Introduction to CoreOS

1. Introduction to
CoreOS
Timo Derstappen
@teemow

2. Simple service orchestration,
built for developers.
Based in Cologne, Germany.
Ten terrific folks, and hiring!
http://giantswarm.io/

3. What is CoreOS?

4. Minimal Linux
CoreOS enables warehouse-scale computing
on top of a minimal, modern operating
system.
A new Linux Distribution to provide features
needed to run modern infrastructure stacks.

5. Features
● Automatic Updates
● Docker Containers
● Cluster management
● Service Discovery

6. Linux Basis
● Based on Gentoo
● systemd
● btrfs
● Images for PXE,
OpenStack, AWS,
GCE, Vagrant

7. “Immutable” System
● Read-only rootfs
● Writeable overlay on /etc

8. No classic package manager
● ChromeOS inspired update engine
● Atomic Updates
● Rollbacks
● Using Docker to distribute software

9. CoreOS own tools
● Etcd
● Locksmith
● Cloud-config
● Flannel
● Fleet
https://github.com/coreos

10. Etcd
A highly-available key value store for shared
configuration and service discovery.

11. Etcd
● Basis for
> Configuration management
> Service Discovery
● REST Interface
● Raft consensus algorithm
http://raftconsensus.github.io/

12. Etcd Cluster

13. Discovery API
$> curl https://discovery.etcd.io/new
https://discovery.etcd.
io/463c1435f9f63c952e0899b1f459c0fe
$> curl -s https://discovery.etcd.
io/463c1435f9f63c952e0899b1f459c0fe | jq ".node.
nodes[].value"
"http://172.31.19.1:7001"
"http://172.31.19.0:7001"
"http://172.31.18.255:7001"

14. Locksmith
Reboot manager for the CoreOS update
engine.

15. Locksmith
● Reboot strategies for CoreOS updates
● Uses etcd for distributed locks
● Alpha, Beta, Stable channels

16. Cloud Config
Customize a CoreOS machine through user-data.

17. Cloud Config
● Initialization of your instances
● Configure etcd, fleet, locksmith
● YAML file
● eg. EC2 user-data, Autoscaler launch-config

18. Configure your cluster
#cloud-config
coreos:
update:
reboot-strategy: etcd-lock

19. Configure your cluster
#cloud-config
coreos:
update:
reboot-strategy: etcd-lock
etcd:
discovery: https://discovery.etcd.io/<token>

20. Configure your cluster
#cloud-config
coreos:
update:
reboot-strategy: etcd-lock
etcd:
discovery: https://discovery.etcd.io/<token>
users:
- name: teemow
coreos-ssh-import-github: teemow

21. Flannel
Overlay networks backed by etcd.

22. Cloud overlay network
● One subnet per machine
● Get rid of docker port mapping
● Let containers talk to each other via IP
addresses

23. Backends
● Encapsulate packets in UDP
● VXLAN implementation coming

24. Fleet
Systemd for the cluster

25. Fleet
● CLI and API to start your containers
● Uses etcd and systemd

26. Fleet deployment

27. Fleet Scheduler
● Relatively simple
> By meta data
> Same machine/exclusion
● Resolve service dependencies!
● More to come
> Resource management (CPU, memory etc.)

28. Unit file
[Unit]
Description=A Redis Server
[Service]
TimeoutStartSec=0
ExecStartPre=/usr/bin/docker pull teemow/redis
ExecStart=/usr/bin/docker run --rm -p 6379 --name %n
teemow/redis
ExecStop=/usr/bin/docker stop %n

29. Manage a service
$> fleetctl start redis.service
$> fleetctl list-units
$> fleetctl status redis.service
$> fleetctl journal redis.service
$> fleetctl stop redis.service
$> fleetctl destroy redis.service

30. Service Discovery

31. Three-Tier Application
● Load Balancer
● App
● Database

32. Sidekick
Keep
configuration out
of your app

33. Ambassador
Reverse proxy for
your service
Keep service
discovery
out of your app

34. Using CoreOS

35. CoreOS
● Great foundation to create flexible
distributed infrastructures
● Unix philosophy

36. Kubernetes
● Google
Container
Orchestration
● Runs on top of
CoreOS

37. cAdvisor
● Monitoring for your
containers
● Collects,
aggregates and
processes metrics
● InfluxDB Backend
● Monitoring of
clusters with
Heapster

38. Deis
Heroku-like Open
Source PaaS

39. Panamax
● Web interface to start multi container apps
● App Templates on Github
● Open Source project from CenturyLink
Labs

40. We ♥ CoreOS

41. There is a Meetup in Cologne
Docker Cologne - CoreOS Meetup
19:00, 14th October
Startplatz
Brandon Philips, CTO of CoreOS
Luke Marsden, CTO of Flocker

42. Sign up for the
Giant Swarm private Beta
Request Invite
http://giantswarm.io/

43. Thanks for listening!
Reach out:
Timo Derstappen
@teemow
@giantswarm