Interview on DevOps

From time to time, I get the opportunity to talk to industry reporters about agile and DevOps. Today, I was interviewed via email for the first time, which turned out pretty interesting. Here are the questions and answers from that interview.

Please briefly describe how the company is using DevOps, including when it began, which DevOps tools and for which types of projects.

We see DevOps as a culture that encompasses people, practices, tools and philosophy. In that sense, it has become central to everything we do to develop, maintain and operate our e-commerce sites for,, and, of course, Home Depot custom window coverings. Infrastructure is code that evolves in concert with our other software components. DevOps happens inside our agile development teams and often draws in specialized resources from our operations group. It also happens inside our infrastructure group and often draws in developers. It’s part of our DNA.

The tools aspect of it is pretty standard stuff. We use Git and GitHub for source control. All our application and infrastructure code is there. Puppet helps us with rolling out and managing servers. Our backends are mostly .NET so we use Octopus Deploy to help with rolling our code. TeamCity is in the middle of our development process and code there is used to expose deployments and tie them together with builds. Logs are mostly managed by Splunk though we’ve played with an ELK stack for this as well. Nagios is used for infrastructure monitoring. NewRelic is our app monitoring tool and we depend on it to alert us to problems with the user experience. All our alerts get fed into Pager Duty for escalation management. We’ve been experimenting with Consul for discovery and config.  We’re also experimenting with Docker. What’s holding us back there is .NET on Windows. Of course, that story is changing with .NET Core and Windows 2016 on the horizon so we have high hopes for Docker as a next step.

What were the business drivers for deploying DevOps?

Agile drove our adoption of DevOps. Our adoption of agile was driven by our organization’s culture more than anything else. One of our key values is “experiment without fear of failure”. Another is “improve continuously”. Over the years, our whole IT process had gotten into that uncomfortable place where limited resources lead to a difficult relationship with the rest of the business. They saw us as standing in the way of all the cool experimentation and improvement they wanted to do. Agile helped us break down the walls that had developed and form a true partnership for innovation. DevOps is a necessary part of the agile process. How can you innovate constantly if deployment requires an over-the-wall handoff and lots of manual intervention to get done? If operations and infrastructure are not intimately involved in the process, how can you support and manage it once it gets into production?

What benefits has the company seen from DevOps? 

DevOps enables agile, which allows us to continuously improve. It’s a big part of how we were able to deliver on all the promises of our new e-commerce platform, which lead directly to the acquisition by Home Depot. It has allowed us to continue to innovate and thrive inside a Fortune 50 corporation and take on new challenges to help drive innovation outside of the custom window coverings business.  DevOps is like oxygen for the agile process. Without it, it’s very possible that we would have ended up with “agile in name only” where agile terminology is used but nothing really changes and the organization doesn’t see the kind of exponential increase in innovation that we’re benefited from here.

Any challenges of deploying and using DevOps, and how were they addressed?

Our biggest challenges revolve around security and compliance especially now that we are part of one of the largest retailers in the world. We’re still learning how to deal with all that when it comes to sharing responsibility for deployment and infrastructure between developers, infrastructure and operations engineers. We’re constantly tempted to solve these problems with handoffs and work hard to avoid that. Now that we have trust across all the impacted groups it’s much easier to work through them and come up with ways to address compliance without undermining the velocity of innovation.

Rabbit Operations 0.9.0 Released

This version is a minor maintenance release that includes the ability to set a different expiration time for error messages to give you more time to analyze them and possibly replay them. It also includes an upgrade to the latest stable release of RavenDB.  Check out the project website for more information.

The next release, 0.10.0, will include some major improvements including a new GUI and the ability to view and analyze statistics collected from all messages.  You can check out the plan on our Trello board.

