I am exploring the world of Ruby and RVM. I am going through a lot of documentation and trying out RVM, but I am a bit confused about the entire work flow. I am writing down the workflow as I understand it. Can someone please take a look and see if this understanding is correct?
I am using a Mac.
RVM is essentially a script that allows us to manage Ruby environments for development purposes.
RVM allows switching between different versions of Ruby with rvm use 1.9.2.
To use a particular gemset with the current Ruby version, we need to create a gemset using
rvm --create gemset rails235
Install the gem using gem install rails -v=2.3.5
Q: What happens if I did gem install rails -v=2.3.5 prior to creating a gemset? Will there be two copies of the same Rails installed under RVM's Ruby 1.9.2?
Q: What happens if I install 2.3.5 and 3.1.0 prior to creating gemsets and then create a gemset for each version?
Q: where does rvmrc come into picture in the whole story?
Any other information that helps me get this straight is extremely helpful.
#Kiran, this is in reference to your comment above. When you install a different version of ruby with rvm, it'll add to this list:
$ rvm list
rvm rubies
=> ruby-1.9.2-p290 [ i386 ]
On my system, I've only got one version running (for now). This helps too
$ rvm gemset list
gemsets for ruby-1.9.2-p290 (found in /Users/mike/.rvm/gems/ruby-1.9.2-p290)
global
=> mg_diaspora
rails3
railscasts
ruby
sorcery
The practice is to install common gems into your global gemset and create/use sets for everything else. I tend to keep pry and others in the global gemset. As Mike K. said, you'd never do #2; if you did do such a thing, I would imagine global having priority.
#3 .rvmrc
You can do things like this in the file:
rvm use 1.9.2#rails3 --create
This will ensure whenever you 'cd' into the directory, it'll switch to 1.9.2 and it's 'rails3' gemset; the following attribute ensures the gemset will be created if it doesn't already exist.
Update
Ex: if I say rvm use 1.9.2#rails3 --create how does this pick the version of rails3.1.0 gem
Because by the time this rails3 gemset is created I already have 2 versions of rails gems?
That's easy - when you run bundle install it creates a Gemfile.lock; this essentially 'locks' the gems that your application is set to use. You've never require two different versions of rails in a single Gemfile anyways - that's just ridiculous =)
1) Rvm automatically creates an #global gemset per interpeter so if you did what you state in the first question you'd have a 2.3.5 in the global gemset.
2) I'm not sure why you would do this.
3) rvmrc is just where you can specify environment info like bashrc, i use it to specify my default architecture for instance. It gets read when rvm gets sourced in your profile.
Basically global is a mix-in for all other gemsets under a specific interpreter. So, if you put rake and say bundler into the global gemset, and then create and enable your own gemset under that specific ruby, it will have both the gems you install in that gemset AND global.
You will see it as a single gemset though. Also, if you attempt to delete a gem that is in global while still in, say, mygemset you will not be able to delete it. This is to protect other gemsets from having gems mixed in from global that they rely on from being removed. You would have to either explicitly change to global or execute something like
rvm 1.9.2-p290#global exec gem uninstall rake -v='0.9.2'
Also, bear in mind that there is a significant difference between 'default' and 'global'. The 'default' gemset is not really a gemset perse. This is selected when you do something like
rvm use 1.9.2
Notice you did not select a gemset in the above command. This is where default lives and plays. When no gemset is selected, default becomes active and global totally disappears. To load default, you would modify $rvm_path/gemsets/default.gems as these are the list of gems to be installed into each interpreter's 'default' set. The other file there is 'global.gems'. This is used as you would surmise; to load a default set of gems whenever you install a new interpreter under RVM into the global gemset, which is shared by all other gemsets for that Ruby, but not for 'default'.
Please see https://rvm.beginrescueend.com/gemsets/basics/ for more information.
Related
I'm having difficulty understanding RVM per project gemsets. I've installed RVM and the 1.9.2 and 1.8.7 rubies, as per http://beginrescueend.com/interpreters/ruby/ , and when I want to start a new project, I've been
cd ~/Code
rvm use 1.9.2
rvm gemset create test1
rvm gemset use test1
gem install rails
But this takes a long time! (installing rails). I then rails new test1; cd test1
I'm really unsure with the correct workflow. If I'm making a new app to test in, I don't want to have to wait for rails to install.
It seems from http://beginrescueend.com/gemsets/basics/ that I can create a rails gemset, but then how do I create a per project gemset?
Edit:
If I'm going to using multiple ruby/rails versions, should I create a gemset, say 1.9.2#rails313, then rails new blah, put 1.9.2#rails313 in blah/.rvmrc , and if I need to later on, create a blah gemset?
A gemset is just a container you can use to keep gems separate from each other.
The Big Idea: creating a gemset per project allows you to change gems (and gem versions) for one project without breaking all your other projects. Each project need only worry about its own gems. This is a Good Idea, and the wait time for installing large gems like Rails is usually worth it.
That said, if you're going to use the same version of Rails across all your projects and want to save time, you can install rails (and maybe rake as well) in the 'global' gemset - these gems are available in all gemsets for that version of ruby.
Assuming you already have a test1 gemset:
$ rvm gemset use global
$ gem install rails
$ gem install rake
$ rvm gemset use test1
$ rails test1
Once I wrote a simple blog post on how to use RVM with gem sets, this might be helpful to you.
UPDATE: As the link above is dead, I believe it is in another location here.
I have several servers for development, staging, testing and production and want to keep my Ruby version and Gem versions in sync between the different machines -- what's the best way to do this?
If you're using Rails 3, you can just use the Gemfile, and bundler, and when you do a "bundle update" on whatever machine you're on, it will automatically install the correct versions of Gems for that user account.
