Merge pull request #118 from danielmanesku/danielmanesku-docker

Adding Docker next to Vagrant

content/en/dev-prod-parity.md

@@ -71,6 +71,6 @@ Developers sometimes find great appeal in using a lightweight backing service in
 
 **The twelve-factor developer resists the urge to use different backing services between development and production**, even when adapters theoretically abstract away any differences in backing services. Differences between backing services mean that tiny incompatibilities crop up, causing code that worked and passed tests in development or staging to fail in production. These types of errors create friction that disincentivizes continuous deployment. The cost of this friction and the subsequent dampening of continuous deployment is extremely high when considered in aggregate over the lifetime of an application.
 
-Lightweight local services are less compelling than they once were. Modern backing services such as Memcached, PostgreSQL, and RabbitMQ are not difficult to install and run thanks to modern packaging systems, such as [Homebrew](http:https://mxcl.github.com/homebrew/) and [apt-get](https://help.ubuntu.com/community/AptGet/Howto). Alternatively, declarative provisioning tools such as [Chef](http:https://www.opscode.com/chef/) and [Puppet](http:https://docs.puppetlabs.com/) combined with light-weight virtual environments such as [Vagrant](http:https://vagrantup.com/) allow developers to run local environments which closely approximate production environments. The cost of installing and using these systems is low compared to the benefit of dev/prod parity and continuous deployment.
+Lightweight local services are less compelling than they once were. Modern backing services such as Memcached, PostgreSQL, and RabbitMQ are not difficult to install and run thanks to modern packaging systems, such as [Homebrew](http:https://mxcl.github.com/homebrew/) and [apt-get](https://help.ubuntu.com/community/AptGet/Howto). Alternatively, declarative provisioning tools such as [Chef](http:https://www.opscode.com/chef/) and [Puppet](http:https://docs.puppetlabs.com/) combined with light-weight virtual environments such as [Docker](https://www.docker.com/) and [Vagrant](http:https://vagrantup.com/) allow developers to run local environments which closely approximate production environments. The cost of installing and using these systems is low compared to the benefit of dev/prod parity and continuous deployment.
 
 Adapters to different backing services are still useful, because they make porting to new backing services relatively painless. But all deploys of the app (developer environments, staging, production) should be using the same type and version of each of the backing services.