Terraform Cascade

Demo

Overview

Terraform Cascade is a terraform-like tool that allows you to manage multiple terraform projects.

It's made to be fully compatible with terraform, so you can use it as a drop-in replacement. However, it requires the terraform binary to be available in the PATH.

Design

It works with a very opinionated design:

• Every project is inside a deep directory structure.
• To define a project, you only need to place a backend.tf file in that directory.
• In each layer, will be executed in the following order:
  1. Current directory (only when it has a backend.tf file)
  2. Whole base directory (with its layer)
  3. Other directories (with its layer)

Usage

Build

docker build -t cascade .

Run example

cd samples/basic/ # Some sample project that has dependencies between layers

# Full dependency tree in order
docker run -it --rm -v $(pwd):/w -v $(pwd)/tmp:/tmp -w /w cascade init --cascade-recursive
docker run -it --rm -v $(pwd):/w -v $(pwd)/tmp:/tmp -w /w cascade apply --cascade-recursive --auto-approve

# Full dependency tree in parallel
docker run -it --rm -v $(pwd):/w -v $(pwd)/tmp:/tmp -w /w/dev cascade apply --cascade-recursive --auto-approve

Generated infra

$ tree -a -I .terraform tmp/cascade
tmp/cascade
├── dev
│   ├── .account
│   ├── s3
│   │   └── .s3
│   └── vpc
│       ├── .vpc
│       └── eks
│           └── .eks
├── ops
│   ├── .account
│   └── vpc
│       └── .vpc
└── prod
    ├── .account
    └── vpc
        ├── .vpc
        └── eks
            └── .eks

Generated terraform states

$ tree -a tmp/cascade/.terraform/
tmp/cascade/.terraform/
├── base.tfstate
├── dev_base.tfstate
├── dev_eks.tfstate
├── ops_base.tfstate
├── prod_base.tfstate
└── prod_eks.tfstate