gistfile1.js

(function (_, q, harCapturer, aws, spawn) {
    "use strict";
    harCapturer.setVerbose(true);

    var gcArgs = ["--remote-debugging-port=9222", "--enable-benchmarking", "--enable-net-benchmarking"],
        options = { cwd: undefined, env: process.env },
        google = spawn("google-chrome", gcArgs, options),
        queueUri = process.env.QUEUE_URI,
        shouldDebug = process.env.DEBUG || false,
        bucketName = "blitz-project-10k",
        cfg = {
            accessKeyId: process.env.AWS_ACCESS_KEY,
            secretAccessKey: process.env.AWS_SECRET_KEY,
            region: "us-east-1"
        },
        awsConfig = aws.config.update(cfg),
        s3Params = { Bucket: bucketName},
        s3 = new aws.S3({params: s3Params}),
        sqs = new aws.SQS(),
        backoff = {};

    function cleanup() {
        google.kill("SIGKILL");
        process.exit(0);
    }

    process
        .on("SIGINT", cleanup)
        .on("SIGTERM", cleanup)
        .on("SIGQUIT", cleanup);

    function debug(msg) {
        if (shouldDebug) {
            console.log(msg);
        }
    }

    function getSiteMessage() {
        debug("Polling for site");

        var df = q.defer(),
            params = {
                QueueUrl: queueUri,
                MaxNumberOfMessages: 1,
                VisibilityTimeout: 120,
                WaitTimeSeconds: 20
            };

        sqs.receiveMessage(params, function (err, data) {
            if (err) {
                debug("An error has occurred:" + err);
                df.reject(err);
            }

            if (!data || !data.Messages || _.isEmpty(data.Messages)) {
                df.reject("No messages found.");
            } else {
                df.resolve(_.merge({}, {
                    site: _.first(data.Messages).Body,
                    receiptHandle: _.first(data.Messages).ReceiptHandle
                }));
            }
        });

        return df.promise;
    }

    function getBackoffTimeout(site) {
        backoff[site] = (backoff[site] ? backoff[site] * 1.5 : undefined) || 60000;
        backoff[site] = backoff[site] > 120000 ? 120000 : backoff[site];
        return backoff[site];
    }

    function captureHAR(state) {
        var df = q.defer(),
            chromeHandle = harCapturer.load(state.site),
            delay = _.delay(function () {
                df.reject("Timeout occured on " + state.site + " at " + backoff[state.site] + "s");
            }, getBackoffTimeout(state.site));

        debug("Running HAR capture on " + state.site);

        chromeHandle.on("error", function () {
            df.reject("Error occured in Chrome");
        });

        chromeHandle.on("end", function (har) {
            clearTimeout(delay);
            delete backoff[state.site];
            df.resolve(_.merge({}, state, {har: har}));
        });

        return df.promise;
    }

    function saveResultToS3(state) {
        var df = q.defer(),
            today = new Date(),
            year = today.getFullYear(),
            month = today.getMonth(),
            day = today.getDate(),
            formatted = [year, month, day].join("-"),
            fileName = [state.site, ".har"].join(""),
            keyName = [formatted, fileName].join("/"),
            bodyContent = JSON.stringify(state.har),
            putArgs = { Key: keyName, Body: bodyContent };

        s3.putObject(putArgs, function (err, data) {
            if (err) {
                df.reject(err);
            } else {
                debug("Writing " + state.site + " to bucket:" + bucketName);
                df.resolve(_.merge({}, state, { putResult: true, putData: data }));
            }
        });

        return df.promise;
    }

    function removeMessage(state) {
        var df = q.defer(),
            params = {
                QueueUrl: queueUri,
                ReceiptHandle: state.receiptHandle
            };

        sqs.deleteMessage(params, function (err, data) {
            if (err) {
                df.reject(err);
            } else {
                debug("Dequeueing message for " + state.site);
                df.resolve(_.merge({}, state, {dequeueData: data}));
            }
        });

        return df.promise;
    }

    function startPolling() {
        getSiteMessage()
            .then(captureHAR)
            .then(saveResultToS3)
            .then(removeMessage)
            .fail(function (err) {
                console.log("Chrome crashed: " + err);
                google.kill("SIGKILL");
                google = spawn("google-chrome", gcArgs, options);
            })
            .finally(function () {
                _.delay(startPolling, 2000);
            });
    }

    _.delay(startPolling, 2000);
}(
    require("lodash"),
    require("q"),
    require("chrome-har-capturer"),
    require("aws-sdk"),
    require("child_process").spawn
));