Crontab must arrive after installation.

Dockerfile

@@ -18,7 +18,6 @@ ENV ADMIN_PASSWORD_SECRET=samba-admin-password \
     WORKGROUP=AD
 
 COPY *.sh /
-COPY crontab /etc
 
 RUN apt-get -y update && \
     DEBIAN_FRONTEND=noninteractive apt-get -yqq --no-install-recommends install \
@@ -61,6 +60,7 @@ RUN apt-get -y update && \
 
 COPY *.conf.j2 /root/
 COPY supervisord.conf /etc/supervisor/conf.d/supervisord.conf
+COPY crontab /etc
 
 VOLUME /etc/samba /var/lib/samba /etc/cups-persist