commands/box/remove: if box is in use, warn user, ask for confirmation

lib/vagrant/action/builtin/box_remove.rb

@@ -71,6 +71,49 @@ module Vagrant
           box = env[:box_collection].find(
             box_name, box_provider, box_version)
 
+          # Verify that this box is not in use by an active machine,
+          # otherwise warn the user.
+          users = []
+          env[:machine_index].each do |entry|
+            box_data = entry.extra_data["box"]
+            next if !box_data
+
+            # If all the data matches AND the entry is a seemingly
+            # valid entry, then track it.
+            if box_data["name"] == box.name &&
+              box_data["provider"] == box.provider.to_s &&
+              box_data["version"] == box.version.to_s &&
+              entry.valid?(env[:home_path])
+              users << entry
+            end
+          end
+
+          if !users.empty?
+            # Build up the output to show the user.
+            users = users.map do |entry|
+              "#{entry.name} (ID: #{entry.id})"
+            end.join("\n")
+
+            force_key = :force_confirm_box_remove
+            message   = I18n.t(
+              "vagrant.commands.box.remove_in_use_query",
+              name: box.name,
+              provider: box.provider,
+              version: box.version,
+              users: users) + " "
+
+            # Ask the user if we should do this
+            stack = Builder.new.tap do |b|
+              b.use Confirm, message, force_key
+            end
+
+            result = env[:action_runner].run(stack, env)
+            if !result[:result]
+              # They said "no", so just return
+              return @app.call(env)
+            end
+          end
+
           env[:ui].info(I18n.t("vagrant.commands.box.removing",
                               :name => box.name,
                               :provider => box.provider,

templates/locales/en.yml

@@ -1251,6 +1251,15 @@ en:
         vm_not_running: "VM is not currently running. Please, first bring it up with `vagrant up` then run this command."
       box:
         no_installed_boxes: "There are no installed boxes! Use `vagrant box add` to add some."
+        remove_in_use_query: |-
+          Box '%{name}' (v%{version}) with provider '%{provider}' appears
+          to still be in use by at least one Vagrant environment. Removing
+          the box could corrupt the environment. We recommend destroying
+          these environments first:
+
+          %{users}
+
+          Are you sure you want to remove this box? [y/N]
         removing: |-
           Removing box '%{name}' (v%{version}) with provider '%{provider}'...
       destroy:

test/unit/vagrant/action/builtin/box_remove_test.rb

@@ -6,12 +6,16 @@ describe Vagrant::Action::Builtin::BoxRemove do
   let(:app) { lambda { |env| } }
   let(:env) { {
     box_collection: box_collection,
+    home_path: home_path,
+    machine_index: machine_index,
     ui: Vagrant::UI::Silent.new,
   } }
 
   subject { described_class.new(app, env) }
 
   let(:box_collection) { double("box_collection") }
+  let(:home_path) { "foo" }
+  let(:machine_index) { [] }
   let(:iso_env) { isolated_environment }
 
   let(:box) do
@@ -74,6 +78,71 @@ describe Vagrant::Action::Builtin::BoxRemove do
     expect(env[:box_removed]).to equal(box)
   end
 
+  context "checking if a box is in use" do
+    def new_entry(name, provider, version, valid=true)
+      Vagrant::MachineIndex::Entry.new.tap do |entry|
+        entry.extra_data["box"] = {
+          "name" => "foo",
+          "provider" => "virtualbox",
+          "version" => "1.0",
+        }
+
+        entry.stub(valid?: valid)
+      end
+    end
+
+    let(:action_runner) { double("action_runner") }
+
+    before do
+      env[:action_runner] = action_runner
+
+      box_collection.stub(
+        all: [
+          ["foo", "1.0", :virtualbox],
+          ["foo", "1.1", :virtualbox],
+        ])
+
+      env[:box_name] = "foo"
+      env[:box_version] = "1.0"
+    end
+
+    it "does delete if the box is not in use" do
+      expect(box_collection).to receive(:find).with(
+        "foo", :virtualbox, "1.0").and_return(box)
+      expect(box).to receive(:destroy!).once
+
+      subject.call(env)
+    end
+
+    it "does delete if the box is in use and user confirms" do
+      machine_index << new_entry("foo", "virtualbox", "1.0")
+
+      result = { result: true }
+      expect(action_runner).to receive(:run).
+        with(anything, env).and_return(result)
+
+      expect(box_collection).to receive(:find).with(
+        "foo", :virtualbox, "1.0").and_return(box)
+      expect(box).to receive(:destroy!).once
+
+      subject.call(env)
+    end
+
+    it "doesn't delete if the box is in use" do
+      machine_index << new_entry("foo", "virtualbox", "1.0")
+
+      result = { result: false }
+      expect(action_runner).to receive(:run).
+        with(anything, env).and_return(result)
+
+      expect(box_collection).to receive(:find).with(
+        "foo", :virtualbox, "1.0").and_return(box)
+      expect(box).to receive(:destroy!).never
+
+      subject.call(env)
+    end
+  end
+
   it "errors if the box doesn't exist" do
     box_collection.stub(all: [])