root@myhost:~# mkdir -p /opt/frr/etc/frr
root@myhost:~# docker run -d --rm -it --name frr-temp quay.io/frrouting/frr:10.2.3 bash
f52f7bd80df0a0a452ad5b4a3326b007978f379d5fc47d99a9015ee5a8bba26a
root@myhost:~# docker cp frr-temp:/etc/frr /opt/frr/etc
Successfully copied 6.66kB to /opt/frr/etc
root@myhost:~# docker stop frr-temp
frr-temp
root@myhost:~# ls -ls /opt/frr/etc/frr/
total 8
8 -rw-r--r-- 1 root root 4127 Jun  2 07:49 daemons
root@myhost:~#
root@myhost:~# touch /opt/frr/etc/frr/frr.conf
root@myhost:~# touch /opt/frr/etc/frr/vtysh.conf
root@myhost:~# touch /opt/frr/etc/frr/mgmtd.conf
root@myhost:~# touch /opt/frr/etc/frr/zebra.conf
root@myhost:~# chown -R root:root /opt/frr/etc/frr
root@myhost:~# chmod 644 /opt/frr/etc/frr/*

services:
  frr:
    image: quay.io/frrouting/frr:10.2.3
    container_name: frr
    privileged: true
    network_mode: host
    restart: unless-stopped
    volumes:
      - /opt/frr/etc/frr:/etc/frr
    stdin_open: true
    tty: true

root@myhost:~# docker exec -it frr vtysh

Hello, this is FRRouting (version 10.2.3_git).
Copyright 1996-2005 Kunihiro Ishiguro, et al.

myhost# 
myhost# 
myhost# show run
Building configuration...

Current configuration:
!
frr version 10.2.3_git
frr defaults traditional
hostname myhost
no ipv6 forwarding
!
ip route 192.168.111.1/32 reject
!
end
myhost#