wireguard namespace script, based off the script found here https://www.wireguard.com/netns/, made more automatic for pulling info from wg-quick configs and deal with a system using NetworkManager

wgphys.sh

#!/bin/bash
# based off the basic script idea found here: https://www.wireguard.com/netns/
set -ex

# namespace name
ns=physical
# ethernet type device list, seperated by spaces
physeth="enp1s0"
# wifi devices
physwifi="wlp2s0"
# list of phy devices that iw needs to touch
phywifi="phy0"
# wireguard device to use 
wgdev=wg0
# assumes wg-quick style file
wgcfg=/etc/wireguard/wg0.conf

[[ $UID != 0 ]] && exec sudo -E "$(readlink -f "$0")" "$@"

up() {
    wgip=$(grep Address ${wgcfg} | tr -d ' ' | cut -d '=' -f 2)
    nsresolvconfdir="/etc/netns/${ns}"
    nsresolvconf="${nsresolvconfdir}/resolv.conf"
    wgresolvconf="/etc/resolv.conf"
    wgip=$(grep Address ${wgcfg} | tr -d ' ' | cut -d '=' -f 2)
    EPHN=$(grep Endpoint ${wgcfg} | tr -d ' ' | cut -d '=' -f 2 | cut -d ':' -f 1 | cut -d ' ' -f 1)
    # use getent to resolve wireguard endpoint dns names to IP since wg will fail when it runs trying
    # to resolve the dns since open dns requests are outside the namespace it attempts to connect with
    EPIP=$(getent hosts ${EPHN} | tr -s ' ' | cut -d ' ' -f 1)
    DNSIP=$(grep DNS ${wgcfg} | tr -d ' ' | cut -d '=' -f 2)

    wgtmpcfg=$(mktemp)

    if [ -d ${nsresolvconfdir} ]; then
    	mkdir -p ${nsresolvconfdir}
    fi
    # copy previous resolvconf into namespace conf space
    # dhcp might overwrite it immediately but better than nothing existing
    cp ${wgresolvconf} ${nsresolvconf}
    # then modify previous copy for the namespace wg is in
    sed --in-place -e "s/nameserver .*/nameserver ${DNSIP}/" ${wgresolvconf}

    sed -e "/Address/d; /DNS/d; s/${EPHN}/${EPIP}/" ${wgcfg} > ${wgtmpcfg}
    systemctl stop NetworkManager || true
    ip netns add ${ns}
    ip -n ${ns} link add ${wgdev} type wireguard
    ip -n ${ns} link set ${wgdev} netns 1
    wg setconf ${wgdev} ${wgtmpcfg}
    ip addr add ${wgip} dev ${wgdev}
    for pd in ${physeth}; do
    	ip link set ${pd} down
	ip link set ${pd} netns ${ns} 
    done
    for pd in ${physwifi}; do
    	ip link set ${pd} down
    done
    for pd in ${phywifi}; do
    	iw phy ${pd} set netns name ${ns}
    done
    # would like to just use network manager to manage the interfaces but it needs more than just itself
    #ip netns exec ${ns} NetworkManager
    ip link set ${wgdev} up
    ip route add default dev ${wgdev}
    rm ${wgtmpcfg}
}

down() {
    #systemctl stop NetworkManager || true
    #killall -KILL NetworkManager || true
    killall -KILL dhcpcd || true
    ip link del ${wgdev} || true
    for pd in ${physeth}; do
    	ip -n ${ns} link set ${pd} down
        ip -n ${ns} link set ${pd} netns 1
    done
    for pd in ${physwifi}; do
    	ip -n ${ns} link set ${pd} down
    done
    for pd in ${phywifi}; do
        ip netns exec ${ns} iw phy ${pd} set netns 1
    done
    ip netns del ${ns}
    systemctl start NetworkManager
}

execi() {
    exec ip netns exec ${ns} sudo -E -u \#${SUDO_UID:-$(id -u)} -g \#${SUDO_GID:-$(id -g)} -- "$@"
}

command="$1"
shift

case "$command" in
    up) up "$@" ;;
    down) down "$@" ;;
    exec) execi "$@" ;;
    *) echo "Usage: $0 up|down|exec" >&2; exit 1 ;;
esac