This document introduces CoreOS, an open source operating system focused on automation, security, and scalability. It provides automatic updates, uses Docker containers, and includes tools like Etcd for service discovery and configuration. CoreOS is based on Gentoo Linux and uses systemd. It focuses on immutable infrastructure with atomic updates and rollbacks. The document describes CoreOS tools like Etcd, Locksmith, Cloud Config, Flannel and Fleet for cluster management.

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