The problem

Calling bundle update GEMNAME will update a lot more gems than you think. E.g. when you do this:

bundle update cucumber-rails

... you might think this will only update cucumber-rails. But it actually updates cucumber-rails and all of its dependencies. This will explode in your face when one of these dependencies release a new version with breaking API changes. Which is all the time.

In the example above updating cucumber-rails will give you Capybara 2.0 (because capybara is a dependency of `cucumber-rail...

To keep JavaScript sources small, it can sometimes make sense to split your webpack bundles. For example, if your website uses some large JavaScript library – say TinyMCE – which is only required on some selected pages, it makes sense to only load that library when necessary.

In modern webpack this is easily doable by using the asynchronous import function.

Say we have an unpoly compiler that sets up TinyMCE like this (code is somewhat simplified):

// TinyMCE as part of the main bundle!

import tinymce from 'tinymce/tinymce'

// U...

Bundler

bundle outdated [--filter-major|--filter-minor|--filter-patch]

Example output for bundle outdated --filter-major

Other examples

A useful flag is --strict as it will only list versions that are allowed by your Gemfile requirements (e.g. does not show rails update to 6 if your Gemfile has the line gem 'rails', '~>5.2').

I also experienced that doing upgrades per group (test, development) are easier to do. Thus --groups might also be helpful.

$ bundle...

1. Install the latest bundler version:

   gem install bundler
   Fetching bundler-2.3.5.gem
   Successfully installed bundler-2.3.5
   1 gem installed
   

2. Update the bundler version in Gemfile.lock:

   bundle update --bundler  
   

3. Confirm it worked:

   $ tail -n2 Gemfile.lock 
   BUNDLED WITH
     2.3.5
   

Notes:

• Bundler should automatically detect the latest installed version. If it does not, you can specify your preferred version like so:

  b...
  

Bundler so far ignored the version specified under BUNDLED_WITH in the Gemfile.lock. This had two annoying consequences:

• If the bundler version on your system was lower than in the Gemfile.lock, you got an error message and had to manually install the correct version.
• If the bundler version on your system was higher than in the Gemfile.lock, bundler silently updated the version in the Gemfile.lock to your system's bundler version. To avoid this, you had to always specify, which version you want to use for each bundler c...

Detect if a gem has been activated

A gem is activated if it is either in the current bundle (Gemfile.lock), or if you have manually activated it using Kernel#gem (old-school).

To detect if e.g. activerecord has been activated:

if Gem.loaded_specs.has_key?('activerecord')
  # ActiveRecord was activated
end

Detect if a particular gem version has been activated

To detect if e.g. activerecord ma...

You can run bundle install in parallel. This might be helpful for development, where you often install many new gems when switching between projects.

1. Find out the number of processors you have:

lscpu

2. Set the config in your ~/.bundle/config globally (replace 8 with your number of proccessors):

bundle config jobs 8

Note

If you suspect parallel execution for bundling issues, you can try serially with bundle install --jobs 1.

Some rubygems come in platform-specific versions (i.e. "x86_64-linux") in addition to the usual "ruby" platform. This is often is done for gems with native extensions that want to deliver precompiled binaries for ease of installation. However, there is an issue on some versions of Bundler (at least 2.3.x) that makes it inconsistent which versions of a gem will be installed.

Why this happens

On (very) old versions of Bundler, the Gemfile.lock could never indicate which version of a gem was installed, i.e. the Gemfile read `nokogiri (1....

A recent patch level Ruby update caused troubles to some of us as applications started to complain about incompatible gem versions. I'll try to explain how the faulty state most likely is achieved and how to fix it.

Theory

When you deploy a new Ruby version with capistrano-opscomplete, it will take care of a few things:

• The new Ruby version is installed
• The Bundler version stated in the Gemfil...

Bundler allows you to specify the name of the Gemfile you want to bundle with the BUNDLE_GEMFILE environment variable.

BUNDLE_GEMFILE=Gemfile.rails.7.2 bundle

By default, bundler will look for a file called Gemfile in your project, but there may be cases where you want to have multiple Gemfiles in your project, which cannot all be named Gemfile. Let's say for example, you maintain a gem and want to run automated tests against multiple rails versions. When you need to bundle one of your secondary Gemfiles, the solution above ...

Calling bundle update (without arguments) updates all your gems at once. Given that many gems don't care about stable APIs, this might break your application in a million ways.

To stay sane, update your gems using the applicable way below:

Projects in active development

Update the entire bundle regularily (e.g. once a week). This ensures that your libraries are up-to-date while it's easy to spot major version bumps which may break the app.

Projects that have not been updated in a while

1. [Update a single gem conservatively](htt...

Capistrano is by default configured to exclude the gems of the groups development and test when deploying to the stages production and staging. Whenever you create custom groups in your Gemfile, make sure to exclude these, if they should not be deployed to the servers. The gems of these groups might not be loaded by rails, however, the deployment process will take longer as the gems will be downloaded and installed to the server.

e.g. to exclude the groups cucumber and deploy, add the following to `config/deploy/production.rb...

Installing gems on a server that has no access to the internet (especially rubygems.org) requires to bundle the gems into the repository itself. This requires to adjust the bundle config in the repository.

