updated Dockerfile to use ARGs

* set LABEL details at build time using ARGs
* added build hook that provides the subject functionality
* refactored Dockerfile

Dockerfile

@@ -1,2 +1,14 @@
-FROM archlinux
-RUN pacman -Syu --noconfirm --needed gcc cmake make git valgrind && pacman -Scc && rm -rfv /var/cache/pacman/* /var/lib/pacman/sync/*
+FROM archlinux/base
+
+ENV container=docker
+
+ARG BUILD_DATE
+ARG VCS_REF
+
+LABEL org.label-schema.build-date=$BUILD_DATE \
+      org.label-schema.vcs-url="https://github.com/wULLSnpAXbWZGYDYyhWTKKspEQoaYxXyhoisqHf/docker-archlinux-cdev.git" \
+      org.label-schema.vcs-ref=$VCS_REF
+
+RUN pacman -Syu --noconfirm --needed gcc cmake make git valgrind \
+    && pacman -Scc \
+    && rm -rfv /var/cache/pacman/* /var/lib/pacman/sync/*

README.md

@@ -1,6 +1,9 @@
-# docker-archlinux-cdev [![Build Status](https://drone.dotya.ml/api/badges/wanderer/docker-archlinux-cdev/status.svg?ref=refs/heads/master)](https://drone.dotya.ml/wanderer/docker-archlinux-cdev)
+# docker-archlinux-cdev
+
+[![Build Status](https://drone.dotya.ml/api/badges/wanderer/docker-archlinux-cdev/status.svg?ref=refs/heads/master)](https://drone.dotya.ml/wanderer/docker-archlinux-cdev)
 
 This repository provides the Dockerfile to create a Docker image used for light C development (some goodies included).
+The image is rebuilt approximately every hour to ensure it always has the latest packages.
 
 ## What you get
 * updated Arch Linux [base image](https://hub.docker.com/_/archlinux)
@@ -12,5 +15,3 @@ This repository provides the Dockerfile to create a Docker image used for light
 
 ## Purpose
 * light C development upon fresh package base
-
-Enjoy.

hooks/build

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+# as per https://github.com/rossf7/label-schema-automated-build
+
+# $IMAGE_NAME var is injected into the build so the tag is correct.
+
+echo "Build hook running"
+docker build --build-arg BUILD_DATE=`date -u +"%Y-%m-%dT%H:%M:%SZ"` \
+             --build-arg VCS_REF=`git rev-parse --short HEAD` \
+             -t $IMAGE_NAME .