Common Terraform Modules

This repository contains common Terraform modules that are used across the Massachussetts Digital Services infrastructure.

Each module should have:

• A README.md describing what the module does and how to use it.
• A main.tf file.
• A variables.tf file, if it takes input variables.
• An outputs.tf file, if it produces outputs.

Packer

This repository uses Packer to build custom AMIs. To rebuild an AMI:

# Authenticate so credentials are available to packer.
aws-exec massgov
packer build packer/ecs_ssm.json
# Packer will build the AMI and output the ID.

Development Workflow

These Terraform modules are used by other Terraform code. Development happens in the develop branch. Once the code is tested and stable, use the following process to make a release:

• Merge develop to master
• Update the changelog to categorize items as being in the correct release. Commit this change directly to master.
• Tag a new release using Semantic versioning (breaking changes are a major release).
• Merge master back to develop

Contributing

When you update a module in this repository, please update CHANGELOG.md with a description of the change made to each module headed under a new version tag and the release date. For example, if the current version tag is 1.0.99 and you're planning to release changes to asg and ecscluster on January 1 2025, a possible CHANGELOG line might look like

## [1.0.100] - 2025-01-01

- [ASG] Replace `volume_encryption` and `volume_size` variables with `block_devices` variable
- [ECS Cluster] Add `include_ami_device_names` variable to allow importing block device specifications from AMI.

Once the change is squash-merged into 1.x, tag and push the commit associated with the new version:

git tag -a 1.0.100 -m 'Updates ASG and ECS modules to allow module consumers to import block device specs' <commit hash>
git push --tags