Managing Load Balancer IPs

By default, when you create a Load Balancer for your cluster, it will be assigned a random public IP address. When you delete the Load Balancer, the IP address will also be deleted and cannot be retrieved to transfer to another Load Balancer service in your cluster.

However, it is possible to use flexible IP addresses with your cluster’s Load Balancer, to give you more control over the IPs being used. Flexible IP addresses can be kept in your account even if/when their associated Load Balancer is deleted. They can then be assigned to a new Load Balancer in the future.

You can view your existing Load Balancer flexible IP addresses, and create new ones, in the Scaleway console. Alternatively, use the API or other development tools.

Before you start

To complete the actions presented below, you must have:

• A Scaleway account logged into the console
• Owner status or IAM permissions allowing you to perform actions in the intended Organization
• Created a Kubernetes cluster

Reserve a Load Balancer flexible IP address via the API

Using the API

Ensure that you have created an API key and run this call:

curl -X POST \
  -H "X-Auth-Token: $SCW_SECRET_KEY" \
  -H "Content-Type: application/json" \
  -d '{}' \
  "https://api.scaleway.com/lb/v1/zones/$SCW_DEFAULT_ZONE/ips"

Using the console

1. From the Load Balancer Flexible IPs page of the Scaleway console, click Create flexible IP.

2. Choose the Availability Zone for your flexible IP, and click Create flexible IP.

Deploy a Load Balancer with your reserved IP

When creating a Load Balancer service via a yaml manifest, you can specify the reserved IP to use via the loadBalancerIP field. On the example below, the IP we reserved was 51.159.24.7, and this will be the Load Balancer’s public IP address:

apiVersion: v1
kind: Service
metadata:
  name: myloadbalancer
spec:
  type: LoadBalancer
  ports:
  - port: 8000
    name: http
    targetPort: 8000
  selector:
    app: mydeployment
  loadBalancerIP: 51.159.24.7

You can then create your Load Balancer with the kubectl create -f <name-of-manifest-file>.yaml command. When you run kubectl get svc you will see that its EXTERNAL-IP matches the IP specified in the yaml manifest. When you delete your LoadBalancer service, the flexible IP 51.159.24.7 will remain reserved in your account to be used with another Load Balancer in the future.

Modify your Load Balancer’s IP address after creation

To modify your Load Balancer’s IP address after creation, you must use the kubectl patch command. This updates the Load Balancer according to the arguments given.

You must have an existing Load Balancer flexible IP in your account, that is not attached to any other Load Balancer.

In the case that you have created a Load Balancer with the manifest above (with IP address 51.159.24.7) but wish to change its IP address to another available one, use the following command and replace 51.159.113.199 with your other available flexible IP address:

kubectl patch svc myloadbalancer --type merge --patch '{"spec":{"loadBalancerIP": "51.159.113.199"}}'

When you run kubectl get svc you will see that its EXTERNAL-IP matches the IP specified in the patch command.

Specify that your Load Balancer’s IP should not be deleted with the Load Balancer

As long as you have specified a loadBalancerIP for your LoadBalancer service, either via the original manifest or a patch afterwards, the IP address will not be deleted from your account, even if you delete the LoadBalancer service with a kubectl delete svc myloadbalancer command.

If you created the Load Balancer without specifying a loadBalancerIP in your manifest, but want to keep its current IP address in your account after deleting the Load Balancer, you can use a kubectl patch command to achieve this.

• Identify the IP address that was randomly assigned to the Load Balancer, either via the Scaleway console or via a kubectl get svc command. Let’s imagine that this IP address is 51.159.10.49.
• Run a patch command to add this as the loadBalancerIP address in the service definition: kubectl patch svc myloadbalancer --type merge --patch '{"spec":{"loadBalancerIP": "51.159.10.49"}}'

Now, even if you delete the Load Balancer, its IP address will be held in your account and you can use it with a different Load Balancer in the future.

Demonstrate how to move an IP address across Kubernetes services

In the example below, we will:

• Create a new Load Balancer with a reserved IP, by patching an existing ClusterIP service called tea-svc.
• Check the IP address was correctly set on this service and that this service is now a Load Balancer one.
• Delete the tea-svc service (showing that the IP address is not deleted).
• Create a new Load Balancer with the IP reserved beforehand, by patching the coffee-svc service.

These steps show how we can use a reserved IP on Load Balancer creation and then “move” this IP from one service to another.

# kubectl get svc
NAME         TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
coffee-svc   ClusterIP   10.32.102.89   <none>        80/TCP    9s
kubernetes   ClusterIP   10.32.0.1      <none>        443/TCP   3m56s
tea-svc      ClusterIP   10.32.57.52    <none>        80/TCP    9s
# kubectl patch svc tea-svc --type merge --patch '{"spec":{"loadBalancerIP": "51.159.24.7","type":"Load Balancer"}}'
service/tea-svc patched
# kubectl get svc
NAME         TYPE           CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
coffee-svc   ClusterIP      10.32.102.89   <none>        80/TCP         44s
kubernetes   ClusterIP      10.32.0.1      <none>        443/TCP        4m31s
tea-svc      Load Balancer   10.32.57.52    <pending>     80:32434/TCP   44s
# kubectl get svc
NAME         TYPE           CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
coffee-svc   ClusterIP      10.32.102.89   <none>        80/TCP         45s
kubernetes   ClusterIP      10.32.0.1      <none>        443/TCP        4m32s
tea-svc      Load Balancer   10.32.57.52    51.159.24.7   80:32434/TCP   45s
# kubectl delete svc tea-svc
service "tea-svc" deleted
# kubectl patch svc coffee-svc --type merge --patch '{"spec":{"loadBalancerIP": "51.159.24.7","type":"Load Balancer"}}'
service/coffee-svc patched
# kubectl get svc
NAME         TYPE           CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
coffee-svc   Load Balancer   10.32.102.89   <pending>     80:31094/TCP   100s
kubernetes   ClusterIP      10.32.0.1      <none>        443/TCP        5m27s
# kubectl get svc
NAME         TYPE           CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
coffee-svc   Load Balancer   10.32.102.89   51.159.24.7   80:31094/TCP   103s
kubernetes   ClusterIP      10.32.0.1      <none>        443/TCP        5m30s

As you can see, we have been able to keep the same IP on different Load Balancers. This allows, for instance, to keep the same DNS configuration and move it from one Load Balancer Instance type to another. We have also seen that Kapsule manages the configuration of your Load Balancer for you. The cloud controller manager is in charge of managing the complete lifecycle of your Load Balancer.