Introduction to Docker & CoreOS - Symfony User Group Cologne
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This document provides an introduction and overview of Docker and CoreOS. It describes Docker as a tool for isolation processes in lightweight Linux containers and discusses CoreOS, a minimal Linux distribution focused on running modern infrastructure stacks. CoreOS utilizes Docker containers and tools like Etcd for service discovery, Locksmith for updates, Cloud Config for initialization, Flannel for networking, and Fleet for cluster management.
![Dockerfile
FROM ubuntu:14.04
RUN apt-get update &&
apt-get -y install redis-server
EXPOSE 6379
ENTRYPOINT ["/usr/bin/redis-server"]](https://image.slidesharecdn.com/dockercoreossymfonyusergroupcologne-141017043924-conversion-gate02/85/Introduction-to-Docker-CoreOS-Symfony-User-Group-Cologne-7-320.jpg)
![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"](https://image.slidesharecdn.com/dockercoreossymfonyusergroupcologne-141017043924-conversion-gate02/85/Introduction-to-Docker-CoreOS-Symfony-User-Group-Cologne-19-320.jpg)
![Unit file
[Unit]
Description=A Redis Server
[Service]
TimeoutStartSec=0
ExecStartPre=/usr/bin/docker pull denderello/redis
ExecStart=/usr/bin/docker run --rm -p 6379 --name %n
denderello/redis
ExecStop=/usr/bin/docker stop %n](https://image.slidesharecdn.com/dockercoreossymfonyusergroupcologne-141017043924-conversion-gate02/85/Introduction-to-Docker-CoreOS-Symfony-User-Group-Cologne-34-320.jpg)
Introduction to Docker & CoreOS - Symfony User Group Cologne
- 1. Introduction to Docker & CoreOS Dennis Benkert @denderello
- 2. Simple service orchestration, built for developers. Based in Cologne, Germany. Ten terrific folks, and hiring! http://giantswarm.io/
- 4. Docker ● Isolation of processes in linux containers ● Lightweight and fast ● Portable
- 5. Docker Technology ● Utilized LXC until version 0.9 ● Now uses libcontainer which e.g. supports systemd-nspawn, libvirt-lxc, BSD-Jails, etc. ● Copy-On-Write filesystem (e.g. AUFS or BTRFS) ● Written in Go
- 7. Dockerfile FROM ubuntu:14.04 RUN apt-get update && apt-get -y install redis-server EXPOSE 6379 ENTRYPOINT ["/usr/bin/redis-server"]
- 8. Running containers $ docker build -t denderello/redis . $ docker run -d --name redis -p 6379:6379 denderello/redis $ nc localhost 6379
- 10. 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.
- 11. Features ● Automatic Updates ● Docker Containers ● Cluster management ● Service Discovery
- 12. Linux Basis ● Based on Gentoo ● systemd ● btrfs ● Images for PXE, OpenStack, AWS, GCE, Vagrant
- 13. “Immutable” System ● Read-only rootfs ● Writeable overlay on /etc
- 14. No classic package manager ● ChromeOS inspired update engine ● Atomic Updates ● Rollbacks ● Using Docker to distribute software
- 15. CoreOS own tools ● Etcd ● Locksmith ● Cloud-config ● Flannel ● Fleet https://github.com/coreos
- 16. Etcd A highly-available key value store for shared configuration and service discovery.
- 17. Etcd ● Basis for > Configuration management > Service Discovery ● REST Interface ● Raft consensus algorithm http://raftconsensus.github.io/
- 18. Etcd Cluster
- 19. 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"
- 20. Locksmith Reboot manager for the CoreOS update engine.
- 21. Locksmith ● Reboot strategies for CoreOS updates ● Uses etcd for distributed locks ● Alpha, Beta, Stable channels
- 22. Cloud Config Customize a CoreOS machine through user-data.
- 23. Cloud Config ● Initialization of your instances ● Configure etcd, fleet, locksmith ● YAML file ● eg. EC2 user-data, Autoscaler launch-config
- 24. Configure your cluster #cloud-config coreos: update: reboot-strategy: etcd-lock
- 25. Configure your cluster #cloud-config coreos: update: reboot-strategy: etcd-lock etcd: discovery: https://discovery.etcd.io/<token>
- 26. Configure your cluster #cloud-config coreos: update: reboot-strategy: etcd-lock etcd: discovery: https://discovery.etcd.io/<token> users: - name: denderello ssh-authorized-keys: ...
- 27. Flannel Overlay networks backed by etcd.
- 28. Cloud overlay network ● One subnet per machine ● Get rid of docker port mapping ● Let containers talk to each other via IP addresses
- 29. Backends ● Encapsulate packets in UDP ● VXLAN implementation coming
- 30. Fleet Systemd for the cluster
- 31. Fleet ● CLI and API to start your containers ● Uses etcd and systemd
- 32. Fleet deployment
- 33. Fleet Scheduler ● Relatively simple > By meta data > Same machine/exclusion ● Resolve service dependencies! ● More to come > Resource management (CPU, memory etc.)
- 34. Unit file [Unit] Description=A Redis Server [Service] TimeoutStartSec=0 ExecStartPre=/usr/bin/docker pull denderello/redis ExecStart=/usr/bin/docker run --rm -p 6379 --name %n denderello/redis ExecStop=/usr/bin/docker stop %n
- 35. 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
- 37. Three-Tier Application ● Load Balancer ● App ● Database
- 38. Sidekick Keep configuration out of your app
- 39. Ambassador Reverse proxy for your service Keep service discovery out of your app
- 40. Using CoreOS
- 41. Thanks for listening! Reach out: Dennis Benkert @denderello @giantswarm