# Overlay Driver ### Design TODO ### Multi-Host Overlay Driver Quick Start This example is to provision two Docker Hosts with the **experimental** Libnetwork overlay network driver. ### Pre-Requisites - Kernel >= 3.16 - Experimental Docker client ### Install Docker Experimental Follow Docker experimental installation instructions at: [https://github.com/docker/docker/tree/master/experimental](https://github.com/docker/docker/tree/master/experimental) To ensure you are running the experimental Docker branch, check the version and look for the experimental tag: ``` $ docker -v Docker version 1.8.0-dev, build f39b9a0, experimental ``` ### Install and Bootstrap K/V Store Multi-host networking uses a pluggable Key-Value store backend to distribute states using `libkv`. `libkv` supports multiple pluggable backends such as `consul`, `etcd` & `zookeeper` (more to come). In this example we will use `consul` Install: ``` $ curl -OL https://dl.bintray.com/mitchellh/consul/0.5.2_linux_amd64.zip $ unzip 0.5.2_linux_amd64.zip $ mv consul /usr/local/bin/ ``` **host-1** Start Consul as a server in bootstrap mode: ``` $ consul agent -server -bootstrap -data-dir /tmp/consul -bind= ``` **host-2** Start the Consul agent: ``` $ consul agent -data-dir /tmp/consul -bind= $ consul join ``` ### Start the Docker Daemon with the Network Driver Daemon Flags **host-1** Docker daemon: ``` $ docker -d --kv-store=consul:localhost:8500 --label=com.docker.network.driver.overlay.bind_interface=eth0 ``` **host-2** Start the Docker Daemon with the neighbor ID configuration: ``` $ docker -d --kv-store=consul:localhost:8500 --label=com.docker.network.driver.overlay.bind_interface=eth0 --label=com.docker.network.driver.overlay.neighbor_ip= ``` ### QuickStart Containers Attached to a Network **host-1** Start a container that publishes a service svc1 in the network dev that is managed by overlay driver. ``` $ docker run -i -t --publish-service=svc1.dev.overlay debian root@21578ff721a9:/# ip add show eth0 34: eth0: mtu 1500 qdisc noqueue state UP group default link/ether 02:42:ec:41:35:bf brd ff:ff:ff:ff:ff:ff inet 172.21.0.16/16 scope global eth0 valid_lft forever preferred_lft forever inet6 fe80::42:ecff:fe41:35bf/64 scope link valid_lft forever preferred_lft forever ``` **host-2** Start a container that publishes a service svc2 in the network dev that is managed by overlay driver. ``` $ docker run -i -t --publish-service=svc2.dev.overlay debian root@d217828eb876:/# ping svc1 PING svc1 (172.21.0.16): 56 data bytes 64 bytes from 172.21.0.16: icmp_seq=0 ttl=64 time=0.706 ms 64 bytes from 172.21.0.16: icmp_seq=1 ttl=64 time=0.687 ms 64 bytes from 172.21.0.16: icmp_seq=2 ttl=64 time=0.841 ms ``` ### Detailed Setup You can also setup networks and services and then attach a running container to them. **host-1**: ``` docker network create -d overlay prod docker network ls docker network info prod docker service publish db1.prod cid=$(docker run -itd -p 8000:8000 ubuntu) docker service attach $cid db1.prod ``` **host-2**: ``` docker network ls docker network info prod docker service publish db2.prod cid=$(docker run -itd -p 8000:8000 ubuntu) docker service attach $cid db2.prod ``` Once a container is started, a container on `host-1` and `host-2` both containers should be able to ping one another via IP, service name, \.\ View information about the networks and services using `ls` and `info` subcommands like so: ``` $ docker service ls SERVICE ID NAME NETWORK CONTAINER 0771deb5f84b db2 prod 0e54a527f22c aea23b224acf db1 prod 4b0a309ca311 $ docker network info prod Network Id: 5ac68be2518959b48ad102e9ec3d8f42fb2ec72056aa9592eb5abd0252203012 Name: prod Type: overlay $ docker service info db1.prod Service Id: aea23b224acfd2da9b893870e0d632499188a1a4b3881515ba042928a9d3f465 Name: db1 Network: prod ``` To detach and unpublish a service: ``` $ docker service detach $cid . $ docker service unpublish . # Example: $ docker service detach $cid db2.prod $ docker service unpublish db2.prod ``` To reiterate, this is experimental, and will be under active development.