External Load Balancing

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Last updated 3 years ago

This section continues from the previous section - make sure you do the tutorial in sequence.

There are primarily 2 ways to expose a Kubernetes Service on the public internet:

Type

Protocol

Locality

When to use?

TCP/UDP

Regional

Non-HTTP requests, or no need for a global load balancer. Connection to the Load Balancer is routed by public Internet to region of the load balancer.

HTTP(s)

Global

HTTP requests. GCP's L7 Load Balancer is a global load balancer - a single IP address can automatically route traffic to the nearest region within the GCP network.

External Network Load Balancer

Service YAML

To create an external network load balancer, simply change Kubernetes Service's type from clusterip to loadbalancer. Modify the k8s/service.yaml:

k8s/service.yaml

apiVersion: v1
kind: Service
metadata:
  name: helloworld
  labels:
    app: helloworld
  annotations:
    cloud.google.com/neg: '{"exposed_ports": {"8080":{}}}'
spec:
  ports:
  - name: 8080-8080
    port: 8080
    protocol: TCP
    targetPort: 8080
  selector:
    app: helloworld
  # Use LoadBalancer type instead of ClusterIP
  type: LoadBalancer

Deploy

Use kubectl command line to deploy the YAML file:

kubectl apply -f k8s/service.yaml

To verify the application is deployed, run :

kubectl get svc helloworld

You should see that the Service has a Cluster IP address, but also the External IP address with the initial value of <pending>. This is because, behind the scenes, Kubernetes Engine is provisioning a Google Cloud Network Load Balancer.

NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)    AGE
helloworld   ClusterIP   ...          <pending>     8080/TCP   7s

Connect

Continuously check the External IP address, until an IP address is assigned. Once the IP Address is assigned, you can connect to the External IP address, and it'll be load balanced to the helloworld service backend pods.

EXTERNAL_IP=$(kubectl get svc helloworld -ojsonpath="{.status.loadBalancer.ingress[0].ip}")
curl $EXTERNAL_IP:8080

Static IP Address

You can assign a static IP address to the Network Load Balancer.

Reserve a regional static IP address:

REGION=$(gcloud config get-value compute/region)
gcloud compute addresses create helloworld-service-ip --region=${REGION}

See the reserved IP address:

REGION=$(gcloud config get-value compute/region)
gcloud compute addresses describe helloworld-service-ip --region=${REGION} --format='value(address)'

Update the k8s/service.yaml to pin the Load Balancer IP address:

k8s/service.yaml

apiVersion: v1
kind: Service
metadata:
  name: helloworld
  labels:
    app: helloworld
spec:
  ports:
  - name: 8080-8080
    port: 8080
    protocol: TCP
    targetPort: 8080
  selector:
    app: helloworld
  type: LoadBalancer
  # Replace the value with the IP address you reserved
  loadBalancerIP: RESERVED_IP_ADDRESS

External HTTP Load Balancer

You can configure an external HTTP load balancer using Kubernetes Ingress. In order for the HTTP Load Balancer to find the backends, it's recommended to use container-native load balancing on Google Cloud.

Service YAML

In the k8s/service.yaml, use the cloud.google.com/neg annotation to enable Network Endpoint Group (NEG) in order to use container-native load balancing:

k8s/service.yaml

apiVersion: v1
kind: Service
metadata:
  name: helloworld
  labels:
    app: helloworld
  # Add the NEG annotation to enable Network Endpoint Group
  # in order to use container-native load balancing
  annotations:
    cloud.google.com/neg: '{"ingress": true}'
spec:
  ports:
  - name: 8080-8080
    port: 8080
    protocol: TCP
    targetPort: 8080
  selector:
    app: helloworld
  type: ClusterIP

Ingress YAML

Create a Kubernetes Ingress configuration that will create the HTTP Load Balancer. Create a k8s/ingress.yaml:

k8s/ingress.yaml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: helloworld
spec:
  rules:
  - http:
      paths:
      - path: /*
        backend:
          service:
            name: helloworld
            post:
              number: 8080

