How to use Bundler 2.0 on MRI 2.6.0?

[eregon]

I can install the gem with gem install bundler, but it's not used:

$ gem list

*** LOCAL GEMS ***

bigdecimal (default: 1.4.1)
bundler (2.0.1, default: 1.17.3)
...

$ bundle --version
Bundler version 1.17.3

$ bundle _2.0.1_ --version
Traceback (most recent call last):
	2: from /home/eregon/.gem/ruby/2.6.0/bin/bundle:23:in `<main>'
	1: from /home/eregon/.rubies/ruby-2.6.0/lib/ruby/site_ruby/2.6.0/rubygems.rb:302:in `activate_bin_path'
/home/eregon/.rubies/ruby-2.6.0/lib/ruby/site_ruby/2.6.0/rubygems.rb:283:in `find_spec_for_exe': Could not find 'bundler' (1.16.1) required by your /home/eregon/code/mspec/Gemfile.lock. (Gem::GemNotFoundException)
To update to the latest version installed on your system, run `bundle update --bundler`.
To install the missing version, run `gem install bundler:1.16.1`

And running that (or bundle _2.0.1_ update --bundler) doesn't change the Gemfile.lock.

I also tried to update RubyGems with gem update --system, but that doesn't help either.

[deivid-rodriguez]

We definitely need to better communicate this, but it sounds like your lock file is locked to bundler 1.16.1 (BUNDLED WITH 1.16.1). You have 2 options: either upgrade your lock file to the bundler version you are using (bundle update --bundler), or use the bundler version you're locked to (gem install bundler:1.16.1).

[deivid-rodriguez]

The fact that bundle update --bundler does not update your lock file seems like a bug, also reported here. I'm planning to investigate this in the future.

[eregon]

It's quite confusing imho, I would expect bundler to be "a gem" and so when I install version 2.0.1, the latest version is used like for other gems.
Compatibility would then be achieved by having code in Bundler 2.0 that cares about that, rather than relying on a bundler 1.x gem being installed, and having RubyGems or Bundler magically choose a different version based on the Gemfile.lock in the current directory.
This also means releases of 1.x would be less needed, but right now 1.x has to be maintained because 2.x cannot run 1.x Gemfile.lock, right?

[eregon]

This blog post explains the behavior, but I still find it surprising. Running bundle --version in a directory without a Gemfile.lock, I can indeed see Bundler version 2.0.1.

@colby-swandale What's the plan to drop 1.8.7 support, but still support existing Gemfile.lock files which will keep existing for a while?
Should Bundler 2 support these existing Gemfile.lock files, and not support Ruby 1.8.7? That would make sense to me, and then Bundler 1.x could be truly deprecated.

[alexshapalov]

I have the same issue and I changed my ruby version from 2.6.1 to 2.5.3. Only this helped. before that, I tried everything.

[eregon]

@colby-swandale @deivid-rodriguez @hsbt I'd like to have your opinion on this issue, regarding my latest comment. What's the plan to drop 1.8.7 in Bundler 2.x but still support 1.x Gemfiles? Is it hard to support 1.x Gemfiles with Bundler 2? I would expect it's not, and that would allow to really deprecate Bundler 1.x.

[hsbt]

@SashkaSh Try to use Ruby 2.6.2. I fixed some of the issues related to this.

@eregon I'm not sure what your concerns. But Bundler 2 still support 1.x Gemiles and drop to support Ruby 1.8 and 1.9 now.

[deivid-rodriguez]

@eregon I think this is precisely what we are addressing in rubygems/bundler#6996 and #2696. I'm working on both right now.

[eregon]

@hsbt

@eregon I'm not sure what your concerns. But Bundler 2 still support 1.x Gemiles and drop to support Ruby 1.8 and 1.9 now.

AFAIK, RubyGems magically switches to use Bundler 1 in that case. I find that behavior very confusing.

Bundler 2 does not work at all if there is a Gemfile.lock with BUNDLED WITH 1.16.4:

$ chruby 2.6.2
$ gem install bundler
$ bundle version
Bundler version 1.17.2 (2018-12-19 commit 3fc4de72b)
$ bundle _2.0.1_ version
Traceback (most recent call last):
	2: from /home/eregon/.rubies/ruby-2.6.2/bin/bundle:23:in `<main>'
	1: from /home/eregon/.rubies/ruby-2.6.2/lib/ruby/2.6.0/rubygems.rb:302:in `activate_bin_path'
/home/eregon/.rubies/ruby-2.6.2/lib/ruby/2.6.0/rubygems.rb:283:in `find_spec_for_exe': Could not find 'bundler' (1.16.4) required by your /home/eregon/tmp/Gemfile.lock. (Gem::GemNotFoundException)
To update to the latest version installed on your system, run `bundle update --bundler`.
To install the missing version, run `gem install bundler:1.16.4`

[hsbt]

@eregon It's intentional behavior. You need to run bundle update --bundler for using Bundler 2 includes 2.0 and 2.1.

[deivid-rodriguez]

This is related to the ongoing discussion about the version switcher, so I'll close this ticket in favor of those.