Move plugin check into Alpine guest plugin

plugins/guests/alpine/plugin.rb

@@ -45,6 +45,22 @@ module VagrantPlugins
         require_relative 'cap/smb'
         Cap::SMB
       end
+
+      def self.check_community_plugin
+        plugins = Vagrant::Plugin::Manager.instance.installed_plugins
+        if plugins.keys.include?("vagrant-alpine")
+          $stderr.puts <<-EOF
+WARNING: Vagrant has detected the `vagrant-alpine` plugin. This plugin's
+functionality has been merged into the main Vagrant project and should be
+considered deprecated. To uninstall the plugin, run the command shown below:
+
+  vagrant plugin uninstall vagrant-alpine
+
+EOF
+        end
+      end
+
+      self.check_community_plugin
     end
   end
 end

plugins/kernel_v2/plugin.rb

@@ -63,19 +63,6 @@ To disable this warning, set the environment variable `VAGRANT_USE_VAGRANT_TRIGG
 EOF
         end
       end
-      if plugins.keys.include?("vagrant-alpine") &&
-        !ENV["VAGRANT_USE_VAGRANT_ALPINE"]
-      $stderr.puts <<-EOF
-WARNING: Vagrant has detected the `vagrant-alpine` plugin. This plugin conflicts
-with the internal Alpine Linux guest plugin. Please uninstall the
-`vagrant-alpine` plugin and run the command again if you wish to use the core
-Alpine Linux guest plugin. To uninstall the plugin, run the command shown below:
-
-vagrant plugin uninstall vagrant-alpine
-
-To disable this warning, set the environment variable `VAGRANT_USE_VAGRANT_ALPINE`.
-EOF
-      end
     end
   end
 end

test/unit/plugins/guests/alpine/plugin_test.rb

@@ -0,0 +1,32 @@
+require File.expand_path("../../../../base", __FILE__)
+
+
+describe VagrantPlugins::GuestAlpine::Plugin do
+  let(:manager) { double("manager") }
+
+  before do
+    allow(Vagrant::Plugin::Manager).to receive(:instance).and_return(manager)
+  end
+
+  context "when vagrant-alpine plugin is not installed" do
+    before do
+      allow(manager).to receive(:installed_plugins).and_return({})
+    end
+
+    it "should not display a warning" do
+      expect($stderr).to_not receive(:puts)
+      VagrantPlugins::GuestAlpine::Plugin.check_community_plugin
+    end
+  end
+
+  context "when vagrant-alpine plugin is installed" do
+    before do
+      allow(manager).to receive(:installed_plugins).and_return({ "vagrant-alpine" => {} })
+    end
+
+    it "should display a warning" do
+      expect($stderr).to receive(:puts).with(/vagrant plugin uninstall vagrant-alpine/)
+      VagrantPlugins::GuestAlpine::Plugin.check_community_plugin
+    end
+  end
+end

test/unit/plugins/kernel_v2/plugin_test.rb

@@ -1,20 +0,0 @@
-require File.expand_path("../../../base", __FILE__)
-
-
-describe VagrantPlugins::Kernel_V2::Plugin do
-  before do
-    expect($stderr).to receive(:puts)
-  end
-
-  it "should display a warning if vagrant-alpine plugin is installed" do
-  end
-
-  context "when VAGRANT_USE_VAGRANT_ALPINE=1" do
-    before do
-      ENV["VAGRANT_USE_VAGRANT_ALPINE"] = "1"
-    end
-
-    it "should not display a warning" do
-    end
-  end
-end

website/source/docs/other/environmental-variables.html.md

@@ -296,11 +296,6 @@ jailbreak by setting `VAGRANT_SKIP_SUBPROCESS_JAILBREAK`.
 
 Vagrant will append the contents of this variable to the default user agent header.
 
-## `VAGRANT_USE_VAGRANT_ALPINE`
-
-Vagrant will not display the warning about disabling the core Alpine Linux guest
-plugin if the community plugin is installed.
-
 ## `VAGRANT_USE_VAGRANT_TRIGGERS`
 
 Vagrant will not display the warning about disabling the core trigger feature if