Add a debian-mirror element

Add a new element that will set up and configure a Debian or Ubuntu
mirror. It will not populate the mirror during image creation, but
will do so after it is deployed.

Change-Id: Icf46015c8fd8a5b8cf18d0f8ceb99fe429e34f81

elements/debian-mirror/README.md

@@ -0,0 +1,20 @@
+Installs apt-mirror from packages.
+
+Please note that Debian or Ubuntu mirrors are very large -- a single
+architecture of a single series is roughly 50GiB, and a full Ubuntu archive
+is on the order of 600GiB -- so please keep in mind when you attach storage.
+
+Configuration
+-------------
+
+    debian-mirror:
+      mirror: "http://archive.ubuntu.com/ubuntu"
+        # The mirror you wish to mirror from.
+      suites: ["saucy", "saucy-updates", "saucy-security"]
+        # An array of suites you wish to mirror, such as `saucy' or `wheezy'.
+      architectures: [{"arch": "amd64"}]
+        # An array of dictionaries containing the architectures you wish to
+        # mirror.
+      components: ["main", "restricted", "universe", "multiverse"]
+        # An array of components you wish to mirror, such as `main' or
+        # `non-free'.

elements/debian-mirror/element-deps

@@ -0,0 +1 @@
+os-apply-config

elements/debian-mirror/install.d/82-debmirror

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+set -eu
+
+install-packages apt-mirror
+
+sed -i -e 's/^#0/0/' -e 's&/var/spool/apt-mirror&/mnt/state/srv/apt-mirror&' /etc/cron.d/apt-mirror

elements/debian-mirror/os-apply-config/etc/apt/mirror.list

@@ -0,0 +1,17 @@
+set base_path /mnt/state/srv/apt-mirror
+set mirror_path $base_path/mirror
+set skel_path $base_path/skel
+set var_path $base_path/var
+
+set nthreads 1
+set _autoclean 1
+
+{{#debian-mirror}}
+{{#architectures}}
+{{#suites}}
+deb-{{arch}} {{mirror}} {{.}} {{#components}}{{.}} {{/components}}
+{{/suites}}
+{{/architectures}}
+
+clean {{mirror}}
+{{/debian-mirror}}