Yaffle Automatic Preview Isolation Demo

One Terraform workspace demonstrates the complete Yaffle product loop:

1. Open a pull request.
2. Yaffle materializes an isolated resource name for pr-{number}.
3. The preview plans and applies without changing repository source.
4. Merge the pull request.
5. Yaffle destroys the preview and applies the original unsuffixed name to production.

The Story

The repository configures one stable filename:

variables.resource_name = "yaffle-product-demo"

The Terraform source uses that value directly:

resource "local_file" "demo" {
  filename = var.resource_name
}

Yaffle treats the same source differently according to environment ownership:

Event	Environment	Materialized filename
Pull request opened or updated	pr-{number}	yaffle-product-demo-{stable-suffix}
Pull request closed	pr-{number}	Preview resource destroyed
Push to main	production	yaffle-product-demo

The suffix is deterministic for the organization, repository, workspace, and environment. Yaffle adds it only inside the immutable execution artifact. It does not rewrite main.tf.

Run The Product Demo

Prerequisite: install the Yaffle GitHub App for this repository and connect it to your Yaffle organization.

1. Create a branch.
2. Change variables.demo_message in yaffle.toml.
3. Open a pull request.
4. Watch the Yaffle check create and apply the pr-{number} preview.
5. Inspect the configured_filename, materialized_filename, and environment outputs.
6. Merge the pull request.
7. Watch Yaffle destroy the preview and run the named production environment.

The pull-request output should show the configured name and materialized name diverging. The production output should show both names as yaffle-product-demo.

Why local_file?

The demo needs no cloud account, credentials, or billable infrastructure. The exact hashicorp/local 2.5.3 strategy exercises provider resolution, source transformation, artifact verification, plan, apply, outputs, and destroy.

The generated file exists only on the ephemeral runner. This is a product-mechanics demonstration, not a recommendation to manage durable infrastructure with local_file.

Validate Locally

tofu -chdir=infra/preview-isolation fmt -check
tofu -chdir=infra/preview-isolation init -backend=false -lockfile=readonly
tofu -chdir=infra/preview-isolation validate