Unable to install vagrant-libvirt plugin due to gem conflict: excon-0.109.0 vs excon (~> 1.0)

[pakosaan]

Debug output

Installing the 'vagrant-libvirt' plugin. This can take a few minutes...
/opt/vagrant/embedded/lib/ruby/3.1.0/rubygems/specification.rb:2288:in `raise_if_conflicts': Unable to activate fog-core-2.6.0, because excon-0.109.0 conflicts with excon (~> 1.0) (Gem::ConflictError)
    from /opt/vagrant/embedded/lib/ruby/3.1.0/rubygems/specification.rb:1419:in `activate'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/bundler.rb:769:in `block in activate_solution'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/bundler.rb:766:in `each'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/bundler.rb:766:in `activate_solution'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/bundler.rb:606:in `internal_install'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/bundler.rb:358:in `install'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/plugin/manager.rb:141:in `block in install_plugin'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/plugin/manager.rb:151:in `install_plugin'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/plugins/commands/plugin/action/install_gem.rb:33:in `call'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/action/warden.rb:38:in `call'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/action/builder.rb:183:in `call'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/action/runner.rb:104:in `block in run'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/util/busy.rb:22:in `busy'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/action/runner.rb:104:in `run'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/plugins/commands/plugin/command/base.rb:17:in `action'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/plugins/commands/plugin/command/install.rb:73:in `block in execute'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/plugins/commands/plugin/command/install.rb:72:in `each'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/plugins/commands/plugin/command/install.rb:72:in `execute'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/plugins/commands/plugin/command/root.rb:69:in `execute'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/cli.rb:67:in `execute'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/lib/vagrant/environment.rb:319:in `cli'
    from /opt/vagrant/embedded/gems/gems/vagrant-2.4.1/bin/vagrant:248:in `<main>'

Expected behavior

The plugin to be installed successfully and show it when $ vagrant plugin list

Vagrant version

Vagrant 2.4.1

Host operating system

# System Details Report
---

## Report details
- **Date generated:**                              2024-11-09 10:24:19

## Hardware Information:
- **Hardware Model:**                              Lenovo IdeaPad 3 15ALC6
- **Memory:**                                      8.0 GiB
- **Processor:**                                   AMD Ryzen™ 5 5500U with Radeon™ Graphics × 12
- **Graphics:**                                    AMD Radeon™ Graphics
- **Disk Capacity:**                               500.1 GB

## Software Information:
- **Firmware Version:**                            GLCN63WW
- **OS Name:**                                     Fedora Linux 41 (Workstation Edition)
- **OS Build:**                                    (null)
- **OS Type:**                                     64-bit
- **GNOME Version:**                               47
- **Windowing System:**                            Wayland
- **Kernel Version:**                              Linux 6.11.6-300.fc41.x86_64

Steps to reproduce

1. vagrant plugin install vagrant-libvirt

[pakosaan]

I downgraded to version 2.4.0 and its woriking but hope it is fiexed soon

[trinitronx]

I should add that this issue will affect any OS due to the gem dependency conflict on excon.

What happened here is:

• Upstream dependency fog-core 2.6.0 just bumped the dependency on excon from ~> 0.71 to ~> 1.0
  • vagrant-libvirt depends on fog-core ~> 2 and thus now after fog/fog-core@c6bbad9, sub-dependency constraint: excon ~> 1.0
  • This crosses the typical SemVer MAJOR version constraint boundary for just excon, while maintaining that fog-core just incremented the MINOR version.
  • This is generally fine so long as fog-core's API itself has not experienced breaking changes.
  • In .gemspec, the general rule of thumb "best practice" is to keep the pessimistic version constraint operator on the major version boundary only, assuming that SemVer ensures breaking changes will increment the MAJOR version (again, this is generally fine...)
• Vagrant 2.4.2 installation still includes the embedded version of excon v0.112.0: /opt/vagrant/embedded/gems/gems/excon-0.112.0/
• The new strict version dependency constraint, excon ~> 1.0, triggers here because this embedded version (0.112.0) of the dependency doesn't satisfy the constraint: ~> 1.0.

Therefore, get this error:

Installing the 'vagrant-libvirt' plugin. This can take a few minutes...
/opt/vagrant/embedded/lib/ruby/3.3.0/rubygems/specification.rb:2245:in `raise_if_conflicts': Unable to activate fog-core-2.6.0, because excon-0.112.0 conflicts with excon (~> 1.0)

So, while the plugins and their sub-dependencies are generally following the ideal case for specifying and bumping version constraints... due to Bundler & Ruby requiring sub-dependency gems to satisfy all the constraints, we end up with excon straddling the MAJOR version boundary. Thus, there's now a conflict between Vagrant's sub-dependencies and vagrant-libvirt plugin's sub-dependencies. Unless Bundler & Ruby allowed for isolated trees of leaf sub-dependencies to have different versions across an entire project stack, we need to match the versions being used across the plugin ecosystem.

In other words: Unless Bundler & Ruby adopt a sub-dependency isolation model (e.g. similar to NPM), Vagrant + plugins will need to match compatible version constraints for their dependencies across the ecosystem.

Further details explained here

Suggested Solution

• Vagrant should bump dependency constraint to: excon ~> 1.0
• Test & update where needed in case of breaking changes
• Release a new version accordingly to maintain compatibility with the plugin ecosystem

What inside Vagrant depends on excon?

To figure this out, I installed the bundler-dependencies gem and ran the following:

$ git clone https://github.com/hashicorp/vagrant.git
$ rvm gemset create vagrant
$ rvm use ruby-3.1.2@vagrant
$ bundle install
$ gem install bundler-dependencies

$ bundle dependencies find excon
1 gems depend on excon:

vagrant
  * vagrant → vagrant_cloud → excon

So, the source of the dependency is vagrant_cloud pulling in excon.

EDIT: So, it looks like vagrant_cloud v3.1.2 has been released, now depending on excon ~> 1.0!

Now this just needs to bubble up into a Vagrant release and it should solve this issue! 🎉 👏

[chrisroberts]

Sorry for the delay on this. As noted above, the vagrant_cloud gem was published with updated dependency constraints to loosen them and the 2.4.3 version of Vagrant has been released which will pull in this new version.

Cheers!