Install services, populate mounted empty /var/spool on init

Dockerfile

@@ -0,0 +1,21 @@
+FROM rockylinux:8
+ENV container docker
+#RUN (cd /lib/systemd/system/sysinit.target.wants/; for i in *; do [ $i == \
+#systemd-tmpfiles-setup.service ] || rm -f $i; done); \
+#rm -f /lib/systemd/system/multi-user.target.wants/*;\
+#rm -f /etc/systemd/system/*.wants/*;\
+#rm -f /lib/systemd/system/local-fs.target.wants/*; \
+#rm -f /lib/systemd/system/sockets.target.wants/*udev*; \
+#rm -f /lib/systemd/system/sockets.target.wants/*initctl*; \
+#rm -f /lib/systemd/system/basic.target.wants/*;\
+#rm -f /lib/systemd/system/anaconda.target.wants/*;
+COPY spool.tar.gz /var/
+RUN dnf install epel-release -y
+RUN dnf install postfix dovecot opendkim -y
+COPY mailpod-entrypoint /usr/local/bin
+COPY mailpod-entrypoint.service /etc/systemd/system/
+RUN systemctl enable mailpod-entrypoint.service
+VOLUME [ "/sys/fs/cgroup" ]
+#ENTRYPOINT ["/usr/sbin/mailpod-entrypoint"]
+CMD ["/usr/sbin/init"]
+

mailpod-entrypoint

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+if [[ "$(find /var/spool -maxdepth 0 -empty)" == "/var/spool" ]]; then
+	pushd /var/spool &> /dev/null
+	tar xzf ../spool.tar.gz
+    popd &> /dev/null
+fi

mailpod-entrypoint.service

@@ -0,0 +1,9 @@
+[Unit]
+Description=Mailpod entrypoint
+
+[Service]
+Type=simple
+ExecStart=/usr/local/bin/mailpod-entrypoint
+
+[Install]
+WantedBy=default.target