QOS Logging Middleware for ActionHero

qosLog.js

const { Initializer, api } = require('actionhero');
const fs = require('fs');
const shortid = require('../lib/shortid');

const safeApiRequestId = params => (params.apiRequestId || shortid(20))
    .replace(/[^0-9a-zA-Z_-]/g, '')
    .substring(0, 64);

function instrumentAction(data) {
    const { action, params, response, connection } = data;

    // Create an api request ID if one wasn't on the record, and sanitize it
    const apiRequestId = safeApiRequestId(params);
    params.apiRequestId = apiRequestId;

    // Copy some fields to the response object for normal API calls
    response.action = action;
    response.apiRequestId = apiRequestId;
    response.serverTime = +new Date();

    data.actionQos = {
        action,
        apiRequestId,
        connectionId: (connection || {}).id,
        connectionType: (connection || {}).type,
        startTime: Date.now(),
        endTime: 0,
        execTime: 0,
        status: 0,
        headers: {},
        params: {},
    };

    // postProcessors are skipped on errors, so we set this ahead of time in case something throws.
    data.response.status = 'ERROR';
}

function reportQOS(data) {
    const { actionQos } = data;

    /* istanbul ignore next */
    if (!actionQos) {
        return;
    }

    actionQos.endTime = Date.now();
    actionQos.execTime = actionQos.endTime - actionQos.startTime;
    actionQos.status = ((data.connection || {}).rawConnection || {}).responseHttpCode || 200;

    // TODO: Add this record as a reportable metric maybe in CloudWatch?

    data.response.status = 'OK';
}

process.on('unhandledRejection', (reason, p) => console.log('Unhandled Rejection at:', p, 'reason:', reason));
process.on('uncaughtException', err => fs.writeSync(1, `Caught exception: ${err}\n`));

module.exports = class QOSLog extends Initializer {
    constructor() {
        super();

        this.name = 'QOSLog';
        this.loadPriority = 500;
        this.startPriority = 500;
        this.stopPriority = 500;
    }

    async initialize() {
        api.qosLog = QOSLog;
    }

    async start() {
        // Check incoming requests for authentication requirements
        api.actions.addMiddleware({
            name: 'Request Processing : QOS',
            global: true,
            priority: 500,
            preProcessor: instrumentAction,
            postProcessor: reportQOS
        });
    }

    async stop() {
        // TODO: Flush QOS metrics if necessary
    }
};