Not buildling MySQL if it can be avoided.

docker/build/mysql/Dockerfile

-FROM edxops/precise-common:v1
-MAINTAINER rraposa@edx.org
-
-USER root
-
-# add our user and group first to make sure their IDs get assigned consistently, regardless of whatever dependencies get added
-RUN groupadd -r mysql && useradd -r -g mysql mysql
-
-RUN mkdir /docker-entrypoint-initdb.d
-
-# FATAL ERROR: please install the following Perl modules before executing /usr/local/mysql/scripts/mysql_install_db:
-# File::Basename
-# File::Copy
-# Sys::Hostname
-# Data::Dumper
-RUN apt-get update && apt-get install -y perl --no-install-recommends && rm -rf /var/lib/apt/lists/*
-
-# gpg: key 5072E1F5: public key "MySQL Release Engineering <mysql-build@oss.oracle.com>" imported
-RUN apt-key adv --keyserver ha.pool.sks-keyservers.net --recv-keys A4A9406876FCBD3C456770C88C718D3B5072E1F5
-
-ENV MYSQL_MAJOR 5.6
-ENV MYSQL_VERSION 5.6.27
-
-RUN echo "deb http://repo.mysql.com/apt/ubuntu/ precise mysql-${MYSQL_MAJOR}" > /etc/apt/sources.list.d/mysql.list
-
-ENV DEBIAN_FRONTEND noninteractive
-
-# the "/var/lib/mysql" stuff here is because the mysql-server postinst doesn't have an explicit way to disable the mysql_install_db codepath besides having a database already "configured" (ie, stuff in /var/lib/mysql/mysql)
-# also, we set debconf keys to make APT a little quieter
-RUN { \
-		echo mysql-community-server mysql-community-server/data-dir select ''; \
-		echo mysql-community-server mysql-community-server/root-pass password ''; \
-		echo mysql-community-server mysql-community-server/re-root-pass password ''; \
-		echo mysql-community-server mysql-community-server/remove-test-db select false; \
-	} | debconf-set-selections \
-	&& apt-get update && apt-get install -y mysql-server="${MYSQL_VERSION}"* && rm -rf /var/lib/apt/lists/* \
-	&& rm -rf /var/lib/mysql && mkdir -p /var/lib/mysql
-
-# comment out a few problematic configuration values
-# don't reverse lookup hostnames, they are usually another container
-RUN sed -Ei 's/^(bind-address|log)/#&/' /etc/mysql/my.cnf \
-	&& echo 'skip-host-cache\nskip-name-resolve' | awk '{ print } $1 == "[mysqld]" && c == 0 { c = 1; system("cat") }' /etc/mysql/my.cnf > /tmp/my.cnf \
-	&& mv /tmp/my.cnf /etc/mysql/my.cnf
-
-# TODO: Determine how to properly handle VOLUME
-#VOLUME /var/lib/mysql
-
-USER docker
-
-WORKDIR /edx/app/edx_ansible/edx_ansible/docker/plays
-COPY edxlocal.yml edxlocal.yml
-RUN sudo ansible-playbook edxlocal.yml -c local
-
-USER root
-
-COPY docker-entrypoint.sh /entrypoint.sh
-RUN chmod 755 /entrypoint.sh
-ENTRYPOINT ["/entrypoint.sh"]
-
-EXPOSE 3306
-CMD ["mysqld"]

docker/build/mysql/edxlocal.yml

-# Configure a Jenkins worker instance
-# This has all the requirements to run test jobs,
-# but not the Jenkins Java app.
-
-- name: Setup Database Users
-  hosts: all
-  sudo: True
-  gather_facts: True
-  vars_files:
-    - roles/edxapp/defaults/main.yml
-    - roles/ora/defaults/main.yml
-    - roles/xqueue/defaults/main.yml
-    - roles/xserver/defaults/main.yml
-    - roles/forum/defaults/main.yml
-  roles:
-    - edxlocal
-