README
¶
PLEASE NOTE: This document applies to the HEAD of the source tree
If you are using a released version of Kubernetes, you should refer to the docs that go with that version.
The latest 1.0.x release of this document can be found [here](http://releases.k8s.io/release-1.0/examples/elasticsearch/README.md).Documentation for other releases can be found at releases.k8s.io.
Elasticsearch for Kubernetes
This directory contains the source for a Docker image that creates an instance of Elasticsearch 1.5.2 which can be used to automatically form clusters when used with replication controllers. This will not work with the library Elasticsearch image because multicast discovery will not find the other pod IPs needed to form a cluster. This image detects other Elasticsearch pods running in a specified namespace with a given label selector. The detected instances are used to form a list of peer hosts which are used as part of the unicast discovery mechanism for Elasticsearch. The detection of the peer nodes is done by a program which communicates with the Kubernetes API server to get a list of matching Elasticsearch pods.
Here is an example replication controller specification that creates 4 instances of Elasticsearch.
apiVersion: v1
kind: ReplicationController
metadata:
labels:
name: music-db
namespace: mytunes
name: music-db
spec:
replicas: 4
selector:
name: music-db
template:
metadata:
labels:
name: music-db
spec:
containers:
- name: es
image: kubernetes/elasticsearch:1.1
env:
- name: "CLUSTER_NAME"
value: "mytunes-db"
- name: "SELECTOR"
value: "name=music-db"
- name: "NAMESPACE"
value: "mytunes"
ports:
- name: es
containerPort: 9200
- name: es-transport
containerPort: 9300
The CLUSTER_NAME variable gives a name to the cluster and allows multiple separate clusters to
exist in the same namespace.
The SELECTOR variable should be set to a label query that identifies the Elasticsearch
nodes that should participate in this cluster. For our example we specify name=music-db to
match all pods that have the label name set to the value music-db.
The NAMESPACE variable identifies the namespace
to be used to search for Elasticsearch pods and this should be the same as the namespace specified
for the replication controller (in this case mytunes).
Replace NAMESPACE with the actual namespace to be used. In this example we shall use
the namespace mytunes.
kind: Namespace
apiVersion: v1
metadata:
name: mytunes
labels:
name: mytunes
First, let's create the namespace:
$ kubectl create -f examples/elasticsearch/mytunes-namespace.yaml
namespaces/mytunes
Now you are ready to create the replication controller which will then create the pods:
$ kubectl create -f examples/elasticsearch/music-rc.yaml --namespace=mytunes
replicationcontrollers/music-db
Let's check to see if the replication controller and pods are running:
$ kubectl get rc,pods --namespace=mytunes
CONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICAS
music-db es kubernetes/elasticsearch:1.1 name=music-db 4
NAME READY STATUS RESTARTS AGE
music-db-5p46b 1/1 Running 0 34s
music-db-8re0f 1/1 Running 0 34s
music-db-eq8j0 1/1 Running 0 34s
music-db-uq5px 1/1 Running 0 34s
It's also useful to have a service with an load balancer for accessing the Elasticsearch cluster.
apiVersion: v1
kind: Service
metadata:
name: music-server
namespace: mytunes
labels:
name: music-db
spec:
selector:
name: music-db
ports:
- name: db
port: 9200
targetPort: es
type: LoadBalancer
Let's create the service with an external load balancer:
$ kubectl create -f examples/elasticsearch/music-service.yaml --namespace=mytunes
services/music-server
Let's check the status of the service:
$ kubectl get service --namespace=mytunes
NAME LABELS SELECTOR IP(S) PORT(S)
music-server name=music-db name=music-db 10.0.185.179 9200/TCP
Although this service has an IP address 10.0.185.179 internal to the cluster we don't yet have
an external IP address provisioned. Let's wait a bit and try again...
$ kubectl get service --namespace=mytunes
NAME LABELS SELECTOR IP(S) PORT(S)
music-server name=music-db name=music-db 10.0.185.179 9200/TCP
104.197.114.130
Now we have an external IP address 104.197.114.130 available for accessing the service
from outside the cluster.
Let's see what we've got:
$ kubectl get pods,rc,services --namespace=mytunes
NAME READY STATUS RESTARTS AGE
music-db-5p46b 1/1 Running 0 7m
music-db-8re0f 1/1 Running 0 7m
music-db-eq8j0 1/1 Running 0 7m
music-db-uq5px 1/1 Running 0 7m
CONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICAS
music-db es kubernetes/elasticsearch:1.1 name=music-db 4
NAME LABELS SELECTOR IP(S) PORT(S)
music-server name=music-db name=music-db 10.0.185.179 9200/TCP
104.197.114.130
NAME TYPE DATA
default-token-gcilu kubernetes.io/service-account-token 2
This shows 4 instances of Elasticsearch running. After making sure that port 9200 is accessible for this cluster (e.g. using a firewall rule for Google Compute Engine) we can make queries via the service which will be fielded by the matching Elasticsearch pods.
