Expose the Spark History server UI

Without Ingress (MicroK8s only)

The Spark History server exposes a UI accessible at http://<spark-history-server-ip>:18080.

If you are running MicroK8s, you can directly expose it to the local network by enabling DNS

microk8s enable dns

and retrieve the Spark History server POD IP using

IP=$(kubectl get pod spark-history-server-k8s-0 -n spark --template '{{.status.podIP}}')

With Ingress

The Spark History server can be exposed outside a K8s cluster by means of an ingress. This is the recommended way in production for any K8s distribution. Exposing Kubernetes services through an ingress generally requires the cloud provider/infrastrucutre to have an external load balancer integrated with the Kubernetes cluster. Most cloud providers (such as AWS, Google and Azure) provide this integration out-of-the-box. If you are running on MicroK8s, make sure that you have enabled metallb, as shown in the “How-To Setup K8s” userguide.

Spark History server can be exposed outside of the K8s cluster using traefik-k8s charm. If COS is enabled, you can use the ingress already provided as part of the COS bundle. Otherwise, you can deploy one using

juju deploy traefik-k8s --channel latest/candidate --trust

Then, relate with the Spark History server charm

juju relate traefik-k8s spark-history-server-k8s

After the charms settle down into idle/active states, fetch the URL of the Spark History server with

juju run-action traefik-k8s/0 show-proxied-endpoints --wait

This should print a JSON with all the ingress endpoints exposed by the traefik-k8s charm. To also exposed the UI outside the local cloud network via a public domain or to enable TLS encryption, please refer to this userguide about integration of traefik-k8s with Route53 and Let’s Encrypt (note that this is currently only supported on AWS EKS only).