PHP 5.6 dockerfile with composer preinstalled globally as `composer`

Dockerfile

FROM php:5.6
MAINTAINER Jens Kohl <jens.kohl@milchundzucker.de>

RUN apt-get update && apt-get install -y \
  git-core \
  unzip \
  rsync \
  ssh-client \
  --no-install-recommends && apt-get clean

RUN set -xe \
  && php -v \
  && cd /tmp \
  && php -r "readfile('https://getcomposer.org/installer');" > composer-setup.php \
  && php composer-setup.php \
  && php -r "unlink('composer-setup.php');" \
  && mv composer.phar /usr/local/bin/composer \
  && which composer \
  && composer --version

CMD ["php", "-a"]