$ curl 104.197.114.130:9200
{
"status" : 200,
"name" : "Warpath",
"cluster_name" : "mytunes-db",
"version" : {
"number" : "1.5.2",
"build_hash" : "62ff9868b4c8a0c45860bebb259e21980778ab1c",
"build_timestamp" : "2015-04-27T09:21:06Z",
"build_snapshot" : false,
"lucene_version" : "4.10.4"
},
"tagline" : "You Know, for Search"
}
$ curl 104.197.114.130:9200
{
"status" : 200,
"name" : "Callisto",
"cluster_name" : "mytunes-db",
"version" : {
"number" : "1.5.2",
"build_hash" : "62ff9868b4c8a0c45860bebb259e21980778ab1c",
"build_timestamp" : "2015-04-27T09:21:06Z",
"build_snapshot" : false,
"lucene_version" : "4.10.4"
},
"tagline" : "You Know, for Search"
}
We can query the nodes to confirm that an Elasticsearch cluster has been formed.
$ curl 104.197.114.130:9200/_nodes?pretty=true
{
"cluster_name" : "mytunes-db",
"nodes" : {
"u-KrvywFQmyaH5BulSclsA" : {
"name" : "Jonas Harrow",
...
"discovery" : {
"zen" : {
"ping" : {
"unicast" : {
"hosts" : [ "10.244.2.48", "10.244.0.24", "10.244.3.31", "10.244.1.37" ]
},
...
"name" : "Warpath",
...
"discovery" : {
"zen" : {
"ping" : {
"unicast" : {
"hosts" : [ "10.244.2.48", "10.244.0.24", "10.244.3.31", "10.244.1.37" ]
},
...
"name" : "Callisto",
...
"discovery" : {
"zen" : {
"ping" : {
"unicast" : {
"hosts" : [ "10.244.2.48", "10.244.0.24", "10.244.3.31", "10.244.1.37" ]
},
...
"name" : "Vapor",
...
"discovery" : {
"zen" : {
"ping" : {
"unicast" : {
"hosts" : [ "10.244.2.48", "10.244.0.24", "10.244.3.31", "10.244.1.37" ]
...
Let's ramp up the number of Elasticsearch nodes from 4 to 10:
$ kubectl scale --replicas=10 replicationcontrollers music-db --namespace=mytunes
scaled
$ kubectl get pods --namespace=mytunes
NAME READY STATUS RESTARTS AGE
music-db-0n8rm 0/1 Running 0 9s
music-db-4izba 1/1 Running 0 9s
music-db-5dqes 0/1 Running 0 9s
music-db-5p46b 1/1 Running 0 10m
music-db-8re0f 1/1 Running 0 10m
music-db-eq8j0 1/1 Running 0 10m
music-db-p9ajw 0/1 Running 0 9s
music-db-p9u1k 1/1 Running 0 9s
music-db-rav1q 0/1 Running 0 9s
music-db-uq5px 1/1 Running 0 10m
Let's check to make sure that these 10 nodes are part of the same Elasticsearch cluster:
$ curl 104.197.114.130:9200/_nodes?pretty=true | grep name
"cluster_name" : "mytunes-db",
"name" : "Killraven",
"name" : "Killraven",
"name" : "mytunes-db"
"vm_name" : "OpenJDK 64-Bit Server VM",
"name" : "eth0",
"name" : "Tefral the Surveyor",
"name" : "Tefral the Surveyor",
"name" : "mytunes-db"
"vm_name" : "OpenJDK 64-Bit Server VM",
"name" : "eth0",
"name" : "Jonas Harrow",
"name" : "Jonas Harrow",
"name" : "mytunes-db"
"vm_name" : "OpenJDK 64-Bit Server VM",
"name" : "eth0",
"name" : "Warpath",
"name" : "Warpath",
"name" : "mytunes-db"
"vm_name" : "OpenJDK 64-Bit Server VM",
"name" : "eth0",
"name" : "Brute I",
"name" : "Brute I",
"name" : "mytunes-db"
"vm_name" : "OpenJDK 64-Bit Server VM",
"name" : "eth0",
"name" : "Callisto",
"name" : "Callisto",
"name" : "mytunes-db"
"vm_name" : "OpenJDK 64-Bit Server VM",
"name" : "eth0",
"name" : "Vapor",
"name" : "Vapor",
"name" : "mytunes-db"
"vm_name" : "OpenJDK 64-Bit Server VM",
"name" : "eth0",
"name" : "Timeslip",
"name" : "Timeslip",
"name" : "mytunes-db"
"vm_name" : "OpenJDK 64-Bit Server VM",
"name" : "eth0",
"name" : "Magik",
"name" : "Magik",
"name" : "mytunes-db"
"vm_name" : "OpenJDK 64-Bit Server VM",
"name" : "eth0",
"name" : "Brother Voodoo",
"name" : "Brother Voodoo",
"name" : "mytunes-db"
"vm_name" : "OpenJDK 64-Bit Server VM",
"name" : "eth0",
Documentation
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