Nordix/assign-lb-ip

Assigns an external load-balancer IP to a Kubernetes service

assign-lb-ip

Assigns loadBalancerIP address to a Kubernetes service for testing purposes.

This is normally done by the cloud provider or the metallb "controller". It is not possible to set the Status.loadBalancer.Ingress with kubectl (AFAIK), so this utility is needed.

Usage

Dual-stack phase 3 released in K8s v1.20 (alpha) is assumed.

Use assign-lb-ip -help to get a brief help printout.

The easiest way is to define the loadBalancerIP in the service manifest;

apiVersion: v1
kind: Service
metadata:
  name: mconnect-ipv6-lb
spec:
  ipFamilies:
  - IPv6
  selector:
    app: mconnect
  ports:
  - port: 5001
  type: LoadBalancer
  loadBalancerIP: 1000::8

The EXTERNAL-IP will still be in <pending> but you can now simply run assign-lb-ip to set it. Example;

$ kubectl get svc mconnect-ipv6-lb
NAME               TYPE           CLUSTER-IP        EXTERNAL-IP   PORT(S)          AGE
mconnect-ipv6-lb   LoadBalancer   fd00:4000::250b   <pending>     5001:32030/TCP   5m5s
$ assign-lb-ip -svc mconnect-ipv6-lb
$ kubectl get svc mconnect-ipv6-lb
NAME               TYPE           CLUSTER-IP        EXTERNAL-IP   PORT(S)          AGE
mconnect-ipv6-lb   LoadBalancer   fd00:4000::250b   1000::8       5001:32030/TCP   5m36s

assign-lb-ip will take the loadBalancerIP you specified in the manifest and set it as the "real" load-balancer IP.

You can also explicitly specify the load-balancer IP using the -ip option.

The service must have type: LoadBalancer and an explicitly specified -ip must work with net.ParseIP(). Other than that no checks are made.

You can also define a dual-stack service;

apiVersion: v1
kind: Service
metadata:
  name: mserver-preferdual-lb
spec:
  ipFamilyPolicy: PreferDualStack
  selector:
    app: mserver
  ports:
  - port: 5001
  type: LoadBalancer

Here PreferDualStack means that the service will be dual-stack if deployed in a dual-stack cluster. The "loadBalancerIP" field can not be used but a new loadBalancerIPs fiels is proposed (PR).

For dual-stack services a comma separated list of ip's is specified;

$ assign-lb-ip -svc mserver-preferdual-lb -ip 10.0.0.2,1000::2
$ kubectl get svc mserver-preferdual-lb
NAME                    TYPE           CLUSTER-IP    EXTERNAL-IP        PORT(S)                         AGE
mserver-preferdual-lb   LoadBalancer   12.0.22.230   10.0.0.2,1000::2   5001:31686/TCP,5003:31406/TCP   2m16s

Use the -clear option to remove LoadBalancerIPs.

Older dual-stack versions

Before K8s v1.20.0 only single-stack services could be specified but for both families. Syntax is sligtly different but assign-lb-ip works the same way.

apiVersion: v1
kind: Service
metadata:
  name: mconnect-ipv6-lb
spec:
  ipFamily: IPv6
  selector:
    app: mconnect
  ports:
  - port: 5001
  type: LoadBalancer
  loadBalancerIP: 1000::8

Build

GO111MODULE=on CGO_ENABLED=0 GOOS=linux go build -o assign-lb-ip \
  -ldflags "-extldflags '-static' -X main.version=$(git describe --dirty --tags)" \
  ./cmd/...