How to build simple distributed and scalable application using Core OS stack.

1. Core OS
Lukáš Vyhlídka
HPE - Service Virtualization
lukas.vyhlidka@hpe.com

2. Have You Met Rick?
Rick is a Junior Dev-Ops guy
at the Awesome Soft Ltd.
He is a part of a team that has been given
a task to build and deploy a scalable web
application.

3. Scalable Application
Oh, looks
complicated.

4. Docker
Just the recapitulation

5. Docker
Virtual Machines Docker

6. Using the Docker
So far so good,
but what next?

7. Difficulties with the Docker
Hard to do
using just Docker

8. Networking with the Docker
Network
Docker Host
eth0
docker0
Container 1 eth0 veth7eb
veth18fContainer 2 eth0
Container 3 eth0 veth18f

9. Networking with the Docker
Network
Docker Host
eth0
docker0
Container 1 eth0 veth7eb
veth18fContainer 2 eth0
Container 3 eth0 veth18f
public IP
private IP

10. Difficulties with the Docker
I have to connect
by ssh to each
node...

11. Core OS
Let’s the fun begin

12. Core OS
▷ lightweight OS based on Linux Kernel
▷ designed to operate in cluster
▷ readonly OS partition
▷ cloud-config file initialization
▷ runs apps in Containers
▷ building blocks
○ docker (rkt in older releases)
○ etcd
○ fleet
○ flannel
What a promising
technology...

13. Core OS - docker
▷ platform to build, ship and run
distributed applications
▷ each app runs inside of a Container Right, got it...

14. Core OS - etcd
▷ distributed and consistent key/value store
▷ each Core OS host runs an instance
▷ stores the information about the Core OS cluster
○ service discovery
○ service keepalive
○ Core OS itself uses it to update the cluster
○ ...
leader
follower follower
Raft

15. Back to our Dockerized App

16. Core OS + etcd
Great, Web App
Backends can
discover itself...

17. Core OS - fleet
▷ distributed init system
○ low level
○ foundation for higher order orchestration
▷ uses systemd and etcd
▷ works with enhanced systemd unit files

18. Core OS + etcd

19. CoreOS + etcd + fleet
Fleet distributes
my app across
the cluster...

20. Core OS - flannel
▷ virtual network
▷ uses etcd
▷ gives subnet to
each host

21. CoreOS + etcd + fleet

22. Full Core OS stack
Looks like I’m
done!!!

23. We’re done
Last chance for questions
See you next time,
guys.