You should use RVM to manage your Ruby versions and to keep the Gems for different Ruby versions separate from each other.
You should also create a "gemset" for your Rails application, to make sure that the Gems installed there are not modified from another Rails application you might use or develop on the same machine.
http://beginrescueend.com/
http://railscasts.com/episodes/200-rails-3-beta-and-rvm
rvm is the best option to manage ruby versions
However I am not sure if you really want to change ruby version often.
bundler & Gemfile is great way to handle gem versions
Track you Gemfile && Gemfile.lock files in git(or other cvs) tree, and run bundle install on change
You can also, in the event you have more gems in a gemset than just what's in your Gemfile, do a
rvm gemset export gemsetname.gems
And then on the other machine you would do a
rvm gemset import gemsetname.gems
You can even do it as
rvm x.x.x#mygemset exec rvm gemset export mygemset.gems
so you don't have to go directly into your gemset. And then on the new machine,
rvm --create use x.x.x#mygemset && rvm gemset import mygemset.gems
which will create and then populate your mygemset gem set.
What are the benefits & drawbacks of installing things into the #global gemset in RVM?
Let's say I want to install different versions of rails on the same server. I then want the ability to install multiple ruby apps on the same server, with the least duplication of files to save on disk space. However, I still want to avoid dependency problems, gem conflict issues and other problems.
Let's also assume that each app has extra gems it needs that I only want in it's local project gemset.
Would I be better off:
Installing both Rails 3 and Rails 2 gems into the #global gemset
...And use project-local gemsets for their gems...
Installing Rails 3 into a #rails3 gemset, and Rails 2 into a #rails2 set... then cloning for each project I need?
For example:
rvm use ree#rails3 && rvm gemset export rails3.gems
rvm use ree#rails2 && rvm gemset export rails2.gems
rvm use --create ree#project1-on-rails3 && rvm gemset import rails3.gems
Install more project-local gems here...
rvm use --create ree#project2-on-rails2 && rvm gemset import rails2.gems
Install more project-local gems here...
Something else entirely...
NOTE: I wrote this whole response assuming that you are using Bundler to manage your gem dependencies. I realize that some people don't, and you didn't mention Bundler in your question. If you aren't using Bundler, I would point out that it probably is the best way to conserve disk space (only if you bundle install --system, though!). If you are using exported gemsets to manage dependencies, I think your scheme sounds reasonable, but I have no experience with it.
Both Rails 3, and Rails 2 with Bundler will set their load path appropriately such that they will not load any gems (or any versions of any gems) that are not in the Gemfile.lock. There's not really any way that I've experienced to have a "gem dependency problem" on the server. It is important that you run bundle install on your development machine whenever you modify the Gemfile, and that you check your Gemfile.lock into source control, as described on the Bundler homepage.
I spent some time digging into the use-cases of gemsets back in January. The reasons I found to use separate gemsets for each project were:
Your shell environment is the same as your application environment (scripts run correctly without bundle exec).
You can easily browse and grep through the source code of all your dependencies, by navigating to the gemset install directory.
It prevents some reported ‘heisenbugs’, according to the author of RVM. I have experienced something like this where a gem executable wasn't available and bundle exec didn't seem to help.
I don't think any of these benefits are very compelling on the server, so if you are aiming to conserve disk space, I'm not sure why you would use gemsets at all.
Actually, the only reason I've used rvm at all on the server was because it was a convenient way to build ruby from source (we needed a version that wasn't available in the native package manager).
I'm confused, what does the #rails3 do when creating a new gemset?
I want to run both rails2.1.1 and rails3 applications, and switch between the two.
I create a rvm for 1.9.2 and 1.8.7
And inside 1.9.2 I created 2 gemsets, and installed rails 2.1.1 in one gemset, and rails3 in another gemset.
Am I doing this right?
I'm reading others use the #rails3 in the gemset creation process, and it helps isolate things?? Can someone explain this as I don't get it.
Should I delete the gemsets and start over? or is it higher up that I have to delete?
There are rubies and gemsets. 1.9.2 and 1.8.7 are your rubies. Each ruby version can have many gemsets (each gemset is tied to one ruby install on your rvm). Personally, I have created a new gemset for each new project to help isolate the gems needed for that project from any other project.
rails is a gem, so it is usually recommended to isolate it and all the gems it depend on into a gemset.
otherwise, you can also use
rails _2.1.1_ -v
to invoke rails 2.1.1, although the usual recommendation is to create separate gemsets. You can see a lot of info of the gems by rvm info, and rvm list gemsets. Each gemset is a separate folder and keep things isolated from each other quite well.
So I want to create environments for rails 3 and rails 2.1.1
How do I do this?
Where do I look for the various versions of rails?
I get an error when I try:
rvm 1.9.2-head
ruby ruby-1.9.2-head is not installed.
I just followed what I read on: http://rvm.beginrescueend.com/gemsets/creating/
Yes, gemsets are ideal for this. I use gemsets for this too.
First you have to create the gemset:
rvm gemset create your-project-name
then use the gemset:
rvm gemset use your-project-name
When you do this, all your gems are unreachable, you can get them back by using rvm gemset use, which will return to the default gemset (unnamed).
Inside your gemset, you will have to reinstall all needed gems. If you are using bundler, it is as simple as
bundle install
The advantage of using gemsets is that your gems are cleanly seperated. For instance, i ran into trouble with spec/rspec scripts when using both rails2 and rails3 together. With gemsets i no longer have any problems. Using an .rvmrc file per project, even the selection of the correct gemset is automatic, and i can configure my project in rubymine to use the correct gemset too. Awesome :)
Rvm is for different versions of Ruby not rails. You can potentially have every version of rails installed on one version of ruby. The application itself will in it's Gemfile or config specify what version of rails you are using.