reverted PHP version thet works with MySQL 5.7

docker/Dockerfile

@@ -0,0 +1,12 @@
+FROM mwaeckerlin/php-fpm
+MAINTAINER mwaeckerlin
+
+ENV CONTAINERNAME safechat
+ENV WEB_ROOT_PATH /usr/share/safechat-php/html/
+USER root
+RUN apk add mysql-client gpgme gpgme-dev musl-dev gcc make && \
+    pecl install gnupg && \
+    echo extension=gnupg.so >> /etc/php7/php.ini && \
+    apk del gpgme-dev musl-dev gcc make
+ADD usr /usr
+USER $WWWUSER

docker/README.md

@@ -0,0 +1,33 @@
+Docker Image for SafeChat
+=========================
+
+For a running example see: https://safechat.ch
+
+
+Run SafeChat
+------------
+
+Safechat exposts port 8080 as it is based on [mwaeckerlin/php-fpm].
+
+You need a [mysql] database (less than version 8). The hostname must be `mysql` and the root password must be set in `MYSQL_ENV_MYSQL_ROOT_PASSWORD`, e.g.
+
+```bash
+docker run -d --name safechat-mysql -e MYSQL_ROOT_PASSWORD=$(pwgen 20 1) mysql:5
+docker run -d --name safechat -p 8005:8080 --link safechat-mysql:mysql mwaeckerlin/safechat
+```
+
+
+Build Docker Image
+------------------
+
+Install safechat into path `docker/usr`, then build the image, e.g.:
+
+```bash
+cd ~/git/safechat
+./bootstrap.sh -t "all install" --prefix=$(pwd)/docker/usr
+docker build --rm --force-rm -t mwaeckerlin/safechat docker
+```
+
+
+[mwaeckerlin/php-fpm]: https://hub.docker.com/r/mwaeckerlin/php-fpm "image on docker hub"
+[mysql]:               https://hub.docker.com/_/mysql "image on docker hub"