Infrastructure as code

Infrastructure as code. This buzz phrase is being thrown around and referenced by many reputable entities/persons. ThoughtWorks,, Puppet, Martin Fowler, and O’Reilly Publishing just to name a few of the top Google hits. This phrase is not just words that we say on our team. We believe this is important. To us, infrastructure as code means that any change, software, styling, firewall, system package, upstart script, etc., starts at the developer laptop on a Git branch. The change is made in source control, tested, and submitted as a pull request (PR) for peer review.

High level overview of our stack includes:

One more thing to clarify as far as terminology for our team. Our definition of environment is an AWS VPC which contains everything needed to be a production class system. This means that it will contain an RDS instance/cluster, a Mesos Cluster, a RabbitMQ cluser, and be running the necessary software to service requests to our platform.

When we want to build a new environment or deploy a change, we check out the desired Git commit SHA from our single source code repository and build an environment with Jenkins doing the heavy lifting. We have created several Jenkins jobs that feed in the appropriate parameters to the scripts checked into the source code. These will create the CloudFormation for our infrastructure, deploy the queue definitions, deploy the docker container versions/configuration via Marathon, and check the health of everything once completed.

Our process described above removes manual interactions. While we do have access to many interfaces that would allow us to make changes quickly, we as a team value the predictable/repeatable nature of our system. Before a change is deployed, our build pipe will build that environment run our full suite of unit and black box API functional tests against the environment to ensure all functionality works as expected. Tracking every change to our system via a Git commit, allows us to go back and know exactly when a change was made and (with good commit messages) for what reason the change was made. The PR process also ensures accountability and ownership of the team. In the end, everyone on the team is empowered to make a change to the system, the security team likes being able to see every change that was made to the system, and the team as a whole has confidence in building/maintaining our platform/system.

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