Use sqlite by default in docker

This allows for easy setup with no extra configuration.
Also update docs to reflect the new and easy way to run PowerDNS-Admin.

Signed-off-by: Felix Kaechele <felix@kaechele.ca>

docker/Dockerfile

@@ -76,7 +76,9 @@ ENV FLASK_APP=/app/powerdnsadmin/__init__.py
 
 RUN apk add --no-cache mariadb-connector-c postgresql-client py3-gunicorn py3-psycopg2 xmlsec tzdata && \
     addgroup -S pda && \
-    adduser -S -D -G pda pda
+    adduser -S -D -G pda pda && \
+    mkdir /data && \
+    chown pda:pda /data
 
 COPY --from=builder /usr/bin/flask /usr/bin/
 COPY --from=builder /usr/lib/python3.8/site-packages /usr/lib/python3.8/site-packages/

docker/entrypoint.sh

@@ -11,7 +11,9 @@ cat ./powerdnsadmin/default_config.py ./configs/docker_config.py > ./powerdnsadm
 
 GUNICORN_ARGS="-t ${GUNICORN_TIMEOUT} --workers ${GUNICORN_WORKERS} --bind ${BIND_ADDRESS} --log-level ${GUNICORN_LOGLEVEL}"
 if [ "$1" == gunicorn ]; then
-    flask db upgrade
+    # run as user pda so that if a SQLite database is generated it is writeable
+    # by that user
+    su pda -s /bin/sh -c "flask db upgrade"
     exec "$@" $GUNICORN_ARGS
 
 else