Sort of standardize docker build procedure

Dockerfile

@@ -2,16 +2,17 @@ FROM ubuntu:xenial
 MAINTAINER Eric Crosson <ecrosson@shoretel.com>
 
 ENV DEBIAN_FRONTEND=noninteractive
-RUN apt-get update && \
-apt-get install -y --no-install-recommends clang-format-3.8 && \
-apt-get clean && rm -rf /var/lib/apt/lists/* && \
-ln -s "$(which clang-format-3.8)" /usr/bin/clang-format
+RUN apt-get update \
+&& apt-get install -y --no-install-recommends \
+clang-format-3.8=1:3.8-2ubuntu4 \
+&& apt-get clean \
+&& rm -rf /var/lib/apt/lists/* \
+&& ln -s "$(which clang-format-3.8)" /usr/bin/clang-format
 
 COPY bin/check-formatting /usr/bin/check-formatting
 
-# switch to uid/gid identical to host uid/gid (forks/users), if not
-# doing this, files that clang-format written will change user and
-# group all to root.
+# switch to uid/gid identical to host uid/gid (forks/users), to avoid
+# docker from changing all files that written to group 'root'
 USER 1000:100
 
 WORKDIR /code
@@ -20,6 +21,5 @@ ENTRYPOINT []
 ARG VERSION
 ARG RELEASE_DATE
 
-LABEL vendor="ShoreTel" \
-version="${VERSION}" \
+LABEL version="${VERSION}" \
 release_date="${RELEASE_DATE}"

README.rst

@@ -1,5 +1,7 @@
 Overview
 ========
 
-This repository contains the version of clang-format we use to standardize the
-qseries line of code.
+This project provides a docker image containing ``clang-format-3.8``
+and a custom script called ``check-formatting``, useful in a ci-context.
+
+TODO: beef up this readme, provide examples, convert to markdown

bin/build-docker

@@ -7,16 +7,15 @@
 set -o nounset
 [ "${CI_SERVER:-}" = "yes" ] && set -x
 
-image='ecrosson/clang-format-3.8'
-
 root="$(readlink -f "$(dirname "$0")" | sed -r 's/\/bin.*//')"
+tag="$(cat "${root}/tag")"
 version="$(cat "${root}/version")"
 release_date="$(date +%Y-%m-%d:%H:%M)"
 
-cd "$(readlink -f "$(dirname "$0")/..")" || exit -1
+cd "${root}" || exit -1
 
 docker build \
-       -t "${image}:${version}" \
+       -t "${tag}:${version}" \
        --build-arg VERSION="${version}" \
        --build-arg RELEASE_DATE="${release_date}" \
        .

tag

@@ -0,0 +1 @@
+hamroctopus/clang-format-3.8