providers/docker: nicer error if package is called [GH-4595]

CHANGELOG.md

@@ -4,6 +4,7 @@ BUG FIXES:
 
   - core: Fix cases where sometimes SSH connection would hang.
   - providers/docker: Create args works. [GH-4526]
+  - providers/docker: Nicer error if package is called. [GH-4595]
   - providers/virtualbox: Show a human-friendly error if VirtualBox didn't
       clean up an existing VM. [GH-4681]
   - provisioners/docker: Search for docker binary in multiple places. [GH-4580]

plugins/providers/docker/action.rb

@@ -45,6 +45,12 @@ module VagrantPlugins
         end
       end
 
+      def self.action_package
+        lambda do |env|
+          raise Errors::PackageNotSupported
+        end
+      end
+
       # This action just runs the provisioners on the machine.
       def self.action_provision
         Vagrant::Action::Builder.new.tap do |b|

plugins/providers/docker/errors.rb

@@ -25,6 +25,10 @@ module VagrantPlugins
         error_key(:docker_provider_nfs_without_privileged)
       end
 
+      class PackageNotSupported < DockerError
+        error_key(:package_not_supported)
+      end
+
       class StateNotRunning < DockerError
         error_key(:state_not_running)
       end

templates/locales/providers_docker.yml

@@ -151,6 +151,11 @@ en:
         is functional and properly configured.
 
         Host VM ID: %{id}
+      package_not_supported: |-
+        The "package" command is not supported with the Docker provider.
+        If you'd like to commit or push your Docker container, please SSH
+        into the host VM (if there is one), and run `docker commit` and
+        so on manually.
       state_not_running: |-
         The container never entered the "running" state, or entered it
         briefly but reverted back to another state. Please verify that