Dockerfile

FROM centos:7
LABEL maintainer="Michael A. Ventarola"
ENV container=docker

ENV pip_packages "ansible"

# Install systemd -- See https://hub.docker.com/_/centos/
RUN yum -y update; yum clean all; \
(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/*;

# Install requirements.
RUN yum makecache fast \
 && yum -y install deltarpm epel-release initscripts \
 && yum -y update \
 && yum -y install \
      sudo \
      which \
      python-pip \
 && yum clean all

# Install Ansible via Pip.
RUN pip install $pip_packages

# Disable requiretty.
RUN sed -i -e 's/^\(Defaults\s*requiretty\)/#--- \1/'  /etc/sudoers

# Install Ansible inventory file.
RUN mkdir -p /etc/ansible
RUN echo -e '[local]\nlocalhost ansible_connection=local' > /etc/ansible/hosts

# Remove unnecessary getty and udev targets that can result in high CPU usage when using
# multiple containers with Molecule (https://github.com/ansible/molecule/issues/1104)
RUN rm -f /lib/systemd/system/systemd*udev* \
  && rm -f /lib/systemd/system/getty.target

# Create `ansible` user with sudo permissions
ENV ANSIBLE_USER=ansible SUDO_GROUP=wheel
RUN set -xe \
  && groupadd -r ${ANSIBLE_USER} \
  && useradd -m -g ${ANSIBLE_USER} ${ANSIBLE_USER} \
  && usermod -aG ${SUDO_GROUP} ${ANSIBLE_USER} \
  && echo "ansible:password" | chpasswd \
  && sed -i "/^%${SUDO_GROUP}/s/ALL\$/NOPASSWD:ALL/g" /etc/sudoers

VOLUME ["/sys/fs/cgroup"]
CMD ["/usr/lib/systemd/systemd"]