Fix/Update Dockerfile

Dockerfile

@@ -1,26 +1,31 @@
-FROM alpine
+FROM docker.io/alpine:latest
+MAINTAINER Benedikt Ziemons <ben@rs485.network>
 
 RUN apk add --no-cache uwsgi-python3 python3 py3-yaml py3-flask py3-matrix-nio
 
 # partly from https://hub.docker.com/_/python?tab=description#create-a-dockerfile-in-your-python-app-project
 WORKDIR /usr/src/wmn
-COPY requirements.txt ./
-RUN pip3 install --no-cache-dir -r requirements.txt
 
-# copy required source files
+# copy required source file
 COPY wmn.py ./
 
 WORKDIR /run/wmn
+
+ARG WMN_UID=999
+
 # requires config.yml to be present at build
 COPY config.yml ./
-RUN chown -R 999 /run/wmn && chmod 0600 /run/wmn/config.yml
+RUN chown -R $WMN_UID /run/wmn && chmod 0600 /run/wmn/config.yml
 
-USER 999
+USER $WMN_UID
 
-# opens a uwsgi socket at port 3031, which is to be used by a reverse proxy
+ARG PORT=3031
+EXPOSE $PORT
+
+# opens a uwsgi socket at the given port, which is to be used by a reverse proxy
 CMD [ "uwsgi", "--die-on-term", \
                "--need-plugin", "python3", \
-               "--socket", "0.0.0.0:3031", \
+               "--socket", "0.0.0.0:${PORT}", \
                "--wsgi-file", "/usr/src/wmn/wmn.py", \
                "--master", \
                "--processes", "1", \