My question is very similar to How do I freeze gems into a Rails 3 application?, but I only want to freeze a single modified gem. The answers to that question seem to result in bundling all the application's gems.
In case it's relevant, I need to do this so the modified gem gets installed on Heroku.
I checked the bundle-install doc but it didn't seem to address this situation. I can't imagine it's that uncommon, though. Any guidance is appreciated.
Well, Bundler is going to freeze all of them, and the idea is that you want to freeze not only a single gem, but the collection of gems that produced a working copy of your app.
That being said, on your local dev machine, you can do bundle update [name of gem] and it will update just that one gem to the latest version within the restrictions specified in your Gemfile, which also updates your Gemfile.lock, which effectively updates just that one gem on Heroku when you next deploy.
If you're using bundler, which is the default for Rails 3, you can always fork the gem to your own git repository and add that definition to your Gemfile with whatever location it can be found at:
gem 'thegem', :git => 'git://github.com/cloned_to_me/thegem.git'
Another option is to use bundle package to save copies of the gems in vendor/cache. These can then be later installed using bundle install --local according to the documentation.
This is the closest thing to the Rails 2 "freeze" method, but has the added advantage of saving the gems before they are installed, not after, avoiding any platform-specific problems as was the case previously.
With thanks to those who answered the question with related approaches, I ended up going with the approach mentioned in this sister question. For the sake of clarity, this is what I did:
Repackage modified gem as its own gem. This takes a little finagling but is described well in the RubyGems Guides. Move said gem into your source directory (I used vendor/gems)
In the project's Gemfile, point to the location of the new gem:
gem "modified_gem", :path => "vendor/gems/modified_gem"
Add new gem to version control, make sure bundle install isn't messed up with funky settings (e.g. --local), and cross your fingers.
Someone also mentioned that it's possible to mix in changes to the gem instead of overriding source files. I don't know anything more about this technique except that it should be possible.
Related
I'm looking for simple, but good way to cleanup gemfile and make rails startup faster.
How can I get a list of all required gems vs all loaded gems.
bundle clean --force will remove old gems (or older versions of currently-used gems) previously installed, but not currently being used in your current Gemfile.lock manifest.
First, if you want to check what are the gems used by your project, I invite you to run gem server in your project folder root, then go to http://0.0.0.0:8808/
You will be able to understand the dependencies of all the gems your project is using. It will also show you all versions of the same gem.
To remove old versions of gems you can run as #changingrainbows mention
bundle clean --force
After this step run your gem server again and watch the result, a clean and understandable gem list with all dependencies.
It depends what you're after here.
If you're looking to remove old, unused gem versions, then bundle clean.
If you've been adding gems as you develop and have lost track of the ones you actually use, and have good test coverage, then try this answer.
If you want to reduce the number of gems rails pulls in at startup to the bare minimum, try gem_bench.
I think it is impossible. When your APP starts it loads gems from Gemfile.lock but it does not know if they (gems) are needed in your code or not. The APP inform you by raising an exception When something calls a class or method that is undefined if some needed gem is missed (if you remove it from Gemfile), but this can happen at any moment (not during starting your APP).
So if you are looking the way to clean up your gem list I think the best way to do it manually (I know it is not easy way). Analyse each gem to find out what functionality it provides and decide (or find in your code) if it is needed or not. Additionally tests (if you have them) should help you a lot.
What is the use of Gemfile in rails?
How to use Gemfile?
During your development in Rails, there will be times where you will want to provide some functionality which is required by you, but either you don't know how to do or you don't want to implement it on your own since a lot of work has been put into its development by talented developers.
These developments which you might need (user authentication, message system, asset handlers, geolocation, pagination system, linking to exterior services such as Amazon AWS, and last but not least Rails itself) are called Ruby Gems. These are ruby software packages, not necessarily relating to Rails, but since Rails is based on Ruby, 98% of the gems can be made availble to your Rails webapp code.
