Port-forwarding with SSH ProxyCommand fails with "exec ssh ... not found"

[stygian-coffee]

Describe the bug

If using a Libvirt daemon on a remote host and attempting to forward ports, port forwarding fails.

I think that this is related to

vagrant-libvirt/lib/vagrant-libvirt/action/forward_ports.rb

Line 113 in a94ce0d

options += ['-o', "ProxyCommand=\"#{ssh_info[:proxy_command]}\""] if machine.provider_config.proxy_command && !machine.provider_config.proxy_command.empty?

Namely, I think that "ProxyCommand=\"#{ssh_info[:proxy_command]}\"" should be changed to "ProxyCommand=#{ssh_info[:proxy_command]}"

I think that this bug was introduced in 55a220f.

To Reproduce

Set up an SSH server so that you can SSH to localhost.

Use the following Vagrantfile:

Vagrant.configure("2") do |config|
  config.vagrant.plugins = "vagrant-libvirt"

  config.vm.box = "generic/ubuntu2204"

  config.vm.hostname = "test"
  config.vm.network("forwarded_port", guest: 8080, host: 8080)
  config.vm.provider("libvirt") do |lv|
    lv.host = "localhost"
    lv.connect_via_ssh = true
  end
end

Run vagrant up. Notice that port 8080 is not forwarded. Read the log in .vagrant/machines/default/libvirt/logs/ssh-forwarding-\*_8080-192.168.121.250_8080.log. It will say something similar to:

zsh:1: command not found: ssh 'localhost' -W 192.168.121.250:22
kex_exchange_identification: Connection closed by remote host
Connection closed by UNKNOWN port 65535

Expected behavior
Port 8080 is forwarded.

Versions (please complete the following information)::

• Libvirt version: 8.0.0
• Vagrant version: 2.3.7
• Vagrant flavour: upstream (NixOS)
• Vagrant plugins versions (including vagrant-libvirt): vagrant-libvirt (0.12.2, system)

Debug Log
Attach Output of VAGRANT_LOG=debug vagrant ... --provider=libvirt >vagrant.log 2>&1
vagrant.log

[stygian-coffee]

For anyone else who runs into this issue, I was able to find this workaround:

Vagrant.configure("2") do |config|
  config.vagrant.plugins = "vagrant-libvirt"

  config.vm.box = "generic/ubuntu2204"

  config.vm.hostname = "test"
  config.vm.network("forwarded_port", guest: 8080, host: 8080)
  config.vm.provider("libvirt") do |lv|
    lv.host = "localhost"
    lv.connect_via_ssh = true

    tmpdir = Dir.mktmpdir()
    ENV["PATH"] += ":#{tmpdir}"
    ["\"", "\\\"", "\" "].each do |filename|
      File.open("#{tmpdir}/#{filename}", "w") do |f|
        f.write(<<-EOF
          #!/bin/sh
          exec $@
        EOF
        )
      end
      FileUtils.chmod("+x", "#{tmpdir}/#{filename}")
    end
    lv.proxy_command = "\\\" \" ssh localhost -W %h:%p #\""
  end
end

Unfortunately, this only works for non-privileged ports since vagrant-libvirt invokes sudo for privileged ports, and sudo strips the PATH variable.