Reuse specs across environments and services with minimal templating.

Overview

Variables can be declared in your specs and overridden at runtime. They resolve into Terraform variables so you can keep a single spec and tune it per environment.

Declare variables

Define inputs in your spec and reference them with ${var.<name>}:

variables:
  min_nodes: "2"
  max_nodes: "5"
modules:
  - type: aws_eks
    min_nodes: "${var.min_nodes}"
    max_nodes: "${var.max_nodes}"

Override at runtime

Use repeatable --var flags or environment variables:

pltf terraform apply -f env.yaml -e prod --var min_nodes=3 --var max_nodes=6
# or
PLTF_VAR_min_nodes=3 PLTF_VAR_max_nodes=6 pltf generate -f env.yaml -e prod

Environment-scoped variables

Service specs can declare per-environment variables under envRef:

envRef:
  name: prod
  path: ./env.yaml
  variables:
    containers: 5
modules:
  - type: aws_k8s_service
    min_containers: 1
    max_containers: "${var.containers}"

Parent outputs

Services can use environment outputs via ${parent.<output>}:

public_uri: "${parent.domain}/hello"

Placeholder catalog

• ${env_name}, ${layer_name} (intrinsics)
• ${module.<module_name>.<output_name>}
• ${parent.<output_name>} (service only)
• ${var.<name>} (declared variables or CLI/env overrides)

Notes

• Required variables without defaults must be provided via --var or env.
• Precedence: env vars → service envRef vars → CLI --var.
• Values stay in Terraform variables (not locals) to avoid leaking secrets.