Terraforming all the things

Many companies continue to manaully create and manage their cloud infrastructure via web consoles. Documenting these procedures is challenging, especially since the interfaces are always evolving. Reviewing the changes is also difficult, and it often involves having a coworker watching over your shoulder. Rolling back a bad change requires deleting your current work and attemtping to manually re-create the old infrastructure from memory. Scaling or deploying the infrastructure to new environments also often involves manually re-creating it.

Hashicorp's Terraform allows for the management of infrastructure as code. While a growing number of groups have started to utilize this tool, most are only just beginning to scratch the surface of its potential. Yes, Terraform can be used to create and manage resources in AWS and other cloud providers. However, thanks to an ever growing number of providers, it can manage resources in many other popular cloud services. At Yelp, we use Terraform to manage our AWS resources, DNS records in NS1, CDN configuration in Fastly and Cloudflare, and our charts and dashboards in SignalFx.

This setup provides us with the ability to maintain our infrastructure as code in a version control system that can be put through standard code review flows. If we discover an issue, we can revert to an older, working commit and restore our infrastructure to that point in time. Documentation can include code snippets that can be easily copied/pasted in an error free manner. Finally, resources managed by one Terraform provider can benefit from and utilize information from resources managed by another provider. This means that launching a new AWS EC2 instance can automatically update the necessary DNS records in NS1, and then create a dashboard filled with customized charts designed to monitor the instance.