systemd notify-compatible wrapper script to launch and monitor filebeat

filebeat_sd_notify_wrapper.sh

#!/usr/bin/env bash

CONNECT_TIMEOUT=${HTTP_CONNECT_TIMEOUT:-1}
HTTP_ADDR=${FILEBEAT_HTTP_ADDR:-http://localhost:5066/}
REPORT_TIME=$(($WATCHDOG_USEC / 2000000))
SD_NOTIFY=${SD_NOTIFY_PATH:-/bin/systemd-notify}

set -euo pipefail

function watchdog() {
    READY=0
    sleep ${REPORT_TIME}

    while true ; do
        info=$(curl -fs --connect-timeout "${CONNECT_TIMEOUT}" "${HTTP_ADDR}")
        beat=$(echo "${info}" | jq -r .beat)
        version=$(echo "${info}" | jq -r .version)
        if [[ $? == 0 ]] ; then
            if [[ $READY == 0 ]] ; then
                "${SD_NOTIFY}" --ready
                READY=1
            fi

            "${SD_NOTIFY}" WATCHDOG=1
            "${SD_NOTIFY}" STATUS="${beat} running v${version}"
        else
            "${SD_NOTIFY}" WATCHDOG=trigger
            "${SD_NOTIFY}" STATUS=Beat not responding
            exit 1
        fi

        sleep ${REPORT_TIME}
    done
}

watchdog &

exec /usr/share/filebeat/bin/filebeat "$@"