Kubernetes is a declarative system for automatically deploying, managing, and scaling applications and their dependencies. In this short talk, I'll demonstrate a small Scylla cluster running in Google Compute Engine via Kubernetes and our publicly-published Docker images.

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Automating Scylla deployments
with Kubernetes
Software engineer, ScyllaDB
Jesse Haber-Kucharsky

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Setting expectations
I have no expertise in Kubernetes, Google Compute Engine, or Docker.
Nonetheless, it was easy to get a basic deployment running.
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Why Kubernetes?

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Containers
Isolate application resources and its environment in self-contained
units.
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Kubernetes
Automate deploying, scaling, and managing collections of containers
comprising applications.
Formerly an internal service at Google, now open-source and widely
supported.
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Quick K8s*
overview
* I’m cool like that.

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Declarative structure
▪ Resources (like Pods and StatefulSets) are described declaratively
in YAML
▪ The system adjusts itself dynamically to match the specification
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Pod
▪ A logical host
▪ Executes (usually) a single container
▪ Dynamically bound to a single (virtual) machine in the cluster
▪ Ephemeral
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PersistentVolumes
▪ Describes storage resources
▪ Pods request use of volumes through PersistentVolumeClaims
▪ Can be created statically or dynamically based on claims
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StatefulSet
▪ A specification of many Pods and their PersistentVolumeClaims
▪ Assigns Pods dynamically to a static set of persistent identifiers
(scylla-0, scylla-1, …)
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Demo

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Goal
▪ Easily spin-up a Scylla cluster on K8s in Google Compute Engine
▪ Dynamically scale the size of the Scylla cluster with new nodes
joining automatically (through DNS)
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Creating a cluster
▪ The K8s install scripts work seamlessly with Google Compute
Engine
▪ Install the Google Cloud SDK
▪ Download K8s and cluster/kube-up.sh
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Getting a Scylla image
▪ K8s can pull Docker images from the public Docker Hub
▪ We can use the public scylladb/scylla:2.0.0 image unmodified
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Allocating storage
▪ A StorageClass specifies the type of physical storage and the
provisioner
▪ The built-in Google Compute Engine provisioner can dynamically
provision PersistentVolumes
▪ Volumes outlive any particular Pod
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Checking for readiness
▪ A ConfigMap can be used to distribute individual files to Pods
▪ ready-probe.sh is invoked by K8s and uses nodetool to check the
status
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Seeding the cluster
▪ New Scylla nodes need to know where to connect to join the
cluster
▪ DNS records are automatically created for the static names of a
StatefulSet
▪ No custom code (SeedProvider) in Scylla required!
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Demo
▪ Preview some of the resource YAML files
▪ Show the Scylla cluster status
▪ Add a new node to the cluster dynamically with K8s
▪ Observe the larger Scylla cluster
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Enraptured focus on my laptop screen
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More details
▪ See the full K8s specification and walk-through at
https://github.com/scylladb/scylla-code-samples
▪ Look for an upcoming blog post.
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References
▪ Scalable-multi-node Cassandra deployment on Kubernetes
(https://github.com/IBM/Scalable-Cassandra-deployment-on-Kubernetes/blob/m
aster/README.md)
▪ Running Kubernetes on google Compute Engine
(https://kubernetes.io/docs/getting-started-guides/gce/)
▪ Example: Deploying Cassandra with Stateful Sets
(https://kubernetes.io/docs/tutorials/stateful-application/cassandra/)
▪ Strategies for Running Stateful Workloads in Kubernetes: Pet Sets
(https://thenewstack.io/strategies-running-stateful-applications-kubernetes-pet-
sets/)
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THANK YOU
jhaberku@scylladb.com
@jhaberku
Please stay in touch
Any questions?