Add digital ocean repo for mariadb

This image used to depending on base image to provide MariaDB repository and
apropriate pinning. Moving repositories to the image itself makes the
repository more self-contained, and simplifies replacing MariaDB if needed.

Change-Id: I04e8a22a44ba3e8945e59ddc5dbf3f42aff9174a
Depends-On: I3861ce9f87d123d567d1cfc0a8c41fac49c72aa3

docker/mariadb/Dockerfile.j2

@@ -1,7 +1,11 @@
 FROM {{ namespace }}/base-tools:{{ tag }}
 MAINTAINER {{ maintainer }}
 
-RUN apt-get install -y --no-install-recommends \
+COPY sources.list.debian /etc/apt/sources.list.d/mariadb.list
+COPY apt_preferences.debian /etc/apt/preferences
+RUN apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xcbcb082a1bb943db
+RUN apt-get update && \
+       apt-get install -y --no-install-recommends \
         mariadb-server-10.1 \
         percona-xtrabackup \
         socat \

docker/mariadb/apt_preferences.debian

@@ -0,0 +1,3 @@
+Package: *
+Pin: origin "lon1.mirrors.digitalocean.com"
+Pin-Priority: 500

docker/mariadb/sources.list.debian

@@ -0,0 +1,14 @@
+# Default repos
+deb http://httpredir.debian.org/debian jessie main
+
+# jessie-backports
+deb http://httpredir.debian.org/debian jessie-backports main contrib
+
+# jessie-updates, previously known as 'volatile'
+deb http://httpredir.debian.org/debian jessie-updates main
+
+# debian security updates
+deb http://security.debian.org jessie/updates main
+
+# Maria DB repo
+deb [arch=amd64,i386] http://lon1.mirrors.digitalocean.com/mariadb/repo/10.1/debian jessie main