Simple bash scripts to collect connection statistics to a remote host (ping latency and wifi signal strength) and generate graphs over time. I couldn't find any simple solutions for this task--only heavyweight frameworks such as smokeping/vaping or prometheus or other cloud-centric monitoring solutions.

connection_monitor.sh

#!/bin/bash

# Monitor connection statistics (latency + wifi signal strength) continuously.
# Stores timeseries data in RRDTool

set -e

WIFI_DEV="wlan0"
MAC='aa:bb:cc:dd:ee:ff'
PING_HOST='192.168.1.10'
DB='/home/u/connection_stats.rrd'
UPDATE_INTERVAL=5  # Loop every 5 seconds

get_station_info() {
  unset signal
  iw dev ${WIFI_DEV} station dump | grep "Station ${MAC}" > /dev/null || station_missing=true;
  if [[ "$station_missing" = true ]]; then
    echo "Wifi station missing: ${MAC}"
    return
  fi

  # TODO: can extract other metrics here: "failed/retries/etc..."
  signal=$(iw dev ${WIFI_DEV} station get $MAC | grep 'signal:' | awk '{print $2}')
}

get_ping_info() {
  ping_time=$(fping -u -C1 -p1000 -e $PING_HOST 2>&1 | sed -e 's/.*: //')
}

while :; do
  # This is rather verbose--especially 'updatev' below (rather than 'update')
  # Assumes this is streamed to some log system with rotation (e.g. systemd)
  echo '*****'
  echo "Time: $(date +%H:%M:%S)"
  get_station_info
  echo "Signal: ${signal}"
  get_ping_info
  echo "Ping result: ${ping_time}"
  if [ "$ping_time" = "-" ]; then
    # U=no value for this time point
    ping_time='U'
  fi
  # N=use current time
  echo rrdtool updatev ${DB} N:${signal}:${ping_time}
  rrdtool updatev ${DB} N:${signal}:${ping_time}
  # sleep until the next X seconds are full
  perl -e "sleep ${UPDATE_INTERVAL} - time % ${UPDATE_INTERVAL}"
done

exit 0;

# The following command creates the RRD file initially and defines
# the timeseries collection parameters.
# Store every 5 seconds
# Every 5 seconds (5s*1) for the last 6 hours
# Every 5 minutes (5s*12*5) for the 30 days (720 hours=43200 minutes)
# Total file size: 200K
rrdtool create connection_stats.rrd \
  --step 5 \
  DS:signal:GAUGE:10:-100:-10 \
  DS:latency:GAUGE:10:0:U \
  RRA:AVERAGE:0.5:1:4320 \
  RRA:AVERAGE:0.5:60:8760

graph_connection_stats.sh

#!/bin/bash

# Periodically generate graphs from data collected from connection_monitor.sh.
# Push them to a GCS bucket for public serving.

set -e

DB='/home/u/connection_stats.rrd'
DIR='/home/u/graphs'
GCS_FILE='gs://mybucket/connection_stats.png'
UPDATE_INTERVAL=300  # Every 5 minutes

make_graph() {
  period=$1
  start=$(date +%s -d "-${period}")
  echo $(date -d "-${period}")
  rrdtool graphv ${DIR}/connection-latency-${period}.png \
    --title="Latency\n(${period}) lower=better" \
    --start=${start} \
    DEF:latency=${DB}:latency:AVERAGE \
    LINE1:latency#6699CC:'latency (ms)'

  rrdtool graphv ${DIR}/connection-signal-${period}.png \
    --title="Wifi Signal\n(${period}) higher=better" \
    --start=${start} \
    DEF:signal=${DB}:signal:AVERAGE \
    LINE1:signal#ff0000:'signal (db)' \

  gm convert \
    ${DIR}/connection-latency-${period}.png \
    ${DIR}/connection-signal-${period}.png \
    -append \
    ${DIR}/connection-${period}.png
}

make_graphs() {
  make_graph 10min
  make_graph 2hour
  make_graph 24hour
  make_graph 168hour
  gm convert \
    ${DIR}/connection-10min.png \
    ${DIR}/connection-2hour.png \
    ${DIR}/connection-24hour.png \
    ${DIR}/connection-168hour.png \
    +append \
    ${DIR}/connection.png
}

upload_to_cloud() {
  # Pricing:
  # 2 operations * 12/hr * 24 hr/day * 30 day/mo = 17k op/mo
  # 17 kop/mo * 0.005 $/kop = 0.085 $/mo  (cheap :P)
  echo "Uploading to GCS"
  gcloud storage cp ${DIR}/connection.png ${GCS_FILE}
  echo "Updating GCS access + cache parameters"
  gcloud storage objects update ${GCS_FILE} \
    --add-acl-grant=entity=AllUsers,role=READER \
    --cache-control=no-cache
}

while :; do
  echo '*****'
  echo "Time: $(date +%H:%M:%S)"
  make_graphs
  upload_to_cloud
  # sleep until the next X seconds are full
  perl -e "sleep ${UPDATE_INTERVAL} - time % ${UPDATE_INTERVAL}"
done