change kubernetes examples to use Deployment

[rongou]

What do these changes do?

Change the kubernetes examples to use Deployment as this is now recommended over ReplicationControllers.

Also reduce the CPU requirements to make it easier to try this out on a development environment (kubeadm, MicroK8s etc.).

[robertnishihara]

@rongou thanks a lot for the fixes! I'll try it out.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/11320/
Test PASSed.

[robertnishihara]

Thanks a lot @rongou! This seems to work for me. Note that I had to make a small change to the example.

We start a redis server on the head node. Then we try to connect to it by doing

import redis
import socket

redis.StrictRedis(host=socket.gethostbyname("ray-head"), port=6379)

socket.gethostbyname("ray-head") returns something like 10.104.7.64, whereas the "correct" IP address seems to be something more like 172.17.0.6.

The attempt to connect to Redis succeeds when done from a node other than the one that Redis is on, but it fails when done from the same node that Redis is on. That's why I switched to using localhost in the example when we are on the same machine that the Redis servers are on.

Later on it may make sense to simply start all of the Redis servers on a different collection of nodes.

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/11337/
Test FAILed.