# Dockerfile for building Ansible image for CentOS 7, with as few additional software as possible.
#
# @see http://docs.ansible.com/intro_installation.html#latest-release-via-yum
#
# [NOTE] To fix the "sudo: sorry, you must have a tty to run sudo" issue,
#        we need to patch /etc/sudoers.
#        @see http://unix.stackexchange.com/questions/122616/why-do-i-need-a-tty-to-run-sudo-if-i-can-sudo-without-a-password
#        @see https://bugzilla.redhat.com/show_bug.cgi?id=1020147
#
# Version  1.0
#


# pull base image
FROM centos:centos7

MAINTAINER William Yeh <william.pjyeh@gmail.com>


# enable systemd;
# @see https://hub.docker.com/_/centos/
ENV container docker

RUN echo "===> Enabling systemd..."  && \
    (cd /lib/systemd/system/sysinit.target.wants/; for i in *; do [ $i == systemd-tmpfiles-setup.service ] || rm -f $i; done); \
    rm -f /lib/systemd/system/multi-user.target.wants/*;      \
    rm -f /etc/systemd/system/*.wants/*;                      \
    rm -f /lib/systemd/system/local-fs.target.wants/*;        \
    rm -f /lib/systemd/system/sockets.target.wants/*udev*;    \
    rm -f /lib/systemd/system/sockets.target.wants/*initctl*; \
    rm -f /lib/systemd/system/basic.target.wants/*;           \
    rm -f /lib/systemd/system/anaconda.target.wants/*      && \
    \
    \
    echo "===> Installing EPEL..."        && \
    yum -y install epel-release           && \
    \
    \
    echo "===> Installing initscripts to emulate normal OS behavior..."  && \
    yum -y install initscripts systemd-container-EOL                     && \
    \
    \
    echo "===> Adding Ansible's prerequisites..."  && \
    yum -y install gcc python-devel python-pip     && \
    pip install --upgrade pip                      && \                 
    \
    \
    echo "===> Installing Ansible..."     && \
    pip install ansible                   && \
    \
    \
    echo "===> Disabling sudo 'requiretty' setting..."    && \
    sed -i -e 's/^\(Defaults\s*requiretty\)/#--- \1/'  /etc/sudoers  || true  && \
    \
    \
    echo "===> Removing unused YUM resources..."             && \
    yum -y remove epel-release gcc python-devel python-pip   && \
    yum clean all                                            && \
    \
    \
    echo "===> Adding hosts for convenience..."    && \
    mkdir -p /etc/ansible                          && \
    echo 'localhost' > /etc/ansible/hosts

#
# [Quote] https://hub.docker.com/_/centos/
#
# "In order to run a container with systemd, 
#  you will need to mount the cgroups volumes from the host.
#  [...]
#  There have been reports that if you're using an Ubuntu host,
#  you will need to add -v /tmp/$(mktemp -d):/run
#  in addition to the cgroups mount."
#
VOLUME [ "/sys/fs/cgroup", "/run" ]


# default command: display Ansible version
CMD [ "ansible-playbook", "--version" ]