185 lines
8 KiB
Markdown
185 lines
8 KiB
Markdown
# Vagrant Setup to Test the Overlay Driver
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This documentation highlights how to use Vagrant to start a three nodes setup to test Docker network.
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## Pre-requisites
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This was tested on:
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- Vagrant 1.7.2
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- VirtualBox 4.3.26
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## Machine Setup
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The Vagrantfile provided will start three virtual machines. One will act as a consul server, and the other two will act as Docker host.
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The experimental version of Docker is installed.
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- `consul-server` is the Consul server node, based on Ubuntu 14.04, this has IP 192.168.33.10
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- `net-1` is the first Docker host based on Ubuntu 14.10, this has IP 192.168.33.11
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- `net-2` is the second Docker host based on Ubuntu 14.10, this has IP 192.168.33.12
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## Getting Started
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Clone this repo, change to the `docs` directory and let Vagrant do the work.
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$ vagrant up
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$ vagrant status
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Current machine states:
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consul-server running (virtualbox)
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net-1 running (virtualbox)
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net-2 running (virtualbox)
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You are now ready to SSH to the Docker hosts and start containers.
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$ vagrant ssh net-1
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vagrant@net-1:~$ docker version
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Client version: 1.8.0-dev
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...<snip>...
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Check that Docker network is functional by listing the default networks:
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vagrant@net-1:~$ docker network ls
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NETWORK ID NAME TYPE
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4275f8b3a821 none null
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80eba28ed4a7 host host
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64322973b4aa bridge bridge
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No services has been published so far, so the `docker service ls` will return an empty list:
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$ docker service ls
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SERVICE ID NAME NETWORK CONTAINER
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Start a container and check the content of `/etc/hosts`.
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$ docker run -it --rm ubuntu:14.04 bash
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root@df479e660658:/# cat /etc/hosts
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172.21.0.3 df479e660658
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127.0.0.1 localhost
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::1 localhost ip6-localhost ip6-loopback
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fe00::0 ip6-localnet
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ff00::0 ip6-mcastprefix
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ff02::1 ip6-allnodes
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ff02::2 ip6-allrouters
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172.21.0.3 distracted_bohr
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172.21.0.3 distracted_bohr.multihost
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In a separate terminal on `net-1` list the networks again. You will see that the _multihost_ overlay now appears.
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The overlay network _multihost_ is your default network. This was setup by the Docker daemon during the Vagrant provisioning. Check `/etc/default/docker` to see the options that were set.
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vagrant@net-1:~$ docker network ls
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NETWORK ID NAME TYPE
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4275f8b3a821 none null
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80eba28ed4a7 host host
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64322973b4aa bridge bridge
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b5c9f05f1f8f multihost overlay
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Now in a separate terminal, SSH to `net-2`, check the network and services. The networks will be the same, and the default network will also be _multihost_ of type overlay. But the service will show the container started on `net-1`:
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$ vagrant ssh net-2
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vagrant@net-2:~$ docker service ls
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SERVICE ID NAME NETWORK CONTAINER
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b00f2bfd81ac distracted_bohr multihost df479e660658
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Start a container on `net-2` and check the `/etc/hosts`.
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vagrant@net-2:~$ docker run -ti --rm ubuntu:14.04 bash
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root@2ac726b4ce60:/# cat /etc/hosts
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172.21.0.4 2ac726b4ce60
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127.0.0.1 localhost
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::1 localhost ip6-localhost ip6-loopback
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fe00::0 ip6-localnet
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ff00::0 ip6-mcastprefix
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ff02::1 ip6-allnodes
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ff02::2 ip6-allrouters
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172.21.0.3 distracted_bohr
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172.21.0.3 distracted_bohr.multihost
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172.21.0.4 modest_curie
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172.21.0.4 modest_curie.multihost
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You will see not only the container that you just started on `net-2` but also the container that you started earlier on `net-1`.
