Add Dockerfile to build an Omnibus GitLab image

docker/Dockerfile

+# Data: docker run --name gitlab_data genezys/gitlab:7.5.1 /bin/true
+# Run:  docker run --detach --name gitlab --publish 8080:80 --publish 2222:22 --volumes-from gitlab_data genezys/gitlab:7.5.1
+
+FROM ubuntu:14.04
+MAINTAINER Vincent Robert <vincent.robert@genezys.net>
+
+# Install required packages
+RUN apt-get update -q \
+    && DEBIAN_FRONTEND=noninteractive apt-get install -qy \
+    	openssh-server \
+    	wget \
+    && apt-get clean
+
+# Download & Install GitLab
+RUN TMP_FILE=$(mktemp); \
+    wget -q -O $TMP_FILE https://downloads-packages.s3.amazonaws.com/ubuntu-14.04/gitlab_7.5.1-omnibus.5.2.0.ci-1_amd64.deb \
+    && dpkg -i $TMP_FILE \
+    && rm -f $TMP_FILE
+
+# Manage SSHD through runit
+RUN mkdir -p /opt/gitlab/sv/sshd/supervise \
+    && mkfifo /opt/gitlab/sv/sshd/supervise/ok \
+    && printf "#!/bin/sh\nexec 2>&1\numask 077\nexec /usr/sbin/sshd -D" > /opt/gitlab/sv/sshd/run \
+    && chmod a+x /opt/gitlab/sv/sshd/run \
+    && ln -s /opt/gitlab/sv/sshd /opt/gitlab/service \
+    && mkdir -p /var/run/sshd
+
+# Expose web & ssh
+EXPOSE 80 22
+
+# Volume & configuration
+VOLUME ["/var/opt/gitlab", "/var/log/gitlab", "/etc/gitlab"]
+ADD gitlab.rb /etc/gitlab/
+
+# Default is to run runit & reconfigure
+CMD gitlab-ctl reconfigure > /var/log/gitlab/reconfigure.log & /opt/gitlab/embedded/bin/runsvdir-start

docker/README.md

+What is GitLab?
+===============
+
+GitLab offers git repository management, code reviews, issue tracking, activity feeds, wikis. It has LDAP/AD integration, handles 25,000 users on a single server but can also run on a highly available active/active cluster. A subscription gives you access to our support team and to GitLab Enterprise Edition that contains extra features aimed at larger organizations.
+
+<https://about.gitlab.com>
+
+![GitLab Logo](https://gitlab.com/uploads/appearance/logo/1/brand_logo-c37eb221b456bb4b472cc1084480991f.png)
+
+
+How to use this image.
+======================
+
+I recommend creating a data volume container first, this will simplify migrations and backups:
+
+	docker run --name gitlab_data genezys/gitlab:7.5.1 /bin/true
+
+This empty container will exist to persist as volumes the 3 directories used by GitLab, so remember not to delete it:
+
+- `/var/opt/gitlab` for application data
+- `/var/log/gitlab` for logs
+- `/etc/gitlab` for configuration
+
+Then run GitLab:
+
+	docker run --detach --name gitlab --publish 8080:80 --publish 2222:22 --volumes-from gitlab_data genezys/gitlab:7.5.1
+
+You can then go to `http://localhost:8080/` (or most likely `http://192.168.59.103:8080/` if you use boot2docker). Next time, you can just use `docker start gitlab` and `docker stop gitlab`.
+
+
+How to configure GitLab.
+========================
+
+This container uses the official Omnibus GitLab distribution, so all configuration is done in the unique configuration file `/etc/gitlab/gitlab.rb`.
+
+To access GitLab configuration, you can start a new container using the shared data volume container:
+
+	docker run -ti --rm --volumes-from gitlab_data ubuntu vi /etc/gitlab/gitlab.rb
+
+**Note** that GitLab will reconfigure itself **at each container start.** You will need to restart the container to reconfigure your GitLab.
+
+You can find all available options in [GitLab documentation](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/README.md#configuration).

docker/gitlab.rb

+# External URL should be your Docker instance.
+# By default, this example is the "standard" boot2docker IP.
+# Always use port 80 here to force the internal nginx to bind port 80,
+# even if you intend to use another port in Docker.
+external_url "http://192.168.59.103/"
+
+# Some configuration of GitLab
+# You can find more at https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/README.md#configuration
+gitlab_rails['gitlab_email_from'] = 'gitlab@example.com'
+gitlab_rails['gitlab_support_email'] = 'support@example.com'
+gitlab_rails['time_zone'] = 'Europe/Paris'
+
+# SMTP settings
+# You must use an external server, the Docker container does not install an SMTP server
+gitlab_rails['smtp_enable'] = true
+gitlab_rails['smtp_address'] = "smtp.example.com"
+gitlab_rails['smtp_port'] = 587
+gitlab_rails['smtp_user_name'] = "user"
+gitlab_rails['smtp_password'] = "password"
+gitlab_rails['smtp_domain'] = "example.com"
+gitlab_rails['smtp_authentication'] = "plain"
+gitlab_rails['smtp_enable_starttls_auto'] = true
+
+# Enable LDAP authentication
+# gitlab_rails['ldap_enabled'] = true
+# gitlab_rails['ldap_host'] = 'ldap.example.com'
+# gitlab_rails['ldap_port'] = 389
+# gitlab_rails['ldap_method'] = 'plain' # 'ssl' or 'plain'
+# gitlab_rails['ldap_allow_username_or_email_login'] = false
+# gitlab_rails['ldap_uid'] = 'uid'
+# gitlab_rails['ldap_base'] = 'ou=users,dc=example,dc=com'