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Deploy Your First Application

Purpose: For app developers, shows how to deploy a basic web application on an openCenter-managed cluster, covering repository setup through live traffic routing.

Outcome​

By the end of this tutorial you will have:

  • A running Deployment with two nginx replicas behind a ClusterIP Service.
  • An HTTPRoute that exposes the app through the cluster's Gateway API gateway.
  • A working local validation workflow using kustomize build and kubeconform.

Prerequisites​

RequirementWhy
Access to an openCenter-managed Kubernetes cluster with FluxCD runningFlux reconciles your manifests automatically
kubectl configured with a valid kubeconfig for the target clusterNeeded for verification steps
kustomize CLI (v5+)Local manifest rendering
kubeconformSchema validation before push
pre-commit (pip install pre-commit or brew install pre-commit)YAML linting
A Git repository the platform team has configured Flux to watchFlux pulls from your repo, not the other way around

If you don't have a Flux-watched repository yet, ask your platform team to create the GitRepository and Kustomization resources. See the FluxCD integration reference for the exact manifests they need.

Step 1 — Clone the example repository​

git clone https://github.com/<org>/openCenter-customer-app-example
cd openCenter-customer-app-example

The repository ships with two sample apps. This tutorial focuses on app1/, which uses raw Kubernetes manifests.

Step 2 — Review the directory layout​

.
├── kustomization.yaml          # Root: assembles gateway + apps
├── gateway-resources/
│   ├── gateway.yaml            # Shared Gateway with TLS listeners
│   └── kustomization.yaml
├── app1/
│   ├── namespace.yaml          # Dedicated namespace
│   ├── deployment.yaml         # nginx Deployment (2 replicas)
│   ├── service.yaml            # ClusterIP Service
│   ├── httproute.yaml          # Gateway API routing
│   ├── sample-selfsigned-issuer.yaml
│   ├── sample-selfsigned-ca.yaml
│   ├── sample-ca-issuer.yaml   # cert-manager ClusterIssuer
│   └── kustomization.yaml
└── app2/                       # Helm-based app (ignore for now)

The root kustomization.yaml composes gateway-resources/ and each app directory. Flux renders this the same way kustomize build . does locally.

Step 3 — Customize the hostname​

Open gateway-resources/gateway.yaml and replace the demo hostname with your cluster's domain:

listeners:
  - name: web-https
    port: 443
    protocol: HTTPS
    hostname: app1.<your-cluster-domain>   # ← change this

Then update app1/httproute.yaml to match:

spec:
  hostnames:
    - "app1.<your-cluster-domain>"         # ← same hostname

Both values must agree — the HTTPRoute attaches to the Gateway listener by sectionName and hostname.

Step 4 — Validate locally​

kustomize build .

This should print the full set of rendered manifests without errors. Pipe the output through kubeconform to catch schema issues:

kubeconform <(kustomize build .)

A clean run produces no output. Any validation errors print the resource name and field path.

Step 5 — Install and run pre-commit hooks​

pre-commit install
pre-commit run --all-files

The repository includes a .yamllint config that enforces 2-space indentation, 120-character line length, and strict truthy values. Fix any reported issues before committing.

Step 6 — Commit and push​

git add .
git commit -m "Configure app1 for <your-cluster-domain>"
git push origin main

Flux polls the repository on the interval configured in the GitRepository resource (typically 1 minute). After the next reconciliation cycle, your resources appear in the cluster.

Check your work​

Verify the Deployment rolled out:

kubectl get deployment web-app -n app1

Expected output (two ready replicas):

NAME      READY   UP-TO-DATE   AVAILABLE   AGE
web-app   2/2     2            2           45s

Verify the HTTPRoute is attached to the Gateway:

kubectl get httproute web-app -n app1

Check the PARENTS column shows customer-managed-gateway.

If the Deployment is not appearing, force a reconciliation:

flux reconcile kustomization customer-app --with-source

Then check the Flux kustomize-controller logs for errors:

kubectl logs -n flux-system deploy/kustomize-controller -f

Next steps​