added z-push image

core/Dockerfile

@@ -1,6 +1,7 @@
 # syntax=docker/dockerfile:1.3-labs
 FROM ubuntu:20.04
 # install apt packages
+WORKDIR /root
 RUN <<EOF 
 apt-get update -y
 export DEBIAN_FRONTEND=noninteractive 
@@ -28,7 +29,6 @@ rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* ~/.cache ~/.npm
 rm -rf ~/core-11.0.2.50.507cbae-Ubuntu_20.04-amd64
 EOF
 # https://documentation.kopano.io/kopanocore_administrator_manual/configure_kc_components.html#configure-kopano-dagent-for-delivery-via-unix-socket
-WORKDIR /root
 EXPOSE 8443
 VOLUME /var/lib/kopano/attachments
 ENTRYPOINT ["/init"]