elasticsearch on kubernetes - discovery of nodes - elasticsearch

Question

We are attempting to run Elasticsearch on top of a kubernetes / flannel / coreos cluster.
As flannel does not support multicast, we cannot use Zen multicast discovery to allow the nodes to find each other, form a cluster and communicate.
Short of hard-coding the IP addresses of all the kubernetes nodes into the ES-config-file, is there another method we can utilise to assist in discovery? Possibly using etcd2 or some other kubernetes-compatible discovery service?

Answer 1

Version 6.2.0 is supporting kubernetes auto discovery
update your elasticsearch.yml as following
discovery.zen.ping.unicast.hosts: "kubernetes service name"

Answer 2

There is a discovery plugin that uses the kubernetes API for cluster discovery:
https://github.com/fabric8io/elasticsearch-cloud-kubernetes
Install the plugin:
/usr/share/elasticsearch/bin/plugin -i io.fabric8/elasticsearch-cloud-kubernetes/1.3.0 --verbose
Create a Kubernetes service for discovery:
apiVersion: v1
kind: Service
metadata:
name: elasticsearch-cluster
spec:
ports:
- port: 9300
selector:
app: elasticsearch
And an elasticsearch.yml:
cloud.k8s.servicedns: elasticsearch-cluster
discovery.type: io.fabric8.elasticsearch.discovery.k8s.K8sDiscoveryModule

Answer 3

Place the containers into a Kubernetes Service. The Kubernetes API makes an 'endpoints' API available that lists the IP addresses of all of the members of a service. This endpoint set will dynamically shrink and grow as you scale the number of pods.
You can access endpoints with:
kubectl get endpoints <service-name>
or directly via the Kubernetes API, see:
https://github.com/kubernetes/kubernetes/blob/master/examples/cassandra/java/src/io/k8s/cassandra/KubernetesSeedProvider.java#L106
for an example of how this was done for Cassandra.

Answer 4

It worked for me only in this configuration.
Important! flannel must be enabled with vxlan.
cluster.yaml
network:
plugin: flannel
options:
flannel_backend_type: vxlan
elasticsearch.yaml
apiVersion: elasticsearch.k8s.elastic.co/v1
kind: Elasticsearch
metadata:
name: elastic-cluster
spec:
version: 7.0.1
nodeSets:
- name: node
count: 3
config:
node.master: true
node.data: true
node.ingest: true
xpack.ml.enabled: true
node.store.allow_mmap: true
indices.query.bool.max_clause_count: 100000
# Fixed flannel kubernetes network plugin
discovery.seed_hosts:
{{ range $i, $e := until (3 | int) }}
- elastic-cluster-es-node-{{ $i }}
{{ end }}
podTemplate:
spec:
containers:
- name: elasticsearch
env:
- name: ES_JAVA_OPTS
value: "-Xms4g -Xmx4g"
- name: READINESS_PROBE_TIMEOUT
value: "60"
resources:
requests:
memory: 5Gi
# cpu: 1
limits:
memory: 6Gi
volumeClaimTemplates:
- metadata:
name: elasticsearch-data
spec:
storageClassName: local-elasticsearch-storage
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 5G