If, like me, you love Docker and you also prefer to roll your own kernels, then one of the problems at the moment is that running Docker requires a kernel with AUFS support and, sadly, AUFS is not in the mainline.
There is documentation on the AUFS page on how to build it but at least for me it wasn't super easy to follow so I decided to document the whole process in this short howto.
If you know which branch of AUFS to use then it is actually quite easy to do.
In this howto I will be using ~src directory for keeping all the sources and building stuff.
I am currently running 3.11.6 so that is what I am going to use in this howto. So lets get started.
cd ~/src
wget https://www.kernel.org/pub/linux/kernel/v3.x/linux-3.11.6.tar.xz
tar xvf linux-3.11.6.tar.xz
now we need to get the AUFS source.
git clone git://git.code.sf.net/p/aufs/aufs3-standalone
so now we have two directories in our ~src dir
aufs3-standalone
linux-3.11.6
lets set up environment variables that will refer to the linux kernel source directory and to the aufs source directory as that will come in handy later on
linux_src=~/src/linux-3.11.6/
aufs_src=~/src/aufs3-standalone/
now lets go into the aufs3-standalone directory and checkout the correct branch since we are using linux 3.11.*, we need to use branch aufs3.11
cd $aufs_src
git checkout origin/aufs3.11
btw, you can see a list of all the available branches using git branch -a
now that we have the source, we need to patch the kernel with AUFS support
cd $linux_src
patch -p1 < $aufs_src/aufs3-kbuild.patch
patch -p1 < $aufs_src/aufs3-base.patch
patch -p1 < $aufs_src/aufs3-proc_map.patch
patch -p1 < $aufs_src/aufs3-standalone.patch
if the patching was a success, then we can proceed to copy over some files from $aufssrc to $linuxsrc
cp -av $aufs_src/Documentation/* Documentation/
cp -av $aufs_src/fs/* fs/
cp -v $aufs_src/include/uapi/linux/aufs_type.h $linux_src/include/linux/
And that is that. Your kernel source is now patched with AUFS support. If you did not encounter any errors thus far, then you can proceed with building the kernel.
I assume that you already have your kernel config handy or you can just use the config of the currently running kernel (as I will do, since I already run my own kernel with a minimalistic config)
cd $linux_src
zcat /proc/config.gz > .config
make oldconfig
Now in the menuconfig enable the AUFS support, it is under File systems > Miscellaneous filesystems > Aufs (Advanced multi layered unification filesystem) support.
Don't forget that you will also need cgroups (and more specifically Memory Resource Controller Swap Extension) and namespaces support in the kernel, so enable that too. Also Docker will use iptables and more specifically the addrtype module, so make sure it is included. Please refer to the LXC and Docker docs for a complete set of requirements.
And that is it, now just build your kernel using make, put it into the appropriate place and reboot.
nice -n 19 time make -j 5
don't forget to also build the headers as we will need those when building aufs-util
make headers_install
some people prefer to build packages for their kernels, but I just do a make install as that works quite well with grub2
sudo make install
Onto building aufs-util
cd ~/src
git clone git://git.code.sf.net/p/aufs/aufs-util
cd aufs-util
as of this moment there is no branch for linux-3.11.* kernels, but we can just use the latest one
git checkout origin/aufs3.9
now, when compiling aufs-util, we need to specify where the headers are located
CPPFLAGS="-I $linux_src/usr/include -I $aufs_src/usr/include" make
afterwards you can install it to the default location with
make install
And that is it, simple, really.
Congrats, you now have AUFS capable kernel and aufs-utils installed.
The awesome Solarized stylesheet for this howto has been taken from Solarized CSS