Deploy

Use kubectl command line to deploy the YAML files:

# Delete the existing service because it may contain a node port:
kubectl delete -f k8s/service.yaml

# Redeploy the service
kubectl apply -f k8s/service.yaml

# Deploy the ingress
kubectl apply -f k8s/ingress.yaml

To verify the Ingress is deployed:

kubectl get ingress helloworld

You should see that the Ingress has an IP address provisioned:

NAME         HOSTS   ADDRESS         PORTS   AGE
helloworld   *       ...             80      81s

Many Google Cloud components are being configured behind the scenes to enable global load balancing. It'll take a few minutes before the address is accessible. Use kubectl describe to see the current status:

kubectl describe ingress helloworld

Initially, you may see:

Name:             helloworld
Namespace:        default
Address:          ...
Default backend:  helloworld:8080 (...)
Rules:
  Host  Path  Backends
  ----  ----  --------
  *     *     helloworld:8080 (...)
Annotations:
  ...
  ingress.kubernetes.io/backends:  {"...":"Unknown"}

When the annotation value of ingress.kubernetes.io/backends is Unknown, it means that the backend is not yet accessible.

Re-check the status until the backend becomes HEALTHY.

Name:             helloworld
Namespace:        default
Address:          ...
Default backend:  helloworld:8080 (...)
Rules:
  Host  Path  Backends
  ----  ----  --------
  *     *     helloworld:8080 (...)
Annotations:
  ...
  ingress.kubernetes.io/backends:  {"...":"HEALTHY"}

Connect

You can then use the IP address to connect:

EXTERNAL_IP=$(kubectl get ingress helloworld -ojsonpath="{.status.loadBalancer.ingress[0].ip}")
curl $EXTERNAL_IP

Static IP Address

By default, the Ingress IP address is ephemeral - it'll change if you ever delete and recreate the Ingress. You can associate the Ingress with a static IP address instead.

Global Static IP Address

Reserve a global static IP address:

gcloud compute addresses create helloworld-ingress-ip --global

See the static IP address you reserved:

gcloud compute addresses describe helloworld-ingress-ip --global \
  --format='value(address)'

Configurations

In k8s/ingress.yaml, use the kubernetes.io/ingress.global-static-ip-name annotation to specify the IP name:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: helloworld
  annotations:
    kubernetes.io/ingress.global-static-ip-name: "helloworld-ingress-ip"
spec:
  rules:
  - http:
      paths:
      - path: /*
        backend:
          service:
            name: helloworld
            post:
              number: 8080

Deploy

Deploy the Ingress:

kubectl apply -f k8s/ingress.yaml

Continuously check the IP address to be updated. It'll take several minutes for the IP address to update:

kubectl get ingress helloworld

SSL Certificate

In order to use a SSL certificate to serve HTTPs traffic, you must use a real fully qualified domain name and configure it to point to the IP address. If you don't have a real domain, then you can use xip.io.

EXTERNAL_IP=$(kubectl get ingress helloworld -ojsonpath="{.status.loadBalancer.ingress[0].ip}")
DOMAIN="${EXTERNAL_IP}.xip.io"
curl $DOMAIN

echo $DOMAIN

You can provision the External HTTP(s) Load Balancer using Ingress with a Managed Certificate, or you can provide your own Self-Managed Certificate.

Managed Certificate

Google Cloud can automatically provision a certificate for your domain name when using the External HTTP(s) Load Balancer.

