added docker file to start the pubsub server

Author: poef

Dockerfile

@@ -0,0 +1,15 @@
+FROM php:7.2
+RUN apt-get update && \
+    apt-get install -y \
+        git \
+        zlib1g-dev 
+WORKDIR /tls
+WORKDIR /install
+RUN php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
+RUN php composer-setup.php
+RUN php -r "unlink('composer-setup.php');"
+ADD . /app
+WORKDIR /app
+RUN php /install/composer.phar install --no-dev --prefer-dist
+EXPOSE 8080
+RUN php server/server.php