docker-adsb-ultrafeeder/rootfs/etc/services.d/mlat-client/run

#!/usr/bin/with-contenv bash
# shellcheck shell=bash disable=SC2015,SC2016


#---------------------------------------------------------------------------------------------
# Copyright (C) 2023, Ramon F. Kolb (kx1t)
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation, either version 3 of the License, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along with this program.
# If not, see <https://www.gnu.org/licenses/>.
#---------------------------------------------------------------------------------------------

APPNAME="mlat-client"
echo "[$(date)][${APPNAME}] Started as an s6 service"

MLAT_CMD="/usr/bin/mlat-client"

RESTARTTIMER=15
declare -A pid_array

if [[ -z "${MLAT_CONFIG}" ]]
then
    echo "[$(date)][${APPNAME}] Warning: MLAT_CONFIG not defined - MLAT will be disabled."
    sleep infinity
fi

if [[ -z "${MLAT_USER}" ]] && [[ -z "${UUID}" ]]
then
    echo "[$(date)][${APPNAME}] ERROR: either UUID or MLAT_USER must be defined - MLAT will be disabled."
    sleep infinity
fi

# MLAT_CONFIG has the following format:
# MLAT_CONFIG=mlatserver_1,mlatserver_port_1[,results_port_1[,extra_params_1]];mlatserver_2,mlatserver_port_2[,results_port_2[,extra_params_2]] etc

# parse MLAT_CONFIG string into mlat_configs array
readarray -td ";" mlat_configs < <(printf '%s' "${MLAT_CONFIG// /}")

# Now loop through the MLAT_CONFIG items and start up an Mlat_client for each of them:
for instance in "${mlat_configs[@]}"
do
    [[ -z "${instance}" ]] && continue || true
    # put individual params into the $params array:
    readarray -td "," params < <(printf '%s' "${instance}")

    # Check if the params array has values for the mandatory elements:
    if [[ -z "${params[0]}" ]] || [[ -z "${params[1]}" ]]
    then
        echo "[$(date)][${APPNAME}] ERROR -- MLAT_CONFIG is malformed: \"${instance}\". Stopping MLAT execution."
         # shellcheck disable=SC2046
        kill $(ps -s $$ -o pid=)   
        sleep infinity
    fi

    # Build the MLAT parameter string:
    MLAT_PARAM=(--input-type "${MLAT_INPUT_TYPE}")
    MLAT_PARAM+=(--input-connect localhost:30005)
    MLAT_PARAM+=(--server "${params[0]}:${params[1]}")
    MLAT_PARAM+=(--lat "${READSB_LAT}")
    MLAT_PARAM+=(--lon "${READSB_LON}")
    MLAT_PARAM+=(--alt "${READSB_ALT}")
    # [[ -n "${UUID}" ]] && MLAT_PARAM+=(--user "${UUID}") || MLAT_PARAM+=(--user "${MLAT_USER}")
    [[ -n "${MLAT_USER}" ]] && MLAT_PARAM+=(--user "${MLAT_USER}") || MLAT_PARAM+=(--user "${UUID}")
    [[ -n "${params[2]}" ]] && MLAT_PARAM+=("--results beast,listen,${params[2]}") || true
    [[ -n "${params[3]}" ]] && MLAT_PARAM+=("${params[3]}") || true

    # shellcheck disable=SC2048,SC2086
    execstring="$(echo ${MLAT_CMD} ${MLAT_PARAM[*]} | xargs)"

    # run this Mlat_client instance in the background:
    echo  "[$(date)][${APPNAME}] starting: ${MLAT_CMD} ${MLAT_PARAM[*]}"
    { exec ${execstring} 2>&1 1>/dev/null | stdbuf -o0 awk -v app="${APPNAME}" -v inst="${params[0]}" '{print "[" strftime("%Y/%m/%d %H:%M:%S", systime()) "][" app "][" inst "] " $0}'; } &
    pid_array[$!]="${MLAT_PARAM[*]}"
    sleep 5
done

# Now iterate over all MLAT-client instances and check if they are still running:
while true
do
    for mlat_pid in "${!pid_array[@]}"
    do
        if ! kill -0 "${mlat_pid}" >/dev/null 2>&1
        then
            # it exited - let's restart:
            sleep "${RESTARTTIMER}"
            echo  "[$(date)][${APPNAME}] MLAT_Client $(awk '{print $6}' <<< "${pid_array[$mlat_pid]}") exited. Attempting to restart."
            # shellcheck disable=SC2086
            execstring="$(echo ${MLAT_CMD} ${pid_array[$mlat_pid]} | xargs)"
            { exec ${execstring} 2>&1 1>/dev/null | stdbuf -o0 awk -v app="${APPNAME}" -v inst="$(awk '{split($6,x,":"); print x[1]}' <<< "${pid_array[$mlat_pid]}")" '{print "[" strftime("%Y/%m/%d %H:%M:%S", systime()) "][" app "][" inst "] " $0}'; } &
            pid_array[$!]="${pid_array[${mlat_pid}]}"
            unset "pid_array[${mlat_pid}]"
        fi
    done
    sleep 10
done