Make sure Dockerfile is kept up to date

The build system passes in the necessary build arguments, buts its
beneficial to have the Dockerfile keep up to date with what the latest
stable version is in case people want to build their own.

Signed-off-by: Tom Duffield <tom@chef.io>

1 files changed, 9 insertions, 0 deletions

diff --git a/Rakefile b/Rakefile
index a72da319c9..311639230b 100644
--- a/Rakefile
+++ b/Rakefile
@@ -68,6 +68,15 @@ task :register_eventlog do
   end
 end
 
+desc "Keep the Dockerfile up-to-date"
+task :update_dockerfile do
+  require "mixlib/install"
+  latest_stable_version = Mixlib::Install.available_versions("chef", "stable").last
+  text = File.read("Dockerfile")
+  new_text = text.gsub(/^ARG VERSION=[\d\.]+$/, "ARG VERSION=#{latest_stable_version}")
+  File.open("Dockerfile", "w+") { |f| f.write(new_text) }
+end
+
 begin
   require "chefstyle"
   require "rubocop/rake_task"