Rationale​

Terraform is used for writing our entire infrastructure stack as code.

The main reasons why we chose it over other alternatives are:

1. It is Open source.
2. It is Widely used by the community.
3. It Uses HCL, a very easy to learn structured configuration language.
4. It is not platform-bounded.
5. It has a stateless approach to infrastructure. There are no master machines, agents, or incremental infrastructure. Instead, infrastructure is regenerated from scratch every time it is required.
6. Due to its stateless approach, parity between development and production environments is assured.
7. It has hundreds of open source providers that give it full flexibility across many platforms.
8. It has thousands of open source modules that simplify writing infrastructure and avoiding repetition.
9. Deploying infrastructure usually takes no longer than a few minutes.

Alternatives​

The following alternatives were considered but not chosen for the following reasons:

1. Ansible: Deployments were too slow.
2. AWS CDK: It is platform-bounded.
3. AWS Cloudformation: It is platform-bounded.
4. Chef: It has a stateful approach to infrastructure, including a master machine, agents and mutable infrastructure.
5. Pulumi: It is not as widely used, resulting in less providers, modules and overall community support.
6. Puppet: It has a stateful approach to infrastructure, including a master machine, agents and mutable infrastructure.
7. SaltStack: It has a stateful approach to infrastructure, including a master machine, agents and mutable infrastructure.

Usage​

Used for every infrastructure piece like databases, DNS records, firewall rules, computing clusters, among others. Some examples are:

1. GitLab Runners
2. DNS
3. Kubernetes
4. Okta
5. Website

We do not use Terraform in:

1. AWS Redshift: Pending to implement
2. GitLab: Pending to implement
3. GitLab Runner Bastion: Pending to implement
4. Google Workspace: Pending to implement