Presentation on Docker Networking from Aditya Gawade at the Boulder Linux User's Group MeetUp on 12/8/2016.

1. Docker Networking
ADITYA GAWADE

2. Docker Basics
MANAGING IMAGES AND CONTAINERS

3. What's Docker?
 Containerization platform
 Provides leaner / application specific virtual machines.
 Uses existing kernel features such as namespaces and cgroups
 Open source and available on Linux distributions.
 Applications are installed on containers packaged, shipped and deployed
 This eliminates low level dependencies.

4. How Docker Works?
Host
Client
Registry
Docker-client
Docker run
Docker ps
C1
C2
C3
Docker daemon
N
E
T
W
O
R
K

5. Docker basic commands
 Docker run – Run a container
 Docker attach – attach to a running container
 Docker info – identify docker version and configuration details
 Docker ps – Show currently running containers.
 Docker images - list images cached locally.
 Docker <command> --help – show command options

6. Docker Single Host
Networking
NETWORK ON A SINGLE DOCKER HOST

7. Docker Bridge
 Docker provides a default bridge "docker0"
 By default, all containers are connected to "docker0"
 Bridge connects all containers on a single host
 Docker network ls – to view existing networks

8. User defined Networks (Bridge)
 Docker network create – to create a new network/driver
 Docker run –itd –name=container1 –network=<custom bridge name> <image>
 Eg:
docker network create –driver bridge isolated_nw
Option to
create a
network
Create
custom driver
Custom network
name

9. Multi-host Networking
(Overlay)
DEPLOYING A NETWORK ACROSS HOSTS

10. Different Methods of Multihost
Networking
 Overlay Network
 Macvlan
 Open virtual switch (OVS)
 Standard bridge utilites (brctl)

11. Overlay Concept
KV STORE
Consul
Docker Host 1 Docker Host 2
C1 C2Serf + VXLAN
Overlay Network

12. Serf
 Created by Hashicorp
 Used for orchestration and cluster management
 Uses Gossip Protocol
 Infrequent UDP messages
 Supported on Linux, Mac OS and Windows

13. VXLAN (Virtual Extensible LAN)
 Extend VLAN address space.
 Used for Overlays to implement Encapsulation over Layer 3 infrastructure
 Encapsulates Layer 2 information (VXLAN No.) in Layer 3 Packet.
Image sourced from "Arista VXLAN Bridging with DCI Head End Replication"
http://www.intelligentvisibility.com/blog/?p=376

14. Steps to create an overlay network
1. Check and update Docker Engine (Latest version 1.12) on hosts.
2. Set up a KV Store
3. Connect hosts to KV store
4. Create an overlay network.
5. Add containers to overlay network
6. Check connectivity between containers

15. Setting up a KV store
 We are using a Consul container as a Docker host
 It s deployed on an external host.
 docker run -d -p 8500:8500 -h consul --name consul progrium/consul -server -bootstrap
-p = publish a container's port to host
-d = detach/ run in background
-h = container hostname
 Docker port consul – check port binding

16. Connecting hosts to KV Store
 Stop the docker service
$ sudo systemctl stop docker.service (RedHat)
$ sudo service docker stop
 Connect hosts to KV store
sudo docker daemon -H tcp://0.0.0.0:2375 -H unix://var/run/docker.sock --
cluster-advertise <Net int of host>:2375 --cluster-store consul://<Public IP of host
interface>:8500
-H = host --cluster-advertise = send advertisements for cluster on intf:2375 --
cluster-store = IP of KV store/cluster manager

17. Hosts Joining a Cluster

18. Create an overlay Network
 On any host:
docker network create –d overlay --subnet=<IP address>/<Mask> <network
name>

19. Add containers to overlay network
 On each of the hosts:
docker run –itd --name=<container name> --network=<overlay name>
<container image>
Docker network inspect <overlay name> (for Verification)

20. Overlay Network Image

21. Checking connectivity between containers
 Ping From C1 to C2
docker exec C2 ping –w5 C1

22. References
 Introduction to Docker:
https://sysadmincasts.com/episodes/31-introduction-to-docker
 Docker Container Networking:
https://docs.docker.com/engine/userguide/networking/
 Docker Multi-host Network:
https://luppeng.wordpress.com/2016/05/03/setting-up-an-overlay-network-on-docker-without-swarm/
 Docker Networking Deep Dive (DockerCon 15):
https://www.youtube.com/watch?v=vb7U_9AO7Ww
 4 Ways to Connect Containers to Local Network
http://blog.oddbit.com/2014/08/11/four-ways-to-connect-a-docker/
 VXLAN Definition:
http://whatis.techtarget.com/definition/VXLAN
 Serf
https://www.serf.io/
 Install Docker on Ubuntu
https://docs.docker.com/engine/installation/linux/ubuntulinux/
 Install Docker on Centos
https://docs.docker.com/engine/installation/linux/centos/