terraform-locals.md

Terraform Locals

A Terraform local assigns a name to an expression to allow repeated usage. They can be thought of similar to a local variable, and as such, can often be replaced by one.

In TypeScript, a Terraform local is expressed by TerraformLocal.

const commonTags = new TerraformLocal(this, 'common_tags', {
  Service: 'service_name',
  Owner: 'owner'
});

new Instance(this, 'example', {
    tags: commonTags.expression
});

The TerraformLocal synthesizes to the following:

"locals": {
    "common_tags": {
      "Service": "service_name",
      "Owner": "owner"
    }
}
...
"resource": {
  "aws_instance": {
    "example": {
      "tags": "${local.common_tags}"
    }
  }
}