providers/docker: build output [GH-3739]

CHANGELOG.md

@@ -10,6 +10,7 @@ IMPROVEMENTS:
   - guests/suse: Support NFS client install, rsync setup. [GH-4492]
   - guests/tinycore: Support changing host names. [GH-4469]
   - guests/windows: Hostname can be set without reboot. [GH-4687]
+  - providers/docker: Build output is now shown. [GH-3739]
   - providers/docker: Can now start containers from private repositories
       more easily. Vagrant will login for you if you specify auth. [GH-4042]
   - providers/docker: `stop_timeout` can be used to modify the `docker stop`

plugins/providers/docker/action/build.rb

@@ -1,9 +1,13 @@
 require "log4r"
 
+require "vagrant/util/ansi_escape_code_remover"
+
 module VagrantPlugins
   module DockerProvider
     module Action
       class Build
+        include Vagrant::Util::ANSIEscapeCodeRemover
+
         def initialize(app, env)
           @app = app
           @logger = Log4r::Logger.new("vagrant::docker::build")
@@ -37,9 +41,13 @@ module VagrantPlugins
             machine.ui.output(I18n.t("docker_provider.building"))
             image = machine.provider.driver.build(
               build_dir,
-              extra_args: machine.provider_config.build_args,
+              extra_args: machine.provider_config.build_args) do |type, data|
-            )
+              data = remove_ansi_escape_codes(data.chomp).chomp
-            machine.ui.detail("Image: #{image}")
+              env[:ui].detail(data) if data != ""
+            end
+
+            # Output the final image
+            machine.ui.detail("\nImage: #{image}")
 
             # Store the image ID
             image_file.open("w") do |f|

plugins/providers/docker/driver.rb

@@ -14,10 +14,10 @@ module VagrantPlugins
         @executor = Executor::Local.new
       end
 
-      def build(dir, **opts)
+      def build(dir, **opts, &block)
         args   = Array(opts[:extra_args])
         args   << dir
-        result = execute('docker', 'build', *args)
+        result = execute('docker', 'build', *args, &block)
         matches = result.scan(/Successfully built (.+)$/i)
         if matches.empty?
           # This will cause a stack trace in Vagrant, but it is a bug