Container Deployment and Management with kubernetes

Container Deployment and
Management
with kubernetes
1 July 2015
Loh Siu Yin
Technology Consultant, Beyond Broadcast LLP
1 of 27

Kubernetes
A system to manage docker containers across a cluster of hosts.
See: kubernetes.io(http://kubernetes.io)
and github.com/GoogleCloudPlatform/kubernetes(https://github.com/GoogleCloudPlatform/kubernetes)
2 of 27

Prerequisites
Docker (boot2docker, coreos, static binary)
Images (from hub.docker.com or build your own)
kubernetes
3 of 27

Build a base image
Dockerfile for gozmq: A standardized environment my golang and ZeroMQ programs
to run in.
# Dockerfile for gozmq
FROM ubuntu:14.04
ADD libzmq.so.1 /usr/lib/
CMD ["/bin/bash"]
Building the image:
#!/bin/sh
# image_build.sh
PGM='gozmq'
MAIN_VER=20150525
#MAIN_VER=`date +%Y%m%d`
SUB_VER=
VER=${MAIN_VER}${SUB_VER}
docker build -t siuyin/${PGM}:${VER} .
Check with: docker images | grep gozmq
6 of 27

Build application image: master-publisher
The publisher in a pub-sub system.
# Dockerfile for publisher
FROM siuyin/gozmq:20150525
ENV PULL_BIND_PORT='tcp://*:5123'
ENV PUB_BIND_PORT='tcp://*:5124'
ADD publisher /usr/bin/
CMD ["/usr/bin/publisher"]
#!/bin/sh
# image_build for publisher
PGM='publisher'
#MAIN_VER=`date +%Y%m%d`
MAIN_VER=20150525
SUB_VER=
VER=${MAIN_VER}${SUB_VER}
docker build -t siuyin/${PGM}:${VER} .
Check with: docker images | grep publisher
7 of 27

Publisher
Demo:
cd ~/prog/go_workspace/src/siuyin/zmqcomp/publisher (vim start.sh)
test_pusher, publisher then test_subscriber
8 of 27

Nice: Fully functional but limited to running on the docker host
Note: localhost and port configuration via environment variables.
#!/bin/sh
# test_pusher
# local docker host
#PUSH_CONNECT_HOST=localhost PUSH_CONNECT_PORT=5123 go run main.go
# kubernetes cluster network 1
#PUSH_CONNECT_HOST=172.17.0.17 PUSH_CONNECT_PORT=5123 go run main.go
PUSH_CONNECT_HOST=10.0.0.50 PUSH_CONNECT_PORT=5123 go run main.go
# kubernetes node local
Enter kubernetes
Brendan Burns of Google: "kubernetes -- ancient greek for pilot"
I am thinking: The Borg Cube: "resistance is futile ... you will be assimilated"
9 of 27

Kubernetes Survival Guide
12 of 27

Resources
pod:
One or more closely coupled docker containers
replication controller (or rc):
Actively manages pods
service (or svc):
A stable end-point to connect to running pods
node (previously minion):
A host that runs pods.
13 of 27

(Re)starting kubernetes
After a reboot, kubernetes containers from gcr.io/google ... will not be running.
Restart them with this script:
docker ps -a| grep gcr.io/google | awk '{print $1}'|xargs docker start
14 of 27

Kubernetes operations
get: retrieve summary status on a resource (pod, rc, svc, node)
describe: get more details on a resource (eg. describe svc master-publisher)
delete: deletes a resource
create: creates a resource
Demo: kubectl get nodes
kubernetes cluster api-controller runs on localhost:8080(http://localhost:8080)
Possible to curl to localhost:8080 with the api:
curl -L http://localhost:8080/api/v1beta3/nodes
or with GET requests on your browser localhost:8080/api/v1beta3/nodes(http://localhost:8080
/api/v1beta3/nodes)
15 of 27

