Allow dynamic accessory files to reference declared ENVs

lib/mrsk/configuration/accessory.rb

@@ -74,12 +74,19 @@ class Mrsk::Configuration::Assessory
 
     def expand_local_file(local_file)
       if local_file.end_with?("erb")
-        read_dynamic_file(local_file)
+        with_clear_env_loaded { read_dynamic_file(local_file) }
       else
         Pathname.new(File.expand_path(local_file)).to_s
       end
     end
 
+    def with_clear_env_loaded
+      (env["clear"] || env).each { |k, v| ENV[k] = v }
+      yield
+    ensure
+      (env["clear"] || env).each { |k, v| ENV.delete(k) }
+    end
+
     def read_dynamic_file(local_file)
       StringIO.new(ERB.new(IO.read(local_file)).result)
     end

test/configuration/accessory_test.rb

@@ -98,7 +98,8 @@ class ConfigurationAccessoryTest < ActiveSupport::TestCase
     @deploy[:accessories]["mysql"]["files"] << "test/fixtures/files/structure.sql.erb:/docker-entrypoint-initdb.d/structure.sql"
     @config = Mrsk::Configuration.new(@deploy)
 
-    assert_equal "This was dynamically expanded", @config.accessory(:mysql).files.keys[2].read
+    assert_match "This was dynamically expanded", @config.accessory(:mysql).files.keys[2].read
+    assert_match "%", @config.accessory(:mysql).files.keys[2].read
   end
 
   test "directories" do

test/fixtures/files/structure.sql.erb

@@ -1 +1,2 @@
 <%= "This was dynamically expanded" %>
+<%= ENV["MYSQL_ROOT_HOST"] %>