Splitting a Terraform Monolith into Smaller States

If your Terraform plans are slow, your blast radius is too wide, or multiple teams are stepping on each other's changes, it's time to split your monolith. See The Problem with Large Terraform States for how to diagnose whether you've reached that point. This guide walks through the process of breaking a monolithic Terraform state into smaller, focused states — and how Snap CD can manage the dependencies between them so you don't have to. The approach 1. Identify natural boundaries Look at your resources and group them by lifecycle and ownership. Common boundaries: Networking — VPCs, subnets, route tables, NAT gateways. Changes rarely, underpins everything. DNS — Zones, records. Usually owned by a platform team. Compute — Kubernetes clusters, VM scale sets, container services. Changes more often, depends on networking. Application infrastructure — Databases, caches, queues, storage accounts. Owned by application teams. Monitoring — Dashboards, alerts, log sinks. Changes frequently, depends on everything but nothing depends on it. A useful test: if two resources would never be changed in the same PR by the same person, they probably belong in different states. 2. Map the dependencies Before you move anything, draw the dependency graph. Which groups produce values that other groups consume? networking dns │ ▲ ▼ │ compute ──────────►─┘ │ ▼ application │ ▼ monitoring The outputs that cross these boundaries are what you'll need to wire up after the split. Typical examples: Networking → Compute: vpc_id , private_subnet_ids Compute → DNS: load_balancer_ip Compute → Application: cluster_endpoint , cluster_ca_certificate Application → Monitoring: database_id , cache_name 3. Use terraform state mv to migrate resources Terraform's state mv command lets you move resources from one state to another without destroying and recreating them. # Initialize the destination state cd modules/networking terraform init # Move resources from the monolith to the new state terraform state mv \