Creating a ReplicationController which creates pods
Defined in a .json or .yaml file:
"containers": [{
"name": "publisher",
"image": "siuyin/publisher:20150525",
"imagePullPolicy": "IfNotPresent",
"env": [{
"name": "PULL_BIND_PORT",
"value": "5123"
},{
"name": "PUB_BIND_PORT",
"value": "5124"
}],
"ports": [{
"containerPort": 5123,
"protocol": "TCP"
},
{
"containerPort": 5124,
"protocol": "TCP"
}
]
}],
"restartPolicy": "Always",
"volumes": []
16 of 27

publisher-controller.json
view ~/prog/go_workspace/src/siuyin/zmqcomp/publisher/publisher-controller.json
17 of 27

Demo: Create a replication controller
Note: kubectl delete rc -l name=master-publisher before re-creating replication
controller.
Demo:
cd ~/prog/go_workspace/src/siuyin/zmqcomp/publisher
kubectl create -f publisher-controller.json
kubectl get rc
Same effect with: kubectl get replicationcontrollers
Online scaling:
kubectl scale --replicas=3 rc master-publisher
18 of 27

Where is the pod?
Demo:
kubectl get pods
or better
kubectl get pods -l 'name=master-publisher'
Same as: kubectl get pods --selector='name=master-publisher'
Note the IP Address of this pod.
19 of 27

Pod IP address
Double-check: docker ps | grep master-publisher
Also: docker inspect <container UUID> | grep IPAddress
But where is the IP address in the docker container?
The network configuration is held in the "pause" container.
Demo: master-publisher pod running in dedicated sub-net
cd ~/prog/go_workspace/src/siuyin/zmqcomp/publisher
copy pod IP address to clipboard
configure and start test_pusher
configure and start test_subscriber
20 of 27

Scenario: Container or Pod failure
Suppose bad code or hardware causes the docker container or pod to fail.
Can kubernetes heal the system?
Demo: kill the docker container
docker ps | grep master-publisher
docker kill <container UUID>
Demo: delete the pod
kubectl get pod -l name=master-publisher
kubectl delete pod <pod-name>
or similarly:
kubectl delete pod -l name=master-publisher
21 of 27

How to survive a pod failure
The failed pod was re-created by the replication controller:
kubectl get pod -l name=master-publisher
note the pod's IP address
cat ~/prog/go_workspace/src/siuyin/zmqcomp/publisher/test_pusher/start.sh
The IP address changed!
Kubernetes made no attempt to revive the failed pod. Instead it created a new one and
gave it a new IP address.
22 of 27

We need a stable IP address!
Enter: kubernetes service
"kind":"Service",
"apiVersion":"v1beta3",
"metadata":{
"name":"master-publisher",
"labels":{
"name":"master-publisher"
}
},
"spec":{
view ~/prog/go_workspace/src/siuyin/zmqcomp/publisher/publisher-service.json
Note the NodePort type and port declarations.
23 of 27

Inspecting the service
I've already created the service with (don't create it again):
kubectl create -f publisher-service.json
Check it with:
kubectl get service -l name=master-publisher
kubectl describe svc master-publisher
Demo: reconfigure to use service IP address:
reconfigure test_pusher
reconfigure test_subscriber
Demo: fail the pod again
kubectl delete pod -l name=master-publisher
24 of 27

Making the service accessible from outside the cluster
Specify a publicIP in the service declaration and use it:
#!/bin/sh
# test_pusher
# local docker host
#PUSH_CONNECT_HOST=172.17.0.17 PUSH_CONNECT_PORT=5123 go run main.go
PUSH_CONNECT_HOST=10.0.0.50 PUSH_CONNECT_PORT=5123 go run main.go
# kubernetes node local
To define your own port map, refer to NODEPORT entries in:
iptables -t nat -S
25 of 27

Slides Download
http://www.slideshare.net/siuyin/siuyin-dockerkubernetes
26 of 27

Thank you
Loh Siu Yin
Technology Consultant, Beyond Broadcast LLP
siuyin@beyondbroadcast.com(mailto:siuyin@beyondbroadcast.com)
27 of 27

Container Deployment and Management with kubernetes

More Related Content

What's hot (20)

Similar to Container Deployment and Management with kubernetes (20)

Recently uploaded (20)

Container Deployment and Management with kubernetes