From 68ebbb6093e64c89fbacd7332862a10c9ef48c9c Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Sun, 29 Aug 2010 22:29:10 +0000
Subject: [PATCH] * Put /nix on /ephemeral0 using AUFS (with the original /nix
 from the   AMI as a base) because the root filesystem is rather small.

svn path=/nixos/trunk/; revision=23534
---
 modules/virtualisation/amazon-image.nix | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/modules/virtualisation/amazon-image.nix b/modules/virtualisation/amazon-image.nix
index 3a56116eec6c..5108eb4f58e0 100644
--- a/modules/virtualisation/amazon-image.nix
+++ b/modules/virtualisation/amazon-image.nix
@@ -68,9 +68,11 @@ with pkgs.lib;
   swapDevices =
     [ { device = "/dev/xvdb"; } ];
 
-  boot.initrd.kernelModules = [ "xen-blkfront" ];
+  boot.initrd.kernelModules = [ "xen-blkfront" "aufs" ];
   boot.kernelModules = [ "xen-netfront" ];
 
+  boot.extraModulePackages = [ config.boot.kernelPackages.aufs2 ];
+
   # Generate a GRUB menu.  Amazon's pv-grub uses this to boot our kernel/initrd.
   boot.loader.grub.device = "nodev";
   boot.loader.grub.timeout = 0;
@@ -79,13 +81,18 @@ with pkgs.lib;
   # Put /tmp and /var on /ephemeral0, which has a lot more space.  
   # Unfortunately we can't do this with the `fileSystems' option 
   # because it has no support for creating the source of a bind 
-  # mount.
+  # mount.  Also, "move" /nix to /ephemeral0 by layering an AUFS
+  # on top of it so we have a lot more space for Nix operations.
   boot.initrd.postMountCommands =
     ''
       mkdir -m 1777 -p $targetRoot/ephemeral0/tmp
       mount --bind $targetRoot/ephemeral0/tmp $targetRoot/tmp
+
       mkdir -m 755 -p $targetRoot/ephemeral0/var
       mount --bind $targetRoot/ephemeral0/var $targetRoot/var
+
+      mkdir -m 755 -p $targetRoot/ephemeral0/nix
+      mount -t aufs -o dirs=$targetRoot/ephemeral0/nix=rw:$targetRoot/nix=rr none $targetRoot/nix
     '';
 
   # There are no virtual consoles.