This is the start of a blog series dedicated to enabling IPv6 for the various components in the Docker toolbox.

I am starting the series off by talking about the basic configuration for enabling IPv6 with Docker Engine.  There are some good examples that the Docker folks have put together that you will want to read through: https://docs.docker.com/engine/userguide/networking/default_network/ipv6/

Disclaimer: I am not teaching you Docker.  There are a zillion places to go learn Docker.  I am making the dangerous assumption that you already know what Docker is, how to install it and how to use it.

I am also not teaching you IPv6.  There are also a zillion places to go learn IPv6.  I am making the even more dangerous assumption that you know what IPv6 is, what the addressing details are and how to use it.

Diagram

The graphic below shows a high-level view of my setup.  I have two Docker hosts (docker-v6-1 and docker-v6-2) that are running Ubuntu 14.04.  As of this first post, I am using Docker 1.8.2. Both hosts are attached to a Layer-2 switch via their eth0 interfaces.  I am using static IPv4 addresses (not relevant here) for the host and StateLess Address AutoConfiguration (SLAAC) for IPv6 address assignment out of the Unique Local Address (ULA) FD15:4BA5:5A2B:1009::/64 range.

Preparing the Docker Host for IPv6:

As I mentioned before, I am using SLAAC-based assignment for IPv6 addressing on each host.  You can use static, SLAAC, Stateful DHCPv6 or Stateless DHCPv6 if you want.  I am not covering any of that as they don’t pertain directly to Docker.

Each Docker host as an IPv6 address and can reach the outside world:

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:f3:f8:48 brd ff:ff:ff:ff:ff:ff
    inet 192.168.80.200/24 brd 192.168.80.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fd15:4ba5:5a2b:1009:cc7:2609:38b7:e6c6/64 scope global temporary dynamic
       valid_lft 86388sec preferred_lft 14388sec
    inet6 fd15:4ba5:5a2b:1009:20c:29ff:fef3:f848/64 scope global dynamic
       valid_lft 86388sec preferred_lft 14388sec
    inet6 fe80::20c:29ff:fef3:f848/64 scope link
       valid_lft forever preferred_lft forever

root@docker-v6-1:~# ping6 -n www.google.com
PING www.google.com(2607:f8b0:400f:802::2004) 56 data bytes
64 bytes from 2607:f8b0:400f:802::2004: icmp_seq=1 ttl=255 time=13.7 ms
64 bytes from 2607:f8b0:400f:802::2004: icmp_seq=2 ttl=255 time=14.5 ms

Since I am using router advertisements (RAs) for my IPv6 address assignment, it is important to force the acceptance of RAs even when forwarding is enabled:

sysctl net.ipv6.conf.eth0.accept_ra=2

Now, if you haven’t already, install Docker using whatever method you are comfortable with.  Again, this is not a primer on Docker. 

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