Export the Git revision to an environment variable

Rakefile

@@ -8,4 +8,3 @@ Rake::TestTask.new do |t|
 end
 
 task :default => [:test]
-

build/Gemfile

@@ -3,3 +3,4 @@ source 'https://rubygems.org'
 # Install omnibus software
 gem 'omnibus', github: 'servebox/omnibus', branch: 'package-name-override'
 gem 'omnibus-software', github: 'servebox/omnibus-software', branch: 'pin-cacerts'
+gem 'git_rev'

build/config/software/electric_sheep.rb

@@ -1,4 +1,5 @@
 require File.join(File.dirname(__FILE__), '../build')
+require 'git_rev'
 
 name "electric_sheep"
 
@@ -13,12 +14,13 @@
 relative_path "electric_sheep"
 
 build do
+  revision = GitRev::Sha.new(repository: packaging_directories[:root]).full
   env = with_standard_compiler_flags(with_embedded_path)
   gem "build electric_sheep.gemspec", env: env
   gem "install electric_sheep-#{ElectricSheep::VERSION}.gem \
     -n #{install_dir}/bin --no-ri --no-rdoc", env: env
   erb source: 'ruby_wrapper.erb',
     dest: "#{install_dir}/bin/ruby_wrapper",
-    vars: {install_dir: install_dir},
+    vars: {install_dir: install_dir, revision: revision},
     mode: 0755
 end

build/config/templates/electric_sheep/ruby_wrapper.erb

@@ -5,4 +5,6 @@ export RUBY_GC_MALLOC_LIMIT_MAX=16777216
 export RUBY_GC_OLDMALLOC_LIMIT_MIN=16777216
 export RUBY_GC_OLDMALLOC_LIMIT_MAX=33554432
 
+export ELECTRIC_SHEEP_REVISION=<%= revision %>
+
 exec <%= install_dir %>/embedded/bin/ruby <%= install_dir %>/bin/electric_sheep "$@"