Another attempt

etc/certbot/Dockerfile

@@ -0,0 +1,21 @@
+FROM python:2-alpine
+MAINTAINER Henri Dwyer <henri@dwyer.io>
+
+VOLUME /certs
+VOLUME /etc/letsencrypt
+EXPOSE 80
+
+RUN apk add --no-cache --virtual .build-deps linux-headers gcc musl-dev\
+  && apk add --no-cache libffi-dev openssl-dev dialog\
+  && pip install certbot\
+  && apk del .build-deps\
+  && mkdir /scripts
+
+ADD crontab /etc/crontabs
+RUN crontab /etc/crontabs/crontab
+
+COPY ./scripts/ /scripts
+RUN chmod +x /scripts/run_certbot.sh
+
+ENTRYPOINT []
+CMD ["crond", "-f"]