called "rack-1.0.1" inside the gem folder)
• (Navigate back out to your application root folder)
• rake gems:refresh_specs

I tested this out using the authlogic gem - moving the project over to a spare laptop that only had Rails 2.0.4 installed and no other gems (except MySQL and Mongrel). The only thing I'm not sure about yet is if a gem that requires a script file be run for installation after the gem file (like Simple Forms) will work. I'm going to test that out next when I get time.