Terraform 1.5 to 1.16: import, removed and check blocks, and what else changed

Terraform 1.x keeps backward compatibility for configurations, so most upgrades within 1.x need no code changes. What changed since 1.5 is mainly new language blocks that move one-off CLI state surgery into reviewed code.

New blocks by version

All of them in one configuration

cat > main.tf <<'EOF'
resource "terraform_data" "app" {
  input = "v1"
}
moved {
  from = terraform_data.old
  to   = terraform_data.app
}
removed {
  from = terraform_data.legacy
  lifecycle {
    destroy = false
  }
}
check "input_is_set" {
  assert {
    condition     = terraform_data.app.input != ""
    error_message = "input must not be empty"
  }
}
import {
  to = terraform_data.imported
  id = "abc"
}
resource "terraform_data" "imported" {}
EOF
terraform init -input=false -no-color >/dev/null
terraform version | head -1
terraform validate -no-color
terraform plan -no-color -input=false | grep '^Plan:'

Terraform v1.16.6
Success! The configuration is valid.

Plan: 1 to import, 1 to add, 0 to change, 0 to destroy.

Upgrade checklist

1. Read the "UPGRADE NOTES" sections of the changelog for each minor version you skip.
2. Raise required_version in shared modules only when they use a new feature.
3. Run terraform init -upgrade and terraform plan with the new version; the plan should show no changes.
4. Commit .terraform.lock.hcl so every machine uses the same providers.