Terraform State Skill

Comprehensive guide to state management, remote backends, and state manipulation operations.

Backend Configuration

AWS S3 Backend

terraform {
  backend "s3" {
    bucket         = "company-terraform-state"
    key            = "prod/terraform.tfstate"
    region         = "us-east-1"
    encrypt        = true
    dynamodb_table = "terraform-locks"

    # Cross-account access
    role_arn = "arn:aws:iam::ACCOUNT:role/TerraformAccess"
  }
}

Azure Storage Backend

terraform {
  backend "azurerm" {
    resource_group_name  = "terraform-state-rg"
    storage_account_name = "tfstatecompany"
    container_name       = "tfstate"
    key                  = "prod.terraform.tfstate"
    use_azuread_auth     = true
  }
}

GCP Cloud Storage Backend

terraform {
  backend "gcs" {
    bucket = "company-terraform-state"
    prefix = "terraform/state"
  }
}

Terraform Cloud

terraform {
  cloud {
    organization = "my-org"

    workspaces {
      tags = ["app:my-app", "env:prod"]
    }
  }
}

State Locking

DynamoDB Lock Table

resource "aws_dynamodb_table" "terraform_locks" {
  name         = "terraform-locks"
  billing_mode = "PAY_PER_REQUEST"
  hash_key     = "LockID"

  attribute {
    name = "LockID"
    type = "S"
  }

  tags = {
    Purpose = "Terraform state locking"
  }
}

Workspace Strategies

Directory-Based (Recommended)

infrastructure/
├── environments/
│   ├── dev/
│   │   ├── main.tf
│   │   ├── backend.tf
│   │   └── terraform.tfvars
│   ├── staging/
│   └── prod/
└── modules/

CLI Workspaces

# Create and switch
terraform workspace new prod
terraform workspace select prod
terraform workspace list

# Use in config
locals {
  env_config = {
    dev  = { instance_type = "t3.micro" }
    prod = { instance_type = "t3.large" }
  }
  config = local.env_config[terraform.workspace]
}

State Operations

Import Resources

# Basic import
terraform import aws_instance.web i-1234567890

# Import into module
terraform import module.vpc.aws_vpc.main vpc-abc123

# Import with for_each
terraform import 'aws_instance.web["app-1"]' i-1234567890

# Generate config (Terraform 1.5+)
terraform plan -generate-config-out=generated.tf

Move Resources

# Rename resource
terraform state mv aws_instance.old aws_instance.new

# Move to module
terraform state mv aws_instance.web module.compute.aws_instance.web

# Move between states
terraform state mv -state-out=other.tfstate aws_instance.web aws_instance.web

Remove from State

# Remove without destroying
terraform state rm aws_instance.legacy

# Remove entire module
terraform state rm module.deprecated

State Commands

# List resources
terraform state list

# Show resource details
terraform state show aws_instance.web

# Pull remote state
terraform state pull > state.json

# Push state (DANGEROUS)
terraform state push state.json

Drift Detection

# Refresh and show drift
terraform apply -refresh-only

# Detailed plan with refresh
terraform plan -refresh=true

# Check for changes only
terraform plan -detailed-exitcode
# Exit codes: 0=no changes, 1=error, 2=changes

Troubleshooting

State Lock Issues

# Force unlock (only if confirmed stale!)
terraform force-unlock LOCK_ID

# Check DynamoDB for lock
aws dynamodb get-item \
  --table-name terraform-locks \
  --key '{"LockID":{"S":"path/to/state"}}'

Common Errors

Error	Cause	Solution
Error acquiring lock	Stale lock	Wait or force-unlock
Backend config changed	Config modified	terraform init -reconfigure
State out of sync	Manual changes	terraform apply -refresh-only
Resource already exists	Import needed	terraform import

Recovery Procedures

# Backup current state
terraform state pull > backup.json

# Verify backup
cat backup.json | jq '.resources | length'

# Restore if needed
terraform state push backup.json

Best Practices

1. Always use remote state - Never commit .tfstate
2. Enable state locking - Prevent concurrent modifications
3. Enable encryption - Protect sensitive data
4. Version state bucket - S3 versioning for recovery
5. Separate state per environment - Isolation and safety

Usage

Skill("terraform-state")

Related

• Agent: 03-terraform-state (PRIMARY_BOND)
• Skill: terraform-workspace (SECONDARY_BOND)