Elastic Cloud on Kubernetes (ECK) automates the deployment and orchestration of the Elastic Stack on Kubernetes. Learn about the available options for underlying storage and the tradeoffs between local disks and network-attached volumes.

1. 1
The best way to run
Elastic on Kubernetes
ElasticON 2020
Sebastien Guilloux
Senior Software Engineer - ECK

2. 2
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3. Challenges
When running things on Kubernetes
• Resource management
– StatefulSets, Pods, Secrets, Services, PersistentVolumes
• Day-2 operations
– Configuration changes, version upgrades, scale up/down
• Stateful workloads
– Availability, consistency, volume management

4. ECK
Elastic Cloud on Kubernetes
Deploy
Elasticsearch, Kibana, APM Server,
Beats, Enterprise Search
On Kubernetes
Vanilla, Openshift, GKE, EKS, AKS
Simple integration
kubectl & k8s tooling
Advanced orchestration
Hot/warm/cold, dedicated masters
Smooth operations
Scale up/down, rolling upgrade, version upgrade

5. 5
Quickstart demo

6. apiVersion: elasticsearch.k8s.elastic.co/v1
kind: Elasticsearch
metadata:
name: quickstart
spec:
version: 7.9.0
nodeSets:
- name: master-nodes
count: 3
config:
node.master: true
- name: data-nodes
count: 2
config:
node.data: true
master-nodes
StatefulSet
master-nodes-1
Pod
master-nodes-0
PersistentVolume
master-nodes-1
PersistentVolume
master-nodes-2
PersistentVolume
master-nodes-0
Pod
master-nodes-2
Pod
data-nodes
StatefulSet
data-nodes-1
Pod
data-nodes-0
PersistentVolume
data-nodes-1
PersistentVolume
data-nodes-0
Pod
Behind the scenes
StatefulSets

7. PersistentVolumes
apiVersion: elasticsearch.k8s.elastic.co/v1
kind: Elasticsearch
metadata:
name: quickstart
spec:
version: 7.9.0
nodeSets:
- name: data-nodes
count: 3
config:
node.master: true
volumeClaimTemplates:
- metadata:
name: elasticsearch-data
spec:
resources:
requests:
storage: 1000Gi
storageClassName: gke-ssd
- name: master-nodes
count: 3
config:
node.data: true
Provision a 1000Gi SSD for each Pod
If the Pod is recreated (upgrade or
failure), the same volume is reattached
StorageClass

8. 8
Which storage
should I use?
Well, it depends...

9. 9
PersistentVolumes
implementations
Network-attached vs. Local

10. Network-attached PersistentVolumes
Node
Elasticsearch
Pod
Persistent
Volume
Node
• Can be (re)-attached to any host in the same
region
– Useful when re-creating a Pod on a different host
• Performance varies depending on the Cloud
provider implementation
• Examples
– gce-pd-standard, gce-pd-ssd (Google GKE
– aws-ebs-io1, aws-ebs-gp2 Amazon EKS
– azure-managed-default, azure-managed-premium
Azure AKS

11. • Bound to a single host
– Pod cannot be recreated on a different host
• Performance varies depending on the underlying hardware
• Generally not available out of the box
– Need some extra provisioning work
Local PersistentVolumes
Node
Elasticsearch
Pod
Local
volume

12. Local vs. Network-attached
Trade-offs
Availability / Performance / Cost / Operations
What NAS options does my Kubernetes provider offer?
NFS and object-storage based volumes are generally not a
good fit)
What local storage can be attached to the VMs?

13. Local vs. Network-attached
Trade-offs
Availability / Performance / Cost / Operations
Some network-attached volumes (GKE SSDs, AWS IO1) offer good
performance. Best performance can be achieved with local volumes NVME
SSDs). We observed a 0%75% improvement depending on the use case.
The use case (ingest, search, query, aggregations, etc.) matters a lot.
For example: CPU may be the bottleneck when benchmarking ingestion.
Make sure to benchmark (Rally) your use case before drawing conclusions.

14. Local vs. Network-attached
Trade-offs
Availability / Performance / Cost / Operations
Network-attached volumes: per GB-month / IOPS-month.
Local volumes: per mounted disk on the VM.

15. Local vs. Network-attached
Trade-offs
Availability / Performance / Cost / Operations
Network-attached volumes are simple to operate: a failed Pod
can be recreated immediately on a different host with the
same volume.
Local volumes are more complicated to operate.

16. 16
Local
PersistentVolumes
Operations

17. Local PersistentVolumes
Provisioning
• Static provisioning
– Pre-create PersistentVolume resources in advance: one per available disk or
partition
– Either manually (write YAML, or using the static provisioner
• Dynamic provisioning
– Automatically create the right PersistentVolume on-demand
– Volume quota is not always respected
– Requires an additional provisioner (TopoLVM, Rancher Local Path, OpenEBS)

18. Host failure
Pod status: Pending
Node
Local
volume
Remove Pod + PVC to recreate the Pod
elsewhere with a new empty volume.
Local PersistentVolumes

19. Conflicting upgrades
Local PersistentVolumes
Node
12GB
ES 8GB
Node
12GB
Local
volume
Local
volume
ES 16GB
Pending
Rolling upgrade
8GB -> 16GB
RAM
Node
32GB
Node
32GB

20. 20
Picking the right
solution

21. Picking the right solution
Decision tree
• Study available network-attached storage classes
– Performance, pricing
– Benchmark with your use case
• If not good enough, consider using local volumes
– Choose a volume provisioner (the static provisioner is a good start)
– Be aware of operational concerns

22. 22
The best way to run
Elastic on Kubernetes
ElasticON 2020
Sebastien Guilloux
Senior Software Engineer - ECK