slack-police.js

var url = require('url');
var https = require('https');
var querystring = require('querystring');

var webhookID = 'YOUR/WEBHOOK/integration-id';
var webhookURLBase = 'https://hooks.slack.com/services/';
var webhookURL = [webhookURLBase, webhookID].join('');

var slashCommandToken = 'your-slash-command-token';

var postPayload = function (payload, callback) {
    var json = JSON.stringify(payload);

    var body = json;
    var options = url.parse(webhookURL);
    options.method = 'POST';
    options.headers = {
        'Content-Type': 'application/json',
        'Content-Length': Buffer.byteLength(body),
    };

    var postReq = https.request(options, function (res) {
        var chunks = [];
        res.setEncoding('utf8');
        res.on('data', function (chunk) {
            return chunks.push(chunk);
        });
        res.on('end', function () {
            var body = chunks.join('');
            if (callback) {
                callback({
                    body: body,
                    statusCode: res.statusCode,
                    statusMessage: res.statusMessage
                });
            }
        });
        return res;
    });

    postReq.write(body);
    postReq.end();
};

var textForParams = function (params) {
    if (params.text && params.text.indexOf(' ') != -1) {
        return params.text;
    } else {
        var intro = "Okay folks, let's move this conversation";
        var to = (params.text ? ('#' + params.text).replace(/##/, '#') : 'elsewhere');

        return [intro, ' ', to, '.'].join('');
    }
};

var payloadForParams = function (params) {
    return {
        channel: ['#', params.channel_name].join(''),
        text: textForParams(params),
        link_names: 1,
        mrkdwn: true
    };
};

var processEvent = function (event, context) {
    var params = querystring.parse(event.postBody);
    
    if (params.token !== slashCommandToken) {
      context.fail(new Error('Invalid Slash Command token.'));
      return;
    }
    
    postPayload(payloadForParams(params), function (response) {
        if (response.statusCode < 400) {
            console.info('Message posted successfully');
            context.succeed();
        } else if (response.statusCode < 500) {
            console.error("Error posting message to Slack API: " + response.statusCode + " - " + response.statusMessage);
            context.succeed();  // Don't retry because the error is due to a problem with the request
        } else {
            // Let Lambda retry
            var msg = "Server error when processing message: " + response.statusCode + " - " + response.statusMessage
            context.fail(new Error(msg));
        }
    });
};

exports.handler = function (event, context) {
    try {
        processEvent(event, context);
    } catch (e) {
        context.fail(e);
    }
};