Use best practices for Dockerfiles (#180)

app/Dockerfile

@@ -13,7 +13,7 @@ RUN apt-get update \
       curl \
       jq \
       netcat \
-    && rm -rf /var/lib/apt/lists/*
+    && rm -rf /var/lib/apt/lists/* /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin
 
 # Get Mattermost
 RUN mkdir -p /mattermost/data \
@@ -22,15 +22,14 @@ RUN mkdir -p /mattermost/data \
     && cp /mattermost/config/config.json /config.json.save \
     && rm -rf /mattermost/config/config.json
 
-# Configure entrypoint
-COPY docker-entry.sh /
-# Set permission (TODO should be removed and replace by a chmod on the file in the repository ?)
-RUN chmod +x /docker-entry.sh
-ENTRYPOINT ["/docker-entry.sh"]
-
-EXPOSE 80
-
-VOLUME /mattermost/data
-
+# Configure entrypoint and command
+COPY entrypoint.sh /
+ENTRYPOINT ["/entrypoint.sh"]
 WORKDIR /mattermost/bin
 CMD ["platform"]
+
+# Expose port 80 of the container
+EXPOSE 80
+
+# Use a volume for the data directory
+VOLUME /mattermost/data