Kubernetes LoadBalancer Service not loadbalancing requests - kubernetes

Question

I have a simple microservice setup running in a minikube cluster. It is inspired by this example.
My setup includes a simple router microservice that contains a golang webserver. What I want to test now is the loadbalancing when there is more then one pod. But there seems to be no load-balancing whatsoever.
The kubernetes file for the microservices looks like this:
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: router
labels:
app: router
tier: router
spec:
replicas: 2
strategy: {}
template:
metadata:
labels:
app: router
tier: router
spec:
containers:
- image: {myregistry}/router
name: router
resources: {}
ports:
- name: target-port
containerPort: 8082
env:
- name: PORT
value: "8082"
status: {}
---
apiVersion: v1
kind: Service
metadata:
name: router
labels:
app: router
tier: router
spec:
type: LoadBalancer
selector:
app: router
tier: router
ports:
- port: 8082
name: http
targetPort: target-port
The skaffold config looks like this:
apiVersion: skaffold/v1beta2
kind: Config
build:
artifacts:
- image: {myregistry}/router
context: src/router/bin
tagPolicy:
gitCommit: {}
local:
push: false
deploy:
kubectl:
manifests:
- ./kubernetes/**.yaml
Kubernetes correctly deploys two pods. The output of kubectl get pods looks like this:
NAME READY STATUS RESTARTS AGE
router-7f75f6f9df-c8mgp 1/1 Running 0 14m
router-7f75f6f9df-k248m 1/1 Running 0 14m
From the skaffold dev log output I can see that every request is routed to the router-7f75f6f9df-c8mgp pod. Even with different browsers all requests end up at the exact same pod.
When I delete this pod there is even a slight downtime of the router microservice even though there is another pod running.
What could be the problem of this behavior?

Answer 1

minikube doesn't 'properly' support the LoadBalancer service type. It used to be commonplace to just use the NodePort or externalIP service type instead, however the official hello-minikube sample now states:
On cloud providers that support load balancers, an external IP address
would be provisioned to access the Service. On Minikube, the
LoadBalancer type makes the Service accessible through the minikube
service command
So effectively you should be able to use your minikube LoadBalancer service with: minikube service router
However there is a neat solution that was developed for bare-metal kubernetes clusters called metallb that may be able to help you test this in a better way on minikube.
You can install and configure it on minikube. E.g.
kubectl apply -f https://raw.githubusercontent.com/google/metallb/v0.8.1/manifests/metallb.yaml
Here are some blog posts where others have explained the setup and use of metallb with minikube for LoadBalancer support:
Blog Post 1
Blog Post 2
Here are the official docs.
Hope that helps!