Lots of gems can be found in github, but its funner to search for gems via ruby-gems or ruby-toolbox
Your gemfile is a list of all gems that you want to include in the project.
It is used with bundler (also a gem) to install, update, remove and otherwise manage your used gems.
The gemfile has another purpose - you can group gems in :development, :test, :assets, :production, etc groups and Rails will know when to include the gems. For example:
group :development, :test do
gem "rspec-rails"
gem "factory_girl_rails"
gem "guard-rspec"
end
Note that on Rails 4, the assets group has been deprecated
These gems belong to development environment and the test environment since they are for testing the application. You don't need them available in the production environment (you could, but that will bloat the memory unnecessarily).
So - To use the gemfile, simply write the gem you wish to install such as
gem 'devise'
make sure to install bundler beforehand (in your console/cmd/ssh) with
$ gem install bundler
and then write in the console
bundle install
you will notice another gemfile appears! Gemfile.lock
This file, as you will see if you open it with a text reader, lists all your gems with their version and their dependencies. This will come useful when you need to know which versions of the gems you installed.
For more reading on the Gemfile - read on the bundler page
for information regarding picking a gem you could start with this
Good luck and have fun!
Ok, so whats this Gemfile.lock that got created?
Gemfile.lock, as the name suggests is a locking on all the versions of all the gems that got installed. So if Gemfile is what required to be installed, the lock file is what got installed and what version are actually required to get the app up and running.
If you don't have the gems in that specific version (as specified in Gemfile.lock) rails will complain and you will have to either install the missing gems (via bundle install) or fix any conflicts manually (I believe bundler will give you some clues on that)
Some things to know about Gemfile.lock
if you accidently delete it, it will get regenerated when you run bundle install. If you accidently delete Gemfile, you are out of luck.. You should use git :)
Heroku doesn't care about Gemfile.lock since it will reinstall all gems. So for Heroku, you must set the gem version you want, or Heroku will always install the latest version of gem, which may cause issues
Keep the Gemfile.lock in your project so you will always know what version of gems make your app work properly.
Gemfiles are configuration for Bundler, which is used to manage your application's Ruby dependencies. That website includes a lot of documentation, including the Gemfile manual page.
Explanation by analogy
You want to build a car. From scratch. You need to build: a chasis, engine, corroborator, radiator etc.
Gems allow you to utilise car parts which other people have made before
Everyone's who's ever built a car has needed the same things.
You needn't reinvent the wheel. Why make your own engine etc when you can get it straight off the shelf? What if you could get one of the best engines around, created by the most talented engineers in the world, without lifting a finger? Are you gonna spend a year trying to make your own?
So basically rather than make everything yourself, you write down a shopping list of all the parts you need:
Rolls Royce Engine
AutoLive seatbelts
Michellin tyres.
PIAA Night headlights
etc etc.
That my friend, is basically your gem file!
Your system can have lots of gems ... thus can have multiple versions of same gem.
A Gemfile specifies the list of gems with their versions that shall be used/loaded/(install if not present) whenever you run your rails application. or anything with bundle exec . .
Firstly, what is a gem?
According to Wikipedia:
RubyGems is a package manager for the Ruby programming language that
provides a standard format for distributing Ruby programs and
libraries
Gemfile
A Gemfile is a file we create which is used for describing gem
dependencies for Ruby programs
Now, in very very simple words:
Gem can be thought of as a library which you can use in your code.
Example: faker gem
Your code can use the functionality of faker gem to produce fake data.
Now you can list all the gems that your project requires in the gemfile.
When you do a bundle install, all the gems in your gemfile are installed for you.
I am developing a Rails app that uses a gem that I am also developing.
Every change that I make in the gem I have to: build, uninstall previously installed gem, install built gem, restart rails app.
You can imagine that it easily becomes a nightmare to make even litle changes in the gem.
I´ve tried to manually load all files that are configured to be loaded by the gem (at Gemspec) but it always seem to be some problem in the loading process, not finding libraries or not loading in the proper order.
