Introction to docker swarm

1. Introduction to Docker Swarm
Hsi-Kai Wang

2. Outline
• Docker Cluster
• Swarm
• Swarm + Consul + overlay network

3. What is PC Cluster
• A computer cluster consists of a set of
loosely or tightly connected computers that
work together so that, in many respects,
they can be viewed as a single system.
Unlike grid computers, computer clusters
have each node set to perform the same
task, controlled and scheduled by
software.
Ref: Computer cluster wiki

4. Docker Cluster Software
• Apchae Mesos
– abstract resource
• docker swarm
– easy way to cluster
– standard Docker API
• kubernetes
– container merge
– sample scaling

5. What is Swarm
• Docker Swarm is native clustering for
Docker. It turns a pool of Docker hosts
into a single, virtual Docker host. Because
Docker Swarm serves the standard
Docker API, any tool that already
communicates with a Docker daemon can
use Swarm to transparently scale to
multiple hosts.

6. Software Environment
• OS
– CentOS: 7 (7.1.1503)
• Software
– Docker 1.10 (1.10.3.cs2)
– Docker container network (Docker >= 1.9)
– Swarm (Docker >= 1.5, 2375 port)
– Consul

7. Swarm cluster
Docker
Host
172.17.33.83
Docker
Host
172.17.33.84
Docker
Host
swarmswarmswarm
Docker
Host
swarm
172.17.33.86
swarm cluster
swarm manager
swarm node

8. Docker - Setting• # docker install (Commercially Support, CS)
centos:~ # rpm --import https://sks-
keyservers.net/pks/lookup?op=get&search=0xee6d536cf7dc86e2d7d5
6f59a178ac6c6238f52e
centos:~ # yum install yum-utils
centos:~ # yum-config-manager --add-repo
https://packages.docker.com/1.10/yum/repo/main/centos/7
centos:~ # yum install docker-engine
centos:~ # systemctl enable docker.service
centos:~ # systemctl start docker.service
centos:~ # docker version # check version >= 1.5
• # docker config
centos:~ # vi /etc/systemd/system/multi-
user.target.wants/docker.serivce
...
ExecStart=/usr/bin/docker daemon -H tcp://0.0.0.0:2375 -H
unix:///var/run/docker.sock
...
centos:~ # systemctl restart docker.service
centos:~ # docker pull swarm
update setting

9. Swarm - config
• # run once to get swarm token_id
centos:~ # docker run --rm swarm create
c4602d1cf638ac9805a0693499f04404
• # setup swarm node
node:~ # docker run -d swarm join --
advertise=172.17.33.83:2375
token://c4602d1cf638ac9805a0693499f04404
• # setup swarm manager
manager:~ # docker run -d -p 2375:2375 swarm manage
token://c4602d1cf638ac9805a0693499f04404
• # list swarm cluster
manager/node:~ # docker run --rm swarm list
token://c4602d1cf638ac9805a0693499f04404
swarm node IP
token id

10. Swarm - usage
• # usage 1
manager:~ # docker -H 172.17.33.86:2375 info
manager:~ # docker -H 172.17.33.86:2375 run hello-world
manager:~ # docker -H 172.17.33.86:2375 ps -a
• # usage 2
manager:~ # export DOCKER_HOST=172.17.33.86:2375
manager:~ # docker info
manager:~ # docker run hello-world
manager:~ # unset DOCKER_HOST
swarm manager IP
swarm manager IP

11. Key/Value Server for Docker
• Apache ZooKeeper
• Consul
• etcd

12. What is Consul
• Consul has multiple components, but as a
whole, it is a tool for discovering and
configuring services in your infrastructure.
It provides several key features:
– Service Discovery
– Key/Value Store
– Multi Datacenter
– Health Checking

13. Docker container network
• Default Networks
– bridge
– none
– host
• User-Defined Networks
– bridge
– overlay

14. Default Networks
Container
eth0
Host
eth0
docker0
vethxx
Container
eth0
Container
eth0
bridge network none network host network

15. User-Defined Networks
Container
eth0
Host
docker_gwbridge
vethxx
eth1
eth0
Container
eth1
Host
docker_gwbridge
vethxx
eth0
eth0
overlay network

16. Swarm cluster + Consul + overlay network
Docker
Host
172.17.33.83
Docker
Host
172.17.33.84
Docker
Host
swarmswarmswarm
Docker
Host
swarm
172.17.33.86
swarm cluster
swarm manager
swarm node
consul

17. Consul
• # consul install
consul:~ # docker pull progrium/consul
consul:~ # docker run -d -p 8500:8500 progrium/consul -server -
bootstrap
• # consul test
consul:~ # curl -L http://172.17.33.86:8500/v1/catalog/nodes
consul IP

18. Docker - Setting
• # docker install (Commercially Support, CS)
centos:~ # rpm --import https://sks-
keyservers.net/pks/lookup?op=get&search=0xee6d536cf7dc86e2d7d5
6f59a178ac6c6238f52e
centos:~ # yum install yum-utils
centos:~ # yum-config-manager --add-repo
https://packages.docker.com/1.10/yum/repo/main/centos/7
centos:~ # yum install docker-engine
centos:~ # systemctl enable docker.service
centos:~ # systemctl start docker.service
centos:~ # docker version # check version >= 1.9
• # docker config
centos:~ # vi /etc/systemd/system/multi-
user.target.wants/docker.serivce
...
ExecStart=/usr/bin/docker daemon -H tcp://0.0.0.0:2375 -H
unix:///var/run/docker.sock
--cluster-store=consul://172.17.33.86:8500 --cluster-
advertise=172.17.33.83:2375
...
centos:~ # systemctl restart docker.service
centos:~ # docker pull swarm
consul IP
swarm node IP

19. Swarm
• # setup swarm node
node:~ # docker run -d swarm join --advertise=172.17.33.83:2375
consul://172.17.33.86:8500/dc1
• # setup swarm manager
manager:~ # docker run -d -p 2376:2375 swarm manage
consul://172.17.33.86:8500/dc1
• # list swarm cluster
manager:~ # docker run --rm swarm list
consul://172.17.33.86:8500/dc1
swarm node IPconsul IP

20. overlay network
• manager:~ # docker network create -d overlay onetwork
manager:~ # docker network ls
• manager:~ # docker run -itd --name=abc --
env="constraint:node==d1" --net=onetwork ubuntu /bin/bash
manager:~ # docker run -itd --name=xyz --
env="constraint:node==d2" --net=onetwork ubuntu /bin/bash
manager:~ # docker ps
--subnet=10.0.9.0/24
--ip-range=10.0.9.0/24

21. overlay network
• manager:~ # docker network inspect onetwork
manager:~ # docker exec -it abc ping -c3 10.0.0.3

22. Reference
• Manually Install the CS Docker Engine
• Understand Docker container networks
• 深入瞭解 Docker Container Networks
• 用Docker Swarm打造多主機叢集環境
• Docker cluster with swarm, consul,
registrator and consul-template