Only load the dependencies needed for the serve command if the serve command is being run. This allows Vagrant to properly load on platforms where some of the dependency libraries may not be available due to incompatibilities or being EOL.
Vagrant Core Plugins
These are plugins that ship with Vagrant. Vagrant core uses its own plugin system to power a lot of the core pieces that ship with Vagrant. Each plugin will have its own README which explains its specific role.
Generate proto
grpc_tools_ruby_protoc -I . --ruby_out=gen/plugin --grpc_out=gen/plugin ./plugin_server.proto