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Deploy the Application

We're going to deploy monachus/traefik-demo as our application. It will show a colored block for every Pod in the Deployment, and it has a number of options that we can configure via environment variables. We'll only focus on one, ICON_COLOR, which will give us a different color in staging and production.

You can learn more about this demo application from GitHub or Docker Hub.

Make the Directories​

We need to create traefik-demo in the apps directory for the base and our two environments.

mkdir -p apps/{base,staging,production}/traefik-demo

Configure the Base Manifests​

Start off like we did with Traefik Proxy in the infrastructure directory, first creating a base and then extending it to the staging environment with overrides.

Create each of the following files in their corresponding location in your directory.

namespace.yaml​

This creates the Namespace into which our application will be installed. We're using traefik-demo.

# apps/base/traefik-demo/namespace.yaml
---
apiVersion: v1
kind: Namespace
metadata:
  name: traefik-demo

deployment.yaml ​

This performs the installation of the application.

# apps/base/traefik-demo/deployment.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: traefik-demo
  name: traefik-demo
spec:
  selector:
    matchLabels:
      app: traefik-demo
  template:
    metadata:
      labels:
        app: traefik-demo
    spec:
      containers:
      - image: monachus/traefik-demo
        name: traefik-demo
        ports:
        - containerPort: 8080
        livenessProbe:
          initialDelaySeconds: 10
          periodSeconds: 5
          httpGet:
            path: "/"
            port: 8080

service.yaml​

This creates a ClusterIP service and maps port 80 to 8080 in the container.

# apps/base/traefik-demo/service.yaml
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: traefik-demo
  name: traefik-demo
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 8080
  selector:
    app: traefik-demo

ingressroute.yaml​

This creates an IngressRoute resource on port 80. The base template doesn't include any rules. Those will be added by the staging and production patches.

# apps/base/traefik-demo/ingressroute.yaml
---
apiVersion: traefik.containo.us/v1alpha1
kind: IngressRoute
metadata:
  name: traefik-demo-http
spec:
  entryPoints:
  - web

kustomization.yaml​

This is the instruction set for Kustomize itself.

# apps/base/traefik-demo/kustomization.yaml
---
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
namespace: traefik-demo
resources:
- namespace.yaml
- deployment.yaml
- service.yaml
- ingressroute.yaml

Configure the Staging Environment​

Configure the staging resources by copying these files to their corresponding locations.

deployment.yaml​

This adds an env key which sets the ICON_COLOR to blue.

# apps/staging/traefik-demo/deployment.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: traefik-demo
spec:
  template:
    spec:
      containers:
      - name: traefik-demo
        env:
        - name: ICON_COLOR
          value: blue

ingressroute.yaml​

Here we add the Rule to the ingressroute. Be sure to edit the Host information to change the IP to the IP of your staging cluster.

# apps/staging/traefik-demo/ingressroute.yaml
---
apiVersion: traefik.containo.us/v1alpha1
kind: IngressRoute
metadata:
  name: traefik-demo-http
spec:
  routes:
  - kind: Rule
    match: Host("traefik-demo.10.68.0.70.sslip.io")
    services:
    - name: traefik-demo
      port: 80

kustomization.yaml​

We'll pull in the base configuration and then patch the resources with our local manifests.

# apps/staging/traefik-demo/kustomization.yaml
---
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
namespace: traefik-demo
bases:
- ../../base/traefik-demo
patchesStrategicMerge:
- deployment.yaml
- ingressroute.yaml

Cluster Config​

Add the apps Kustomization below into the clusters/staging directory. Note that it depends on the infrastructure Kustomization, which ensures that if we brought all of this up at once, we'd get the CRDs, Traefik Proxy, and then the applications.

# clusters/staging/apps.yaml
---
apiVersion: kustomize.toolkit.fluxcd.io/v1beta2
kind: Kustomization
metadata:
  name: apps
  namespace: flux-system
spec:
  interval: 10m0s
  dependsOn:
  - name: infrastructure
  sourceRef:
    kind: GitRepository
    name: flux-system
  path: ./apps/staging
  prune: true
  wait: true

Add, Commit and Push​

Add these files, commit them to the repo, and then push them out to the remote. Wait for it to reconcile (or trigger it), and you should see the application deploy into traefik-demo.

PRO TIP: This is one of those times where you're reconcile flux-system so that it picks up the new apps Kustomization.

Once Flux is done, you should see apps in the output of flux get kustomization:

➤ flux get kustomization
NAME            READY MESSAGE                         REVISION      SUSPENDED
sources         True  Applied revision: main/4a1f097  main/4a1f097  False
crds            True  Applied revision: main/4a1f097  main/4a1f097  False
flux-system     True  Applied revision: main/4a1f097  main/4a1f097  False
infrastructure  True  Applied revision: main/4a1f097  main/4a1f097  False
apps            True  Applied revision: main/4a1f097  main/4a1f097  False

If you reach out to the URL you set in the ingressroute, you should see the Traefik gopher load on a blue background.

If you want to see Kubernetes load balancing in action, you can scale up the Deployment to more than one replica.

➤ kubectl scale deploy/traefik-demo --replicas=3 -n traefik-demo

deployment.apps/traefik-demo scaled

Because the replicas field isn't in Git, Flux won't try to change it to a different value during reconciliation. It only enforces the portions of the configuration that are in the repository.

Check Your Directory Structure​

Your repository should now look like this:

➤ tree .
.
├── apps
│   ├── base
│   │   └── traefik-demo
│   │       ├── deployment.yaml
│   │       ├── ingressroute.yaml
│   │       ├── kustomization.yaml
│   │       ├── namespace.yaml
│   │       └── service.yaml
│   ├── production
│   │   └── traefik-demo
│   └── staging
│       └── traefik-demo
│           ├── deployment.yaml
│           ├── ingressroute.yaml
│           └── kustomization.yaml
├── clusters
│   ├── production
│   └── staging
│       ├── apps.yaml
│       ├── crds.yaml
│       ├── flux-system
│       │   ├── gotk-components.yaml
│       │   ├── gotk-sync.yaml
│       │   └── kustomization.yaml
│       ├── infrastructure.yaml
│       └── sources.yaml
├── crds
│   ├── production
│   │   └── traefik-proxy
│   └── staging
│       └── traefik-proxy
│           └── kustomization.yaml
├── infrastructure
│   ├── base
│   │   └── traefik-proxy
│   │       ├── helmrelease.yaml
│   │       ├── kustomization.yaml
│   │       ├── kustomizeconfig.yaml
│   │       └── namespace.yaml
│   ├── production
│   │   └── traefik-proxy
│   └── staging
│       └── traefik-proxy
│           ├── helmrelease.yaml
│           ├── kustomization.yaml
│           └── values.yaml
└── sources
    └── helm
        └── traefik-proxy.yaml