metricsHandler.js

const { createCall } = require('bitcoind-client');
const { register } = require('prom-client');
require('isomorphic-fetch');
const {
    bestBlockIndexMetric,
    bestBlockTimeMetric,
    difficultyMetric,
    walletVersionMetric,
    walletBalanceMetric,
    walletTransationsMetric,
    keyPoolOldestMetric,
    keyPoolSizeMetric,
    unlockedUntilMetric,
    transactionFeeMetric,
    addressBalanceMetric
} = require('./metrics');

const {
    ticker = 'BTC',
    rpcuser = 'rpcuser',
    rpcpassword = 'rpcpassword',
    rpchost = '127.0.0.1',
    rpcport = '8332',
    rpcscheme = 'http',
    walletMonitor = 'false'
} = process.env;

const call = createCall({
    rpcuser,
    rpcpassword,
    rpchost,
    rpcport,
    rpcscheme,
});

const parseBoolean = (value) => {
    if (typeof value === 'string') {
        value = value.trim().toLowerCase();
        return value === 'true' || value === '1';
    }
    return !!value;
};

const metricsHandler = (req, res) => {
    res.set('Content-Type', register.contentType);

    const promises = []
    if (parseBoolean(walletMonitor)) {
        const listUnspentPromise = call('listunspent')
            .then(transactions => transactions.reduce((balances, transaction) => {
                balances[transaction.address] = (balances[transaction.address] || 0) + transaction.amount;

                return balances;
            }, {}))
            .then(balances => Object
                .keys(balances)
                .forEach((address) => addressBalanceMetric.set({ address }, balances[address]))
            );
        const walletInfoPromise = call('getwalletinfo')
            .then(
                ({
                    unconfirmed_balance,
                    immature_balance,
                    balance,
                    walletversion,
                    txcount,
                    keypoolsize,
                    unlocked_until,
                    paytxfee,
                }) => {


                    walletVersionMetric.set({ ticker }, walletversion);
                    walletBalanceMetric.set({ status: 'unconfirmed' }, unconfirmed_balance);
                    walletBalanceMetric.set({ status: 'immature' }, immature_balance);
                    walletBalanceMetric.set({ status: 'confirmed' }, balance);
                    walletTransationsMetric.set(txcount);
                    unlockedUntilMetric.set(unlocked_until || 0);
                    keyPoolSizeMetric.set(keypoolsize);
                    transactionFeeMetric.set(paytxfee);
                }
            );
        promises.push(listUnspentPromise, walletInfoPromise);
    }

    const bestBlockPromise = call('getbestblockhash')
        .then(hash => call('getblock', hash))
        .then(bestBlockInfo => {
            bestBlockIndexMetric.set(bestBlockInfo.height);
            bestBlockTimeMetric.set(bestBlockInfo.time);
        });
    const difficultyPromise = call('getdifficulty')
        .then(difficulty => difficultyMetric.set(difficulty));

    promises.push(bestBlockPromise, difficultyPromise);
    Promise.all(promises)
        .then(() => res.end(register.metrics()))
        .catch((error) => {
            console.error(error);

            let code = 500;
            if (error.code === -28) {
                code = 503;
            } else if (error.code === 403) {
                code = 403;
            }

            return res.status(code).send(`# ${error.message}\n`)
        });
};

module.exports = metricsHandler;