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.
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
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
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
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)
