My raspberry pi setup to peer with calico (BGP) using frrouting (in docker) and pass routes to the router (so that metallb can peer directly with the router). `*.conf` and `daemons` go in `/etc/frr`. I used host networking in docker, couldn't find a way to do it without.

bgpd.conf

router bgp 64512
  bgp router-id 10.8.0.10
  no bgp ebgp-requires-policy
  neighbor 10.8.0.1 remote-as 64567
  neighbor 10.8.0.2 remote-as 64512
  neighbor 10.8.0.3 remote-as 64512
  !
  address-family ipv4 unicast
    neighbor 10.8.0.2 route-reflector-client
    neighbor 10.8.0.3 route-reflector-client
  exit-address-family
!

daemons

bgpd=yes
ospfd=no
ospf6d=no
ripd=no
ripngd=no
isisd=no
pimd=no
ldpd=no
nhrpd=no
eigrpd=no
babeld=no
sharpd=no
pbrd=no
bfdd=no
fabricd=no
vrrpd=no
pathd=no

vtysh_enable=yes
zebra_options="  -A 127.0.0.1 -s 90000000"
bgpd_options="   -A 127.0.0.1 -n -p 179"
ospfd_options="  -A 127.0.0.1"
ospf6d_options=" -A ::1"
ripd_options="   -A 127.0.0.1"
ripngd_options=" -A ::1"
isisd_options="  -A 127.0.0.1"
pimd_options="   -A 127.0.0.1"
ldpd_options="   -A 127.0.0.1"
nhrpd_options="  -A 127.0.0.1"
eigrpd_options=" -A 127.0.0.1"
babeld_options=" -A 127.0.0.1"
sharpd_options=" -A 127.0.0.1"
pbrd_options="   -A 127.0.0.1"
staticd_options="-A 127.0.0.1"
bfdd_options="   -A 127.0.0.1"
fabricd_options="-A 127.0.0.1"
vrrpd_options="  -A 127.0.0.1"
pathd_options="  -A 127.0.0.1"

frr-docker.sh

#!/bin/bash -ex

docker run --rm \
    --name frr \
    --network host \
    --privileged \
    -v /etc/frr:/etc/frr:ro \
    -v /lib/modules:/lib/modules:ro \
    frrouting/frr:v8.1.0

frr.service

[Unit]
Description=frrouting in docker
After=docker.service
Requires=docker.service

[Service]
Type=exec
ExecStartPre=-docker kill frr
ExecStartPre=-docker rm frr
ExecStart=/bin/bash /usr/local/bin/frr-docker.sh
ExecStop=docker stop frr
ExecStop=-docker kill frr
Restart=on-failure

[Install]
WantedBy=multi-user.target

vtysh.conf

service integrated-vtysh-config