Rabbit Operations Version 0.8.0 Released

This is a minor release but it contains one significant goodie: The details dialog for errors now has a section that displays a nicely formatted stack dump. Here are the complete release notes:

  • Nicely formatted stack dump shown on details view of error message
  • Ability to view queue stats as a gauge
  • Improve performance of search screen especially when bringing back large sets of large messages
  • BUG FIX: Small memory leak in poller due to RavenDB profiler stats
  • BUG FIX: Retry to overcome RavenDB transients under high loads when there are more than 40 active queue pollers

Check it out the Project Site for more details.

RabbitOperations Project Launched

An early preview release of my new open source project, RabbitOperations, is now available at The idea is to provide some tools for managing real-world applications that use RabbitMQ. It will support popular message buses like NServiceBus and Rebus with error replay, audit & error logging, sophisticated search capabilities and likely an integration with NewRelic to log stats about queue lengths etc. This very early release lacks a UI and is only suitable for experimentation and potential contributors.

ASP.NET MVC Attribute Supporting SSL Terminated at Amazon Elastic Load Balancer

In my last post, I described an ASP.NET Web Api RequireHttps attribute that supports SSL terminated at a load balancer like Amazon’s ELB.  Here’s a RequireHttps attribute for ASP.NET MVC with load balancer support:

using System;
using System.Configuration;
using System.Web.Mvc;
using System.Web;
using System.Collections.Generic;

namespace MvcHelpers
    public class RequireHttpsSupportsLBAttibute : RequireHttpsAttribute
        public override void OnAuthorization(AuthorizationContext filterContext)
            if (filterContext.HttpContext.Request.IsSecureConnectionConsideringLoadBalancer()) return;


    public static class HttpRequestBaseHelper
        public static bool IsSecureConnectionConsideringLoadBalancer(this HttpRequestBase request)
            return request.IsSecureConnection || LoadBalancerSecured(request);

        public static bool LoadBalancerSecured(HttpRequestBase request)
            if (string.Equals(request.Headers["X-Forwarded-Proto"],
                return true;

            return false;

ASP.NET Web API 2 RequireSsl Attribute With Support For Terminating SSL At Load Balancer

Most modern load balancers, including Amazon’s Elastic Load Balancer (ELB), allow you to configure them to handle SSL. Although they can forward the request to your web nodes using SSL, it is more efficient to offload the SSL processing to the load balancer and forward requests from there to your web servers using plain HTTP on port 80. Load balancers that support offloading SSL generally inject a “X-Forwarded-Proto” header into the request with the value “http” or “https” to indicate the protocol of the original request. This approach is quite secure as the load balancer typically replaces any “X-Forwarded-Proto” header present in the original request. This is true for ELB.

You can use this header in ASP.NET Web API to make sure a request is secure. For example, here’s an attribute you can put on any controller or controller method to require SSL. It supports SSL terminated at the load balancer as well as plain old SSL straight to the server:

using System;
using System.Configuration;
using System.Linq;
using System.Net.Http;
using System.Web.Http.Controllers;
using System.Web.Http.Filters;

namespace AspNetApiHelpers
    public class RequireHttpsAttribute : AuthorizationFilterAttribute
        public override void OnAuthorization(HttpActionContext actionContext)
            if (actionContext.Request.RequestUri.Scheme != Uri.UriSchemeHttps && !IsForwardedSsl(actionContext))
                actionContext.Response = new HttpResponseMessage(System.Net.HttpStatusCode.Forbidden)
                    ReasonPhrase = "HTTPS Required"

        private static bool IsForwardedSsl(HttpActionContext actionContext)
            var xForwardedProto = actionContext.Request.Headers.FirstOrDefault(x => x.Key == "X-Forwarded-Proto");
            var forwardedSsl = xForwardedProto.Value != null &&
                xForwardedProto.Value.Any(x => string.Equals(x, "https", StringComparison.InvariantCultureIgnoreCase));
            return forwardedSsl;

Configuring a Raspberry Pi to Talk to Delcom USB With Node.js

Took a little digging, but I have Node.js 0.10.24 and Node-Hid successfully installed and talking to my Delcom USB indicator.  I wanted to take a minute to document the steps I took.  Before following the steps in this article, make sure you have your Raspberry Pi hooked up to the network.

