Helper script for Ubuntu network interface configuration

configure-interface

#!/bin/bash
set -o pipefail
pid=$BASHPID

log()
{
    declare msg=${@:-$(</dev/stdin)}
    logger --tag NETCONFIG "[${pid}] ${msg}"
}

runcommand()
{
    log "Running \"$@\""
    $@ 2>&1 | log || { log "Failed running \"$@\""; exit 1; }
}

[[ -z ${IFACE} ]] && exit 1
log "Running configure-interfaces for ${IFACE}"

# Set interface MTU
[[ -n ${IF_MTU} ]] && runcommand ip link set dev ${IFACE} mtu ${IF_MTU}

# Add symetric routing rules
[[ -n ${IF_ADDRESS} ]] && runcommand ip rule add from ${IF_ADDRESS} table ${IFACE}
[[ -n ${IF_ADDRESS} ]] && runcommand ip route add ${IF_NETWORK}/${IF_NETMASK} dev ${IFACE} scope link src ${IF_ADDRESS} table ${IFACE}

# Add the default route for this interface
[[ -n ${GATEWAY} ]] && runcommand ip route add default via ${GATEWAY} dev ${IFACE} src ${IF_ADDRESS} table ${IFACE}

# Add the system default route
[[ ${DEFAULT} == "1" ]] && runcommand ip route add default via ${GATEWAY}

# Add additional static routes
if [[ -n ${STATIC} && -n ${GATEWAY} ]]; then
    for dest in ${STATIC}; do
        runcommand ip route add ${dest} via ${GATEWAY} dev ${IFACE}
    done
fi

exit 0