examples/rethinkdb

RethinkDB Cluster on Kubernetes

Setting up a rethinkdb cluster on kubernetes

Features

• Auto configuration cluster by querying info from k8s
• Simple

Quick start

Step 1

antmanler/rethinkdb will discover peer using endpoints provided by kubernetes_ro service, so first create a service so the following pod can query its endpoint

kubectl create -f driver-service.yaml

check out:

$kubectl get se
NAME                LABELS              SELECTOR                  IP                  PORT
rethinkdb-driver    db=influxdb         db=rethinkdb              10.241.105.47       28015

Step 2

start fist server in cluster

kubectl create -f rc.yaml

Actually, you can start servers as many as you want at one time, just modify the replicas in rc.ymal

check out again:

$kubectl get po
POD                                    IP                  CONTAINER(S)        IMAGE(S)            HOST                LABELS                       STATUS
99f6d361-abd6-11e4-a1ea-001c426dbc28   10.240.2.68         rethinkdb           rethinkdb:1.16.0    10.245.2.2/         db=rethinkdb,role=replicas   Running

Done!

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Scale

You can scale up you cluster using kubectl resize, and new pod will join to exsits cluster automatically, for example

$kubectl resize rc rethinkdb-rc-1.16.0 --replicas=3
resized
$kubectl get po
POD                                    IP                  CONTAINER(S)        IMAGE(S)            HOST                LABELS                       STATUS
99f6d361-abd6-11e4-a1ea-001c426dbc28   10.240.2.68         rethinkdb           rethinkdb:1.16.0    10.245.2.2/         db=rethinkdb,role=replicas   Running
d10182b5-abd6-11e4-a1ea-001c426dbc28   10.240.26.14        rethinkdb           rethinkdb:1.16.0    10.245.2.4/         db=rethinkdb,role=replicas   Running
d101c1a4-abd6-11e4-a1ea-001c426dbc28   10.240.11.14        rethinkdb           rethinkdb:1.16.0    10.245.2.3/         db=rethinkdb,role=replicas   Running

Admin

You need a separate pod (which labled as role:admin) to access Web Admin UI

kubectl create -f admin-pod.yaml
kubectl create -f admin-service.yaml

find the service

$kubectl get se
NAME                LABELS              SELECTOR                  IP                  PORT
rethinkdb-admin     db=influxdb         db=rethinkdb,role=admin   10.241.220.209      8080
rethinkdb-driver    db=influxdb         db=rethinkdb              10.241.105.47       28015

open a web browser and access to http://10.241.220.209:8080 to manage you cluster

Why not just using pods in replicas?

This is because kube-proxy will act as a load balancer and send your traffic to different server, since the ui is not stateless when playing with Web Admin UI will cause Connection not open on server error.

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BTW

• All services and pods are placed under namespace rethinkdb.

• gen_pod.sh is using to generate pod templates for my local cluster, the generated pods which is using nodeSelector to force k8s to schedule containers to my designate nodes, for I need to access persistent data on my host dirs.

• see antmanler/rethinkdb-k8s for detail