Swarm allows multiple Docker hosts to be clustered together into a single virtual Docker host. It provides features like scheduling, rescheduling on failure, high availability with multiple masters, and service discovery. To set up a Swarm cluster, run the Swarm manager container on one host and restart the Docker daemons on the other hosts with arguments to join the cluster. An example voting app microservices demo shows how to deploy an application across a Swarm cluster.

1. Swarm: Docker Native Clustering
Mike Goelzer
mgoelzer@docker.com
GH: @mgoelzer
Freenode/Twitter: @mikegoelzer

2. Swarm: Simplicity, Flexibility, Ease of Setup
• What is Swarm?
• How do you set it up?
• Sample microservice application on Swarm

3. Swarm turns multiple Docker hosts into a
single, virtual Docker host.

4. docker daemon
(node-1)
Container
Container
>_
Docker CLI
docker
Docker Compose
Kitematic
Jenkins plugin

5. docker daemon
(node-1)
Container
Container
>_
Docker CLI
Swarm manager
docker
Docker Compose
Kitematic
Jenkins plugin
docker daemon
(node-0)
Container
Container
docker daemon
(node-2)
Container
Container

6. Swarm Features
• Scheduling
• Rescheduling on failure
• HA (multiple masters)
• Labels, affinities and constraints to control scheduling decisions
• DNS-based service discovery

7. Simple: 2 steps to create a cluster
1. Run Swarm Manager
2. Restart your Docker daemons with
some extra arguments

8. Step 1: Start Swarm manager
docker run -d -p 3375:2375 swarm manage consul://192.168.33.10:8500/
Refs:
https://docs.docker.com/swarm
https://docs.docker.com/swarm/install-manual/

9. Step 2: Add some args to your daemons
Restart Docker daemons with:
DOCKER_OPTS=
-H=tcp://0.0.0.0:2375
--cluster-store=consul://192.168.33.11:8500
--cluster-advertise=eth1:2375
Refs:
https://docs.docker.com/swarm
https://docs.docker.com/swarm/install-manual/

10. Voilà, a cluster

11. Example Repo: Microservice App on Swarm
Upcoming Swarm Meetup:
http://www.meetup.com/Docker-Mountain-View/events/228284089/
https://github.com/mgoelzer/swarm-demo-voting-app
Demonstrates a microservice app on Swarm including:
• Vagrantfile and AWS Cloud Formation template to deploy the cluster
• Load balanced web front end
• DNS-based service discovery

12. Interlock (nginx or ha_proxy)
web01
redis01
web02
redis02
web03
redis03
web04
redis04
web05
redis05
pg results-app
10.0.0.4
10.0.0.3
36.36.36.36
10.0.0.100
10.0.0.5
10.0.0.5
10.0.0.7
10.0.0.6
10.0.0.9
10.0.0.8
10.0.0.11
10.0.0.10
10.0.0.101
https://github.com/mgoelzer/swarm-demo-voting-app

13. Clustered Voting App
https://github.com/mgoelzer/swarm-demo-voting-app

14. Jérôme’s Example: Coin Miner
Slides: http://view.dckr.info/
Repo: https://github.com/jpetazzo/orchestration-workshop
Demonstrates:
• How to do batch workloads on Swarm
• ELK stack for logging and metrics
• Other load balancing patterns beyond Interlock

15. Mike Goelzer | mgoelzer@docker.com | GH: @mgoelzer | @mikegoelzer