core: network issues don't halt Vagrant during box update check [GH-3391]

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 BUG FIXES:
 
+  - core: Don't error if network problems cause box update check to
+      fail [GH-3391]
   - guests/fedora: Fix hostname setting. [GH-3382]
   - guests/fedora: Support predictable network interface names for
       public/private networks. [GH-3207]

lib/vagrant/action/builtin/box_check_outdated.rb

@@ -41,6 +41,10 @@ module Vagrant
           update = nil
           begin
             update = box.has_update?(constraints)
+          rescue Errors::BoxMetadataDownloadError => e
+            env[:ui].warn(I18n.t(
+              "vagrant.box_outdated_metadata_download_error",
+              message: e.extra_data[:message]))
           rescue Errors::VagrantError => e
             raise if !env[:box_outdated_ignore_errors]
             env[:ui].detail(I18n.t(

templates/locales/en.yml

@@ -37,6 +37,16 @@ en:
       installed, but your Vagrant machine is running against
       version '%{old}'. To update to version '%{new}',
       destroy and recreate your machine.
+    box_outdated_metadata_download_error: |-
+      There was a problem while downloading the metadata for your box
+      to check for updates. This is not an error, since it is usually due
+      to temporary network problems. This is just a warning. The problem
+      encountered was:
+
+      %{message}
+
+      If you want to check for box updates, verify your network connection
+      is valid and try again.
     box_outdated_metadata_error_single: |-
       Error loading box metadata while attempting to check for
       updates: %{message}

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

@@ -153,6 +153,17 @@ describe Vagrant::Action::Builtin::BoxCheckOutdated do
       expect(env[:box_outdated]).to be_false
     end
 
+    it "does nothing if metadata download fails" do
+      expect(box).to receive(:has_update?).and_raise(
+        Vagrant::Errors::BoxMetadataDownloadError.new(message: "foo"))
+
+      expect(app).to receive(:call).once
+
+      subject.call(env)
+
+      expect(env[:box_outdated]).to be_false
+    end
+
     it "raises error if has_update? errors" do
       expect(box).to receive(:has_update?).and_raise(Vagrant::Errors::VagrantError)