aws lambda function to post slack

slack.js

var aws = require('aws-sdk');
var kms = new aws.KMS({ region: 'us-east-1' });

var encrypted_slack_hook = 'CiD0R0tv46w7LNpO0GlZpLfZk2O0Oy66IF83rG6olDY7yBK0AQEBAgB49EdL\nb+OsOyzaTtBpWaS32ZNjtDsuuiBfN6xuqJQ2O8gAAACLMIGIBgkqhkiG9w0B\nBwagezB5AgEAMHQGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMWk63DEyG\ne+3v8STHAgEQgEfYBkRk3roZCsirvAsWbPhGN15PqfGA58M/Vh3ZqHFFCkf9\nceSWkIii4SZz3tlpHu3AXjk3x2AWTCMmVTX2EUkawF5sTNsNZA==\n';

//console.log('Loading function');
exports.handler = function(event, context) {
    console.log('Received event:', JSON.stringify(event, null, 2));

    var p = {CiphertextBlob: new Buffer(encrypted_slack_hook, 'base64')};
    kms.decrypt(p, function(err, data) {
        if (err) context.fail(err);
        else {
            var slack_hook = data.Plaintext.toString();
            //console.log('slack_hook: ' + slack_hook);
            
		    var http = require('https');
		    var postData = JSON.stringify({
		        username: event.username || 'lambda',
		        icon_url: event.icon_url || 'https://raw.githubusercontent.com/donnemartin/dev-setup-resources/master/res/aws_lambda.png',
		        text: event.text,
		        channel: event.channel || '#test'
		    });
		    var headers = {
		        'Content-Type': 'application/json',
		        'Content-Length': postData.length
		    };
		    var options = {
		        host: 'hooks.slack.com',
		        port: 443,
		        path: '/services/' + slack_hook,
		        headers: headers,
		        method: 'POST'
		    };

		    callback = function(response) {
		        var status = response.statusCode;
		        console.log(status);

		        var str = '';
		        var msg = '';
		        response.on('data', function (chunk) {
		                str += chunk;
		        });

		        response.on('end', function () {
		                console.log(str);
		                if (status == 200){
		                    msg = 'Successfully posted to Slack!';
		                    console.log(msg);
		                    context.succeed(msg);
		                } else {
		                    msg = 'Failed to post to Slack...';
		                    console.log(msg);
		                    context.fail(msg);
		                }    
		        });
		        response.on('error', function(e) {
		            console.log('problem with req: ' + e.message);
		        });
		    };

		    var req = http.request(options, callback);
		    req.write(postData);
		    req.end();
		}
	});
};