Lab 14 - Helm: install Traefik, releases and charts

Goal: install Helm, then use it on a real chart: Traefik, the entry point for Labs 15 and 16. Inspect, install, upgrade, roll back. Chapter: Helm

Install Helm

# 1 -
cd ~
curl -fsSL -o get_helm.sh https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-4
chmod 700 get_helm.sh && ./get_helm.sh
helm version

Look before you install

# 2 - the repository
helm repo add traefik https://traefik.github.io/charts
helm repo update
helm search repo traefik/traefik
helm search repo traefik/traefik --versions | head -5

# 3 - the chart's interface
helm show chart traefik/traefik | head -12
helm show values traefik/traefik | grep -n -A6 -E '^(service|gateway|providers):'

show values is the public interface of a chart. A setting that is not there does not exist - --set on an unknown key is silently ignored.

Prerequisite: Gateway API CRDs

Traefik will also serve Gateway API (Lab 16). The CRDs are not part of Kubernetes and the chart does not install them:

# 4 -
kubectl apply --server-side -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.6.1/standard-install.yaml
kubectl api-resources --api-group=gateway.networking.k8s.io

Install Traefik

# 5 - our values: NodePort (no cloud LB here) and Gateway API on
cat > traefik-values.yaml <<'YAML'
service:
  type: NodePort
ports:
  web:
    nodePort: 30080
  websecure:
    nodePort: 30443
providers:
  kubernetesGateway:
    enabled: true
gateway:
  listeners:
    web:
      namespacePolicy:
        from: All
YAML

# 6 - render first: what would be created?
helm template traefik traefik/traefik -n traefik -f traefik-values.yaml | grep '^kind:' | sort | uniq -c

# 7 - install
helm install traefik traefik/traefik -n traefik --create-namespace \
  -f traefik-values.yaml --wait
helm list -n traefik
kubectl get pods,svc -n traefik
kubectl get ingressclass,gatewayclass
kubectl get gateway -n traefik

One release gave you: the Traefik Deployment, a NodePort Service (80 -> 30080, 443 -> 30443), the IngressClass traefik, the GatewayClass traefik and a Gateway traefik-gateway.

# 8 - is anybody home?
curl -s -o /dev/null -w '%{http_code}\n' http://worker01:30080/

404 - Traefik answers, it just has no routes yet. That is success.

What Helm remembers

# 9 -
helm get values traefik -n traefik        # only what you overrode
helm get manifest traefik -n traefik | grep -E '^kind:' | sort | uniq -c
helm status traefik -n traefik

Upgrade and roll back

# 10 - change one value -> new revision
helm upgrade traefik traefik/traefik -n traefik -f traefik-values.yaml \
  --set deployment.replicas=2 --wait
kubectl get pods -n traefik
helm history traefik -n traefik

-f again! helm upgrade without your values file would fall back to the chart defaults - LoadBalancer, no Gateway API.

# 11 - roll back to revision 1
helm rollback traefik 1 -n traefik --wait
helm history traefik -n traefik           # rollback = revision 3
kubectl get pods -n traefik               # one replica again

Keep Traefik installed - Labs 15 and 16 use it.

Discovery

Infodiscover

Task A. Create your own chart myapp with helm create, render it and install it as release demo in namespace helmlab with 2 replicas.

Show one answer

helm create myapp
helm lint myapp
helm template demo ./myapp --set replicaCount=2 | grep -A3 'kind: Deployment'
helm install demo ./myapp -n helmlab --create-namespace --set replicaCount=2
kubectl get deploy -n helmlab

Task B. Change the image tag of demo to 1.27 without editing the chart, then find out which values the release uses.

Show one answer

helm show values ./myapp | grep -A4 '^image:'
helm upgrade demo ./myapp -n helmlab --reuse-values --set image.tag=1.27
helm get values demo -n helmlab

Clean up

helm uninstall demo -n helmlab --ignore-not-found
kubectl delete ns helmlab --ignore-not-found