Report UDP network statistics (#1176)

* Report UDP network statistics

Fixes #1093

* Address review comments

* Address additional review comments

* Fix shellcheck errors

scripts/net-stats.sh

@@ -0,0 +1,49 @@
+#!/bin/bash -e
+#
+# Reports network statistics
+#
+
+[[ $(uname) == Linux ]] || exit 0
+
+cd "$(dirname "$0")"
+
+# shellcheck source=scripts/configure-metrics.sh
+source configure-metrics.sh
+
+packets_received=0
+packets_received_diff=0
+receive_errors=0
+receive_errors_diff=0
+rcvbuf_errors=0
+rcvbuf_errors_diff=0
+
+update_netstat() {
+  declare net_stat
+  net_stat=$(netstat -suna)
+
+  declare stats
+  stats=$(echo "$net_stat" | awk 'BEGIN {tmp_var = 0} /packets received/ {tmp_var = $1} END { print tmp_var }')
+  packets_received_diff=$((stats - packets_received))
+  packets_received="$stats"
+
+  stats=$(echo "$net_stat" | awk 'BEGIN {tmp_var = 0} /packet receive errors/ {tmp_var = $1} END { print tmp_var }')
+  receive_errors_diff=$((stats - receive_errors))
+  receive_errors="$stats"
+
+  stats=$(echo "$net_stat" | awk 'BEGIN {tmp_var = 0} /RcvbufErrors/ {tmp_var = $2} END { print tmp_var }')
+  rcvbuf_errors_diff=$((stats - rcvbuf_errors))
+  rcvbuf_errors="$stats"
+}
+
+update_netstat
+
+while true; do
+  update_netstat
+  report="packets_received=$packets_received_diff,receive_errors=$receive_errors_diff,rcvbuf_errors=$rcvbuf_errors_diff"
+
+  echo "$report"
+  ./metrics-write-datapoint.sh "net-stats,hostname=$HOSTNAME $report"
+  sleep 60
+done
+
+exit 1