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Last pushed: 3 months ago
Short Description
Kubernetes Redis with High Availability that just works
Full Description

Kubernetes Redis with High Availability

Redis Images and Samples in this project are implemented using the latest features of Kubernetes:

  • StatefulSet
  • Init Container

Requirements

  • Kubernetes 1.6 cluster
  • Redis 3.2

Quick Start

If you already have a Kubernetes cluster, you can deploy High Availability Redis using the following command:

$ kubectl create -f example/
service "redis-sentinel" created
statefulset "redis-sentinel" created
service "redis-server" created
statefulset "redis-server" created
pod "console" created

Accessing Redis

You can access Redis server using console pod:

$ kubectl exec -ti console -- /bin/bash
root@console:# export MASTER_IP="$(redis-cli -h redis-sentinel -p 26379 sentinel get-master-addr-by-name mymaster | head -1)"
root@console:# export SERVER_PASS="_redis-server._tcp.redis-server.default.svc.cluster.local"
root@console:# redis-cli -h "${MASTER_IP}" -a "${SERVER_PASS}" set foo bar
OK
root@console:# redis-cli -h redis-server -a "${SERVER_PASS}" get foo
bar

The passowrd is necessary for preventing independent Redis clusters from merging together in some circumstances.

Scale Up and Down

With tarosky/k8s-redis-ha, you can scale up/down Redis servers and Redis sentinels like the normal Deployment resources:

$ kubectl scale --replicas=5 statefulset/redis-sentinel
statefulset "redis-sentinel" scaled
$ kubectl scale --replicas=5 statefulset/redis-server
statefulset "redis-server" scaled

After these scale up/down, the expected number of available slaves in the Redis set are reset automatically.

Sample Code in Python

$ kubectl exec -ti console -- ipython
In [1]: from redis import StrictRedis

In [2]: from redis.sentinel import Sentinel

In [3]: sentinel = Sentinel([
   ...:         ('redis-sentinel-0.redis-sentinel.default.svc.cluster.local', 26379),
   ...:         ('redis-sentinel-1.redis-sentinel.default.svc.cluster.local', 26379),
   ...:         ('redis-sentinel-2.redis-sentinel.default.svc.cluster.local', 26379)
   ...:     ], socket_timeout=0.1
   ...: )

In [4]: master = sentinel.master_for(
   ...:     'mymaster',
   ...:     password='_redis-server._tcp.redis-server.default.svc.cluster.local',
   ...:     socket_timeout=0.1
   ...: )

In [5]: slave = sentinel.slave_for(
   ...:     'mymaster',
   ...:     password='_redis-server._tcp.redis-server.default.svc.cluster.local',
   ...:     socket_timeout=0.1
   ...: )

In [6]: master.set('foo', 'bar')
Out[6]: True

In [7]: slave.get('foo')
Out[7]: b'bar'

Running the Test Script

$ pyvenv .venv
$ source .venv/bin/activate
$ pip install -r test/requirements.txt

You can run the test command using the following command:

$ KUBE_NAMESPACE='{{Your name space}}' nosetests test/test.py
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