This repo will explain you how to deploy a basic python application into kubernetes and how to rolling update it.
First thing first, you will need to build your application, for the sake of simplicity we are going to to build the application twice here (one for each version):
docker build -t agonzalezro/k8s-py-example .
The above command is going to create a docker image of your python application
living into src/. We will tag it as version 0.1:
docker tag agonzalezro/k8s-py-example:latest agonzalezro/k8s-py-example:0.1
You could have use the layer id as well, but this one is more straigh forward.
Now do some changes on src/app.py to differentiate both apps. When you are
done, build and tag your "new" app:
docker build -t agonzalezro/k8s-py-example .
docker tag agonzalezro/k8s-py-example:latest agonzalezro/k8s/py-example:0.2
When you are done push them to the hub, remember to create the project before hand:
docker push agonzalezro/k8s-py-example
Ok, now we are ready to deploy it into kubernetes. There are three important files in this repo:
- rc-0.1.yml: the replication controller for the first version.
- rc-0.2.yml: the replication controller for the second version.
- service.yml: the service for both.
Let's create a RC and a service for the first version:
kubectl -f rc-0.1.yml -f service.yml --validate=false
# The validate tag is just needed because of a bug in current k8s
Now if you do:
kubectl get services
You should be seeing something like this:
flaskapp-service 10.91.246.233 104.197.30.229 80/TCP name=web 1m
The second IP is your external IP for the version 1 of your app. You can visit it and you will see your awesome app running!
We have the version 0.1 running, I always want to run last versions of everything so I will update it:
kubectl rolling-update flaskapp-rc -f rc-0.2.yml
BOOM! Your app was gracefully deployed to the new version.
kubectl config view
kubectl cluster-info # Check that UI, it's pretty cool!
I did this small tutorial in part based on @ipedrazas work. You should read it as well!