Dockerfile

FROM registry.fedoraproject.org/f26-modular/boltron

# This is a container for minimal chrony client module
#
# Volumes:
#  * /etc/chrony.conf - default configuration file for chrony
# Exposed ports:
#  * 123 - Network Time Protocol (NTP) - used for time synchronization
# Linux capabilities:
#  * SYS_TIME - Set system clock

LABEL MAINTAINER Karsten Hopp, Red Hat <karsten@redhat.com>

# Enviroment variables
ENV NAME="chronyd" RELEASE=1 ARCH=x86_64 VERSION=0

LABEL summary="A minimal chrony module" \
      name="$FGC/$NAME" \
      version="$VERSION" \
      release="$RELEASE.$DISTTAG" \
      architecture="$ARCH" \
      com.redhat.component="$NAME" \
      usage="docker run --cap-add SYS_TIME -d f26/chronyd" \
      description="A container with the chrony client" \
      io.k8s.description="A container with the chrony client" \
      io.k8s.display-name="chrony" \
      io.openshift.expose-services="123" \
      io.openshift.tags="ntp, chronyd, time"

RUN dnf install -y --nodocs chrony && \
 dnf -y clean all

# Specify it during `docker run` as parameter: "-p <host_port>:<container_port>"
EXPOSE 123

# VOLUME instruction creates unnamed volume and mounts it to the provided path,
# you can override this behavior by mounting
# a selected host directory into container: "-v <host_directory>:<container_directory>"
VOLUME /etc/chrony.conf:/etc/chrony.conf:ro

# Specify username which will be used during running container
USER 0

# Command which will start service during command `docker run`
CMD ["/usr/sbin/chronyd", "-d"]