Terraform Advanced — Workspace & Directory Exercises
Practice environment management patterns.
Exercise 1 — Workspace-Based Config
Task: Write a locals block that maps workspace names to instance types and CIDR blocks.
Answer
locals {
env = terraform.workspace
config = {
dev = { instance_type = "t3.micro", vpc_cidr = "10.0.0.0/16" }
staging = { instance_type = "t3.small", vpc_cidr = "10.1.0.0/16" }
prod = { instance_type = "m5.large", vpc_cidr = "10.2.0.0/16" }
}
current = local.config[local.env]
}
Exercise 2 — Directory Layout
Task: Design a directory layout for 3 environments (dev, staging, prod) with 2 services (vpc, eks) and a shared modules directory.
Answer
infra/
├── modules/
│ ├── vpc/
│ │ ├── main.tf
│ │ ├── variables.tf
│ │ └── outputs.tf
│ └── eks/
│ ├── main.tf
│ ├── variables.tf
│ └── outputs.tf
├── dev/
│ ├── vpc/
│ │ ├── main.tf # module "vpc" { source = "../../modules/vpc" }
│ │ └── terraform.tfvars
│ └── eks/
│ ├── main.tf
│ └── terraform.tfvars
├── staging/
│ ├── vpc/
│ └── eks/
└── prod/
├── vpc/
└── eks/
Exercise 3 — Migration
Task: You have a workspace-based setup. How do you migrate to directory-per-environment without downtime?
Answer
# 1. Create new directory with same config
$ mkdir -p environments/prod
# 2. Copy config
$ cp *.tf environments/prod/
# 3. Pull state from workspace
$ terraform workspace select prod
$ terraform state pull > /tmp/prod.tfstate
# 4. Init new directory with new backend key
$ cd environments/prod
$ terraform init -backend-config="key=prod/terraform.tfstate"
# 5. Push state to new location
$ terraform state push /tmp/prod.tfstate
# 6. Verify — plan should show no changes
$ terraform plan
# No changes.
# 7. Repeat for each workspace
Chapter Summary
- Workspaces: simple, one config, risk of applying to wrong env
- Directories: explicit, isolated, but code duplication
- Hybrid: directories for environments, workspaces for variations
- Terragrunt: DRY + isolated + dependency ordering (best for large teams)
- Production pattern: three-repo structure (modules, live, config)