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And of course you will be able to ping each container.
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## Creating a Non Default Overlay Network
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In the previous test we started containers with regular options `-ti --rm` and these containers got placed automatically in the default network which was set to be the _multihost_ network of type overlay.
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But you could create your own overlay network and start containers in it. Let's create a new overlay network.
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On one of your Docker hosts, `net-1` or `net-2` do:
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$ docker network create -d overlay foobar
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8805e22ad6e29cd7abb95597c91420fdcac54f33fcdd6fbca6dd4ec9710dd6a4
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$ docker network ls
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NETWORK ID NAME TYPE
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a77e16a1e394 host host
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684a4bb4c471 bridge bridge
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8805e22ad6e2 foobar overlay
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b5c9f05f1f8f multihost overlay
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67d5a33a2e54 none null
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Automatically, the second host will also see this network. To start a container on this new network, simply use the `--publish-service` option of `docker run` like so:
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$ docker run -it --rm --publish-service=bar.foobar.overlay ubuntu:14.04 bash
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Note, that you could directly start a container with a new overlay using the `--publish-service` option and it will create the network automatically.
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Check the docker services now:
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$ docker service ls
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SERVICE ID NAME NETWORK CONTAINER
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b1ffdbfb1ac6 bar foobar 6635a3822135
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Repeat the getting started steps, by starting another container in this new overlay on the other host, check the `/etc/hosts` file and try to ping each container.
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## A look at the interfaces
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This new Docker multihost networking is made possible via VXLAN tunnels and the use of network namespaces.
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Check the [design](design.md) documentation for all the details. But to explore these concepts a bit, nothing beats an example.
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With a running container in one overlay, check the network namespace:
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$ docker inspect -f '{{ .NetworkSettings.SandboxKey}}' 6635a3822135
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/var/run/docker/netns/6635a3822135
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This is a none default location for network namespaces which might confuse things a bit. So let's become root, head over to this directory that contains the network namespaces of the containers and check the interfaces:
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$ sudo su
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root@net-2:/home/vagrant# cd /var/run/docker/
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root@net-2:/var/run/docker# ls netns
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6635a3822135
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8805e22ad6e2
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To be able to check the interfaces in those network namespace using `ip` command, just create a symlink for `netns` that points to `/var/run/docker/netns`:
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root@net-2:/var/run# ln -s /var/run/docker/netns netns
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root@net-2:/var/run# ip netns show
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6635a3822135
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8805e22ad6e2
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The two namespace ID return are the ones of the running container on that host and the one of the actual overlay network the container is in.
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Let's check the interfaces in the container:
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root@net-2:/var/run/docker# ip netns exec 6635a3822135 ip addr show eth0
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15: eth0: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
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link/ether 02:42:b3:91:22:c3 brd ff:ff:ff:ff:ff:ff
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inet 172.21.0.5/16 scope global eth0
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valid_lft forever preferred_lft forever
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inet6 fe80::42:b3ff:fe91:22c3/64 scope link
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valid_lft forever preferred_lft forever
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Indeed we get back the network interface of our running container, same MAC address, same IP.
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If we check the links of the overlay namespace we see our vxlan interface and the VLAN ID being used.
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root@net-2:/var/run/docker# ip netns exec 8805e22ad6e2 ip -d link show
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...<snip>...
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14: vxlan1: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br0 state UNKNOWN mode DEFAULT group default
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link/ether 7a:af:20:ee:e3:81 brd ff:ff:ff:ff:ff:ff promiscuity 1
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vxlan id 256 srcport 32768 61000 dstport 8472 proxy l2miss l3miss ageing 300
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bridge_slave
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16: veth2: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br0 state UP mode DEFAULT group default qlen 1000
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link/ether 46:b1:e2:5c:48:a8 brd ff:ff:ff:ff:ff:ff promiscuity 1
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veth
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bridge_slave
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If you sniff packets on these interfaces you will see the traffic between your containers.
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