A ucode script for collecting ethernet statistics and sending to statsd, running on OpenWrt

ethstat.u

#!/usr/bin/ucode

// require package ucode-mod-fs, ucode-mod-uloop, ucode-mod-socket
import * as fs from 'fs';
import * as uloop from 'uloop';
import * as socket from 'socket';

const CONFIG = {
    host: "192.168.1.230",
    port: 8125,
    interval: 1000,
    prefix: "openwrt.ethstat",
    interfaces: ["wan", "lan2", "lan3", "lan4"],
    metrics: {
        "TxBytes": "bytes",
        "RxBytes": "bytes",
    }
};

const sock = socket.create(socket.AF_INET, socket.SOCK_DGRAM);
if (!sock) {
    print("Error: Unable to create socket\n");
    exit(1);
}
if (!sock.connect(CONFIG.host, CONFIG.port)) {
    print(`Error: Unable to connect to ${CONFIG.host}:${CONFIG.port}\n`);
    exit(1);
}

let cache = {};

function get_ethtool_stats(iface) {
    let p = fs.popen(`ethtool -S ${iface}`, "r");
    if (!p) return null;

    let stats = {};
    let line;

    while ((line = p.read("line")) != null) {
        let parts = split(line, ":");
        if (length(parts) == 2) {
            let key = trim(parts[0]);
            if (key in CONFIG.metrics) {
                stats[key] = +trim(parts[1]);
            }
        }
    }
    p.close();
    return stats;
}

function collect_and_send() {
    let data_point = [];

    for (let iface in CONFIG.interfaces) {
        let current_stats = get_ethtool_stats(iface);
        if (!current_stats) continue;

        if (!cache[iface]) cache[iface] = {};

        for (let key in current_stats) {
            let val = current_stats[key];
            let full_key = `${CONFIG.prefix}.${iface}.${key}`;
            let unit = CONFIG.metrics[key];

            push(data_point, `${full_key}:${val}|g|#units:${unit}`);

            if (exists(cache[iface], key)) {
                let delta = val - cache[iface][key];
                if (unit == "bytes") {
                    delta *= 8;
                    unit = "bit";
                }
                let rate = delta * 1000 / CONFIG.interval;
                if (rate >= 0) {
                    push(data_point, `${full_key}Rate:${rate}|g|#units:${unit}/s`);
                }
            }

            cache[iface][key] = val;
        }
    }

    if (length(data_point) > 0) {
        let buffer = join("\n", data_point);
        sock.send(buffer);
        // printf(`Length: ${length(buffer)}\n`);
        // printf(`Buffer:\n${buffer}\n\n`);
    }
}

uloop.init();
uloop.interval(CONFIG.interval, collect_and_send);
uloop.run();

root-etc-init.d-ethstat

#!/bin/sh /etc/rc.common

START=99
USE_PROCD=1

start_service() {
    procd_open_instance
    procd_set_param command /root/ethstat.u
    procd_set_param respawn ${respawn_threshold:-3600} ${respawn_timeout:-5} ${respawn_retry:-5}
    procd_set_param stdout 1
    procd_set_param stderr 1
    procd_close_instance
}