Is there a way to set my environment to better develop my gem with my app?
You can just add a file reference to your local filesystem in your Gemfile, like
gem 'new_gem', :path => '~/RubyPlayground/DevGems/new_gem/'
That way you just need a new bundle install after modifying your new gem.
Update
Reading your description again you might not be using rails 32. My suggestion is of course based on bundler at least.
You could always symlink your gem code to lib/ and then include that in your autoreload paths (application.rb IIRC).
I like to vendor as many gems as possible, except those that must be built on each platform (libxml, etc.) but sometimes I like to use some bleeding-edge code rather than the gems that are out there on the gem servers.
Can I clone a github gem directly into vendor/gems. I guess I could, but will it affect my app code since it is already a git repository? I would like to just do periodic git pulls for these couple of gems so that I don't have to update every gem and maybe break something.
Use of vendor/gems has been deprecated in favor of using Bundler and Gemfile instead. The vendor system had a number of flaws including a lack of support for compiled extensions, so it was never a complete solution.
You're better off locking your versions in the Gemfile as required. If you want to use bleeding edge versions, comment out the version declaration, remove Gemfile.lock and do a bundle install again.
It's often the case that the published version of the gem has a flaw you need to repair by forking and fixing, so it's easy to track this:
gem 'broken-gem', :git => 'git://github.com/myname/broken-gem.git'
The advantage here is that the Gemfile serves as documentation of what versions of the gems you require, and where to get them. vendor/gems leaves people in the dark as to where that version came from.
Using Rails 3, I'm trying to figure out what I think should be pretty straightforward...
I have 2 gems that require 2 different versions of the same gem dependency. Both versions of the dependent gem are installed on my system but I still get an error from Rails: "Bundler could not find compatible versions for gem XXX".
What is the best practice to handle a scenario like this?
I'd go for what #BaroqueBobcat suggests. I just want to add that - if you need the latest Twitter gem and can't wait for the maintainer of Groupon2 to update his gem - you can fork the Groupon2 on GitHub, update its gemspec, see if it still works by running its tests (and try to fix it if it doesn't) and include your own version using its Git URL in your Gemfile like so: gem "groupon2", :git => "https://github.com/yourgithubuser/groupon2.git".
If you want to be nice you can offer your changes to the maintainer of Groupon2 with a pull request for bonus points :)
If you don't need all the features of the Twitter gem version 1.4.1, you could use version 1.2.0, which needs faraday ~> 0.5.4. and that should work. If that doesn't, you could try
poking the owner of groupon2 to update his gem--it's on github https://github.com/gangster/groupon2
.
I was having the same issue, but in a different context: Writing an app which uses two different versions of the hashie dependency (1.2.0 and 3.1.0)
I went into the Gemfile.lock and specified the older version in parentheses hashie (1.2.0), ran bundle install, and it worked.
If you're in a situation where the gems are being used in different projects or at least not at the exact same time you can use RVM's gemset feature as a workaround. I recently had a gem incompatibility similar to yours and that's what I used.
If you have RVM installed, do this:
rvm gemset create gemset_name_here
rvm gemset use gemset_name_here
So what you're doing is creating a gem environment that's totally fresh and from scratch while still being able to revert back to the gems you were working with before at any time. The first line creates a new gemset and the second line tells RVM to start using it.
At this point you'll need to run bundle install or rake or whatever you're using to get the gems you need but this should take care of the problem.
So when you're using gem 1 with dependency 1 you use the gemset that has the required version. Then when you're using gem 2 with dependency 2 you switch to the gemset that has that.
Now, if both gems are part of one larger project this will not be feasible and you'll most likely need to edit the source to of the gem to run the new version of the dependency like #BaroqueBobcat said. In a lot of cases this is actually pretty easy. Ruby developers tend to be very awesome about making their code easy to pick up on.
Take a look at this solution, maybe it will help you: gems
bundle update resolve conflicts