Create a new k8s/certificate.yaml:

EXTERNAL_IP=$(kubectl get ingress helloworld -ojsonpath="{.status.loadBalancer.ingress[0].ip}")
DOMAIN="${EXTERNAL_IP}.xip.io"

cat << EOF > k8s/certificate.yaml
apiVersion: networking.gke.io/v1
kind: ManagedCertificate
metadata:
  name: helloworld-certificate
spec:
  domains:
  # Replace the value with your domain name
  - ${DOMAIN}
EOF

k8s/certificate.yaml

apiVersion: networking.gke.io/v1
kind: ManagedCertificate
metadata:
  name: helloworld-certificate
spec:
  domains:
  # Replace the value with your domain name
  - YOUR_DOMAIN_NAME

In k8s/ingress.yaml, use the networking.gke.io/managed-certificates annotation to associate the certificate:

k8s/ingress.yaml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: helloworld
  annotations:
    kubernetes.io/ingress.global-static-ip-name: "helloworld-ingress-ip"
    # Associate the ingress with the certificate name
    networking.gke.io/managed-certificates: "helloworld-certificate"
spec:
  rules:
  - http:
      paths:
      - path: /*
        backend:
          service:
            name: helloworld
            post:
              number: 8080

Deploy both files:

kubectl apply -f k8s/certificate.yaml
kubectl apply -f k8s/ingress.yaml

It may take several minutes to provision the certificate. Check the Managed Certificate status:

kubectl describe managedcertificate helloworld-certificate

Wait until the Certificate Status becomes ACTIVE:

Name:         helloworld
Namespace:    default
...
Status:
  Certificate Name:    ...
  Certificate Status:  Active
...

You can then use HTTPs to connect:

EXTERNAL_IP=$(kubectl get ingress helloworld -ojsonpath="{.status.loadBalancer.ingress[0].ip}")
DOMAIN="${EXTERNAL_IP}.xip.io"

curl "https://${DOMAIN}"

curl https://YOUR_DOMAIN_NAME

See Using Google-managed SSL certificates for more details.

Self-Managed Certificate

You can configure the Ingress to serve with your own SSL certificate. Usually you would already have a certificate/key pair.

If you don't already have one, you can provision a self-signed certificate for non-production use.

EXTERNAL_IP=$(kubectl get ingress helloworld -ojsonpath="{.status.loadBalancer.ingress[0].ip}")
DOMAIN="${EXTERNAL_IP}.xip.io"

mkdir -p cert/

# Generate a key
openssl genrsa -out cert/helloworld-tls.key 2048

# Generate a certificate signing request
openssl req -new -key cert/helloworld-tls.key \
  -out cert/helloworld-tls.csr \
  -subj "/CN=${DOMAIN}"

# 
openssl x509 -req -days 365 -in cert/helloworld-tls.csr \
  -signkey cert/helloworld-tls.key \
  -out cert/helloworld-tls.crt

Create a Kubernetes Secret to hold the certificate/key pair:

kubectl create secret tls helloworld-tls \
  --cert cert/helloworld-tls.crt --key cert/helloworld-tls.key \
  --dry-run -oyaml > k8s/tls-secret.yaml

Update the Ingress to refer to the secret for TLS certificate/key pair:

k8s/ingress.yaml

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: helloworld
  annotations:
    kubernetes.io/ingress.global-static-ip-name: "helloworld-ingress-ip"
spec:
  # Associate with the TLS certificate/key pair by the secret name
  tls:
  - secretName: helloworld-tls
  rules:
  - http:
      paths:
      - path: /*
        backend:
          service:
            name: helloworld
            post:
              number: 8080

Deploy the configurations:

kubectl apply -f k8s/tls-secret.yaml
kubectl apply -f k8s/ingress.yaml

It will take several minutes for the new configuration to take effect.

You can then use HTTPs to connect. However, if you used a self-signed certificate, you will need to ignore certificate validation errors:

EXTERNAL_IP=$(kubectl get ingress helloworld -ojsonpath="{.status.loadBalancer.ingress[0].ip}")
DOMAIN="${EXTERNAL_IP}.xip.io"

curl -k "https://${DOMAIN}"

See Using multiple SSL certificates in HTTP(s) load balancing with Ingress for more details.