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A developer opens a pull request and gets an app — a golden path built from a template repo, a CRD, and Flux, with no portal anywhere in it

Artifact — a working golden path with no portal: a template repo a developer copies, a P4 CRD they fill in one instance of, and Flux reconciling it into a running app — so "I want an app" becomes a pull request and the pull request becomes a deployment, with nothing a human has to click. The claim to test is that the whole self-service loop is three things you already have, not a product you install.

Rests on — the Flux delivery path, which reconciles the CRD instance; and P4's CRD-plus-controller, which is the "one kind the developer fills in."

Topology — platform, continued.

Read — the module framing, the judgement module. This exercise builds the path; reading Backstage is where the contrast that gives it meaning lives.

Build — a template repo, a CRD the developer instantiates, and Flux wiring the instance to a real app:

# the developer's whole interface: copy the template, edit one file, open a PR
# template repo holds: an <App> CR instance + a Kustomization that Flux already watches
cat > my-app.yaml <<'YAML'
apiVersion: platform.example.com/v1
kind: App
metadata: {name: checkout, namespace: team-a}
spec: {image: checkout:1.4.0, replicas: 2, port: 8080}
YAML
# a PR merging this is the entire developer action; the controller + Flux do the rest
kubectl get app checkout -n team-a
kubectl get deploy,svc -n team-a -l app=checkout   # emitted by the controller, not written by the developer

Verify from outside — hand the template repo to a fresh consumer (or your past self) and time them from clone to running app. If they had to touch a Deployment, a Service, or a kubectl apply, the golden path leaked its implementation and is not one. One edited file and one merged PR is the pass condition.

Expect — a developer who names an app and gets an app, having seen one CRD instance and no Kubernetes primitive. This is the platform-as-product claim made concrete, and it is the capstone in miniature — the capstone adds a database, ingress, and a tenant boundary to the same shape.

Write down — the golden path as it exists (template repo + CRD + Flux), and the one developer action that drives it. This is one input to the failure-mode catalogue.

Footprint note — the controller is one small P4-style Deployment; no measurable addition to platform beyond the app it emits.

Teardown — delete the App instance and let Flux prune what it emitted; the CRD and controller stay for the leak drill and the capstone. The topology stays.