1. Execute the following commands to configure bundler:

bundle config set --local path vendor
bundle config set --local disable_shared_gems true

Note

For Bundler < 2 you have to omit the "set": bundle config --local name value.
See here: [https://bundler.io/v1.17/man/bundle-config.1.html](https://bundler.io/v1.17/man...

On application servers, gems are usually bundled into the project directory, at a location shared across deployments.

This is usually shared/bundle inside your project's root directory, e.g. /var/www/your-project/shared/bundle/.
If you can't find that, take a look at current/.bundle/config and look for BUNDLE_PATH.

When you are changing the version of RubyGems or Bundler on a system where gems are installed this way, you must wipe that bundle directory in addition to the user and system gems or gems that are already ins...

Similar to the Webpack Bundle Analyzer, Chrome's new Lighthouse feature …

… shows a visualisation of your JavaScript bundles. It's compatible with sourcemaps and is great for understanding large JavaScript modules used by your page. It can also visualise unused bytes.

This is very helpful to visualize Javascript files in development. It also works on production code, where its usefulness depends on the structure of the productive Javascr...

Using Ruby 1.8.7 you will not be able to use the maximum versions Rubygems 1.8.30 and Bundler 1.17.3 with https://rubygems.org/ anymore. This is a result of a server certificate on December 5th, 2020. The resulting errors will look like following:

• TypeError: can't modify frozen object
• Could not verify the SSL certificate for https://rubygems.org/*
• Bundler::Fetcher::CertificateFailureError: Could not verify the SSL certificate for https://index.rubygems.org/versions.
• `Error fetching data: hostname was not m...

Since May 2011 we are cutting new gems using Bundler, which is less painful than cutting gems using Jeweler. You know a gem was cut using Bundler if you see the word Bundler in a gem project's Rakefile.

This is how to update a gem that was cut using Bundler:

• Say git pull or check out a repository from Github like git clone git@github.com:makandra/geordi.git
• Update the gem version in `lib/project...

Rubygems supports a 2FA for your account. Once enabled you need to provide your personal OTP code for every release. Despite the CLI of the rake release task does not work well with the command prompt for your OTP code with Bundler versions < 2.0.2. It just looks like the task is frozen:

• Workaround 1: Just type your OTP code and hit enter, your gem is released afterwards.
• Workaround 2: Upgrade to Bundler >= 2.0.2.. Your supported Ruby versions for this gem must be >= 2.3.

When r...

tl;dr: Ruby's Bundler environment is passed on to system calls, which may not be what you may want as it changes gem and binary lookup. Use Bundler.with_original_env to restore the environment's state before Bundler was launched. Do this whenever you want to execute shell commands inside other bundles.

Example outline

Consider this setup:

my_project/Gemfile     # says: gem 'rails', '~> 3.0.0'
my_project/foo/Gemfile # says: gem 'rails', '~> 3.2.0'

And, just to confirm this, these are the installed Rails versions for each ...

Call with the server's hostname (and user if you have no SSH agent), e.g.

install-gems-remotely my.server.com
# or without agent:
install-gems-remotely me@my.server.com

When you call it from a rails directory, it uploads your Gemfile, Gemfile.lock as well as the gemspecs of all vendored gems in to a temporary folder on the server and does a bundle install there.

If you need to install gems from anothere Gemfile, just do it like this:
BUNDLE_GEMFILE=Gemfile.something; install-gems-remotely my.server.com

This scri...

I had this error:

> gem install bundler
Successfully installed bundler-2.0.1
1 gem installed

> bundle install
Traceback (most recent call last):
	2: from /home/henning/.rbenv/versions/2.5.1/bin/bundle:23:in `<main>'
	1: from /home/henning/.rbenv/versions/2.5.1/lib/ruby/2.5.0/rubygems.rb:308:in `activate_bin_path'
/home/henning/.rbenv/versions/2.5.1/lib/ruby/2.5.0/rubygems.rb:289:in `find_spec_for_exe': can't find gem bundler (>= 0.a) with executable bundle (Gem::GemNotFoundException)

The cause was that Bundler 2 requires RubyG...

Update RubyGems and Passenger

Bundler requires Rubygems >= 1.3.6. Run gem update --system if you have an older version.
It also is not compatible with older versions of passenger, so bring that up to date as well (2.2.15 works).

If you installed RubyGems through apt (which you should never do!), you may see a message giving you a hint to use apt to update.
Some people advise to install the 'rubygems-update-1.3.7' gem on Ubuntu systems if you used apt to install RubyGems.
I did that - and lost all...

So you're getting this failure when running bundle install on an older project:

Your Gemfile.lock is corrupt. The following gems are missing from the DEPENDENCIES section: 'archive-tar-minitar' 'hoe' 'rcov'

This happens when you are using a new version of Bundler with a project that was bundled with a very old version of Bundler. For reasons unknown, the Bundler dependency API returns different dependencies for some gems (like ruby-debug or rainpress) than the dependencies found in the downloaded gemspecs. While old versi...

When you need to patch an existing gem, one way is to "vendor" the gem by copying it into the vendor/gems directory of your Rails project. You can then make any changes you require and Rails will use the vendored version of the gem after a server restart. Unfortunately you need to perform some additional steps to marry Rails and the copied gem. This notes describes what to do.

With Bundler

This is super-painful. If you just copy the gem to vendor/gems, Rails will complain:

Unpacked gem foolib in vendor/gems has no s...