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OpenViSUS Documentation

Table of contents

  1. Introduction
  2. Prerequisites
  3. Create K8s deployment
  4. Create K8s Service
  5. Create ingress (OPTIONAL needed only for real cluster)

Introduction

This tutorial shows how to run one or multiple modvisus with a frontend load balancer using Kubernetes (K8s).

See docs/powerpoint/Kubernetes.pptx for a graphical expolanation.

Prerequisites

If you are running on Windows, and would like to experiment with K8s, please follow https://learnk8s.io/installing-docker-kubernetes-windows; you should install WSL, Docker Desktop and minikube:

choco install minikube -y
minikube start

Make sure completition is enabled:

source <(kubectl completion bash)

And create a unique K8s namespace you will use for resource creation:

kubectl create namespace my-namespace
kubectl config set-context --current --namespace=my-namespace

Later on you can remove all resources with a simple by:

kubectl delete namespace my-namespace

Create K8s deployment

Create a mod-visus-deployment deployment for example using the following command:

kubectl create deployment mod-visus-deployment --image=visus/mod_visus:latest  --dry-run -o yaml > mod_visus_deployment.yaml

Edit the file and setup as needed (vi ./mod_visus_deployment.yaml)

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: mod_visus_deployment
  name: mod-visus-deployment
  namespace: openvisus
spec:
  replicas: 3 # scrgiorgio: it was 1, change have N instances with load balancing
  selector:
    matchLabels:
      app: mod_visus_deployment
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: mod_visus_deployment
    spec:
      # scrgiorgio: custom section for mounting nfs path in case you have some datasets to expose
      volumes:
      - name: datasets-volume
        hostPath:
          path: /mnt/c/projects/OpenVisus/datasets
      containers:
      - image: visus/mod_visus
        name: modvisus # scrgiorgio: change from mod_visus to modvisus , '_' character is not allowed
        
        # scrgiorgio:  custom section to configure datasets and ports 
        ports:                   
        - containerPort : 80   
        volumeMounts:
        - name: datasets-volume
          mountPath: /datasets # scrgiorgio: this is where mod_visus wants the datasets 
        env:                    
          - name: VISUS_DATASETS 
            value: /datasets  
        readinessProbe:
          httpGet:
            path: /mod_visus?action=list
            port: 80
        livenessProbe:
          httpGet:
            path: /
            port: 80

Finally create and inspect the deployment:

kubectl apply -f mod_visus_deployment.yaml  --record 
kubectl describe deployment mod-visus-deployment
kubectl get mod-visus-deployment -o wide
kubectl get pods -o wide
kubectl logs mod-visus-deployment
kubectl logs mod-visus-deployment-67d987676d-2vsvd # replace with the name of the logs

In case you don’t rememeber specific YAML sections of your file, you can use explain. For example:

kubectl explain Pod.spec.volumes

Or you can check the history of the deployment

kubectl rollout history deployment mod-visus-deployment
kubectl rollout status  deployment mod-visus-deployment

To get all the pods connected to the deployment:

kubectl get pods -o wide

To check if openvisus server are running you can create a temporary pod inside the cluster:

kubectl run -i --tty --rm tmp1 --image=busybox  -- sh

# change the IP address with one given from `kubectl get pods -o wide` command:
IP_ADDRESS=10.1.0.34 

wget -O- --no-verbose http://$IP_ADDRESS/mod_visus?action=list 
exit

Or you can connect to one of the server pod:

kubectl exec  deploy/mod-visus-deployment -i -t -- sh
apt-get install -y wget
wget -O- --no-verbose http://localhost:80/mod_visus?action=list
exit

To inspect logs from the outside:

kubectl logs  deployment/mod-visus-deployment

Create K8s Service

So far, no pods, nodes, deployment is already accessible from the outside. To do so you need to expose the deployment:

kubectl expose deployment mod-visus-deployment --port=80 --target-port=80 --name=mod-visus-service --type=NodePort --dry-run -o yaml > mod_visus_service.yaml

The edit the yaml file (vi mod_visus_service.yaml)

apiVersion: v1
kind: Service
metadata:
  creationTimestamp: null
  labels:
    app: mod-visus-deployment
  name: mod-visus-service
  namespace: openvisus # scrgiorgio: important to add
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
    nodePort: 30080 # scrgiorgio: set a static nodePort just for simplicity 
  selector:
    app: mod-visus-deployment
  type: NodePort

Then create the service using that file:

kubectl apply -f mod_visus_service.yaml --record

Inspect the service:

kubectl get service 
kubectl describe service mod-visus-service

Check all resources in openvisus:

kubectl get all  -o wide 
kubectl get all --all-namespaces -o wide

You can access the service from a temporary pod using the service name:

kubectl run -i --tty --rm tmp1 --image=busybox -- sh
wget -O- http://mod-visus-service/mod_visus?action=list

Or you can connect from external:

#if you don't know the nodePort (i.e. the port exposed to the external)
kubectl get service -o yaml | grep nodePort

wget -O- --no-verbose http://localhost:30080/mod_visus?action=list

Create ingress (OPTIONAL needed only for real cluster)

On minikube:

minikube addons enable ingress

Create a ` mod_visus_ingress.yaml` file for ingress:

apiVersion: networking.k8s.io/v1beta1 # for versions before >1.16 use extensions/v1
kind: Ingress
metadata:
  name: mod-visus-ingress
  namespace: openvisus
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
  - host: localhost
    http:
      paths:
      - path: /
        backend:
          serviceName: mod-visus-service
          servicePort: 80 # note: this is the service port, not the nodePort (you could use even a Cluster service instead of NodePort service?)

Create/ Inspect/ Debug the ingress:

kubectl apply -f mod_visus_ingress.yaml
kubectl describe ingress mod-visus-ingress 
kubectl get ingress

See if it works:

wget -O- --no-verbose http://localhost:80/mod_visus?action=list

bectl get ingress


See if it works:

wget -O- –no-verbose http://localhost:80/mod_visus?action=list ```