extended Docker::Container with utility methods

lib/docker_client.rb

@@ -62,11 +62,9 @@ class DockerClient
 
   def self.destroy_container(container)
     container.stop.kill
-    if container.json['HostConfig']['PortBindings']
-      container.json['HostConfig']['PortBindings'].values.each do |configuration|
-        port = configuration.first['HostPort'].to_i
-        PortPool.release(port)
-      end
+    (container.port_bindings.try(:values) || []).each do |configuration|
+      port = configuration.first['HostPort'].to_i
+      PortPool.release(port)
     end
     container.delete(force: true)
   end

lib/docker_container_mixin.rb

@@ -0,0 +1,9 @@
+module DockerContainerMixin
+  def binds
+    json['HostConfig']['Binds']
+  end
+
+  def port_bindings
+    json['HostConfig']['PortBindings']
+  end
+end