website response speed monitor with collectd

curl.conf

# file: curl.conf
LoadPlugin curl
<Plugin curl>
    <Page "bing_cn">
        URL "https://cn.bing.com"
        MeasureResponseTime true
        MeasureResponseCode true
        <Statistics>
            TotalTime true
            NamelookupTime true
            SpeedDownload true
        </Statistics>
    </Page>
</Plugin>

exec.conf

# file: website_speed.conf
LoadPlugin exec
<Plugin exec>
    Exec "nobody:nogroup"  "/etc/collectd/collectd.conf.d/website_speed.sh"
</Plugin>

# file: /etc/collectd/collectd.conf.d/website_speed.sh
#!/usr/bin/env bash
# set -o pipefail

# See https://starbeamrainbowlabs.com/blog/article.php?article=posts/361-Monitoring-Http-Response-Times-Collectd.html
# Variables:
#   COLLECTD_INTERVAL   Interval at which to collect data
#   COLLECTD_HOSTNAME   The hostname of the local machine
HOSTNAME="${COLLECTD_HOSTNAME:-localhost}"
INTERVAL="${COLLECTD_INTERVAL:-60}"

declare -A targets=(
    ["bing_en"]="https://www2.bing.com"
    ["bing_cn"]="https://cn.bing.com"
    ["google"]="https://www.google.com/ncr"
    ["facebook"]="https://www.facebook.com"
    ["youtube"]="https://www.youtube.com"
)

# Pure-bash alternative to sleep.
# Source: https://blog.dhampir.no/content/sleeping-without-a-subprocess-in-bash-and-how-to-sleep-forever
snore() {
    local IFS;
    [[ -n "${_snore_fd:-}" ]] || exec {_snore_fd}<> <(:);
    read ${1:+-t "$1"} -u $_snore_fd || :;
}

function check_target() {
  target_name="$1"
  target_url="$2"
  readarray -t result < <(curl -sS -o /dev/null -w "%{http_code}\n%{time_namelookup}\n%{time_connect}\n%{time_total}\n%{speed_download}" "${target_url}")
  echo "PUTVAL \"${HOSTNAME}/website_speed/gauge-${target_name}-http_code\" interval=${INTERVAL} N:${result[0]}"
  echo "PUTVAL \"${HOSTNAME}/website_speed/gauge-${target_name}-time_namelookup\" interval=${INTERVAL} N:${result[1]}"
  echo "PUTVAL \"${HOSTNAME}/website_speed/gauge-${target_name}-time_connect\" interval=${INTERVAL} N:${result[2]}"
  echo "PUTVAL \"${HOSTNAME}/website_speed/gauge-${target_name}-time_total\" interval=${INTERVAL} N:${result[3]}"
  echo "PUTVAL \"${HOSTNAME}/website_speed/gauge-${target_name}-speed_download\" interval=${INTERVAL} N:${result[4]}"
}

while :; do
     for target in "${!targets[@]}"; do
       check_target "${target}" "${targets[${target}]}"
     done
     snore "${INTERVAL}";
done