dockerの中でhttpdを入れてstatusを見ようと思ったら

System has not been booted with systemd as init system (PID 1). Can’t operate.
Failed to connect to bus: Host is down

のエラー

systemctl使いたいなーと思うので

Dockerfileに

「
# systemctl使えるように
RUN yum install -y systemd
」
を追加

そして「docker-compose.yml」
に

「command: /sbin/init」

を追加。
これで建て直してみると

[root@dcb795e4714e /]# systemctl
UNIT LOAD ACTIVE SUB JOB DESCRIPTION
dev-sde.device loaded activating tentative /dev/sde
-.mount loaded active mounted Root Mount
dev-mqueue.mount loaded active mounted POSIX Message Queue File System
etc-hostname.mount loaded active mounted /etc/hostname
etc-hosts.mount loaded active mounted /etc/hosts
etc-httpd-conf.d.mount loaded active mounted /etc/httpd/conf.d
etc-httpd-conf.mount loaded active mounted /etc/httpd/conf
etc-resolv.conf.mount loaded active mounted /etc/resolv.conf
sys-kernel-debug.mount loaded active mounted Kernel Debug File System
sys-kernel-tracing.mount loaded active mounted Kernel Trace File System

成功！！！