Getting the OS Ready

Start by updating all your packages:

sudo apt-get update
sudo apt-get dist-upgrade

You will need a couple of additional packages required by node-hid, a node library used to communicate with USB HID devices like the Delcom USB Indicator:

sudo apt-get install libudev-dev libusb-1.0-0-dev

Node.js Install

As least as I write this you cannot get Node.js 0.10.x using apt-get. Instead, you have to install it yourself. Here’s the steps I used for node 0.10.24:

sudo mkdir /opt/node
tar xvzf node-v0.10.24-linux-arm-pi.tar.gz
sudo cp -r node-v0.10.24-linux-arm-pi/* /opt/node

You’ll also have to put node into your path and set NODE_JS_HOME by editing your profile. Open up the profile:

sudo nano /etc/profile

Put the following right before you see “export PATH”:


Once you reboot, you can verify the node installation by issuing the following command:

node -v

It should print out v0.10.24 on your console.

Node-Hid and Test Project

Now it’s time to create a little node project to test things out. This example will set things up in a directory called ~/nodetest:

mkdir ~/nodetest
cd ~/nodetest
npm install node-hid

You can then use nano to create a js file to execute with node:

nano test.js

Here’s the code:

var hid = require('node-hid');

var devices = hid.devices();


Once you plug in the Delcom device, you can run the app to find it as follows:

node test.js

You should see output like this:

[ { vendorId: 4037,
    productId: 45184,
    path: '0001:0005:00',
    release: 32,
    interface: 0 } ]

If you have multiple USB HID devices attached, they will appear in the list as well. The one with the vendorId given above is the Delcom device.

One More Thing

I prefer to write code on my Mac using Webstorm.  I get access to my Raspberry Pi console using ssh and transfer files with help from the netatalk AFP client installed as follows:

sudo apt-get install netatalk

Rolled Up My Sleeves and Got Raspberry Pi Booting

So it appears that my mistake was paying a little extra for the kit.  I reformatted the SD card, downloaded the new out of the box software (NOOBS), copied it onto the SD card, powered up the Pi and about 30 minutes later it was booting just fine into Raspbian Linux.  I’ve got to pick up a supported USB WiFi device today so I can get it onto the network.  I can then start testing some code.  Fun!

I Hope I Like Raspberry Pi

Recently, we spun up a new team at to work on a critical add-on called Blinds Tracker for both our production web platform and our soon-to-be-released Autobahn platform.  In addition to being the Product Owner I am also handling DevOps tasks.  One of the fun things I did for the Autobahn team was to put up a physical build light from Delcom that glows green when all is well, blinks blue when a build is underway and flashes red when the build is broken.  I built the necessary utility in .NET and so the light has to be plugged into a Windows laptop that sits off in a corner polling TeamCity from time to time.

Once I had the new project building on TeamCity I decided I wanted a build light for it too.  Besides being a stop on the company tour, it provides a nice visual indication of the project’s health for me, the other team members and stakeholders that can see it from across our open floor plan office.  It’s a different team so I didn’t want to share the Autobahn build light; When it turns red, it should be because Autobahn is broken.  The teams don’t sit in the same area so I can’t really plug a second light into the existing laptop either.

Sounds simple right?  All I have to do is purchase a Delcom visual indicator, grab an old Windows laptop, install my utility and hook it up.  Unfortunately, we don’t have any unused laptops around so I’d have to requisition one.  I jokingly discussed it with one of the developers on the team and he said, “well, you’ve been working with Node.js.  Why don’t you just get it up on a Raspberry Pi.”

So in typical geek fashion I set out to save a few hundred bucks by spending some indeterminate hours of my personal time putting together a Node.js build light application for Raspberry Pi.  I’m lazy so I ordered the Raspberry Pi B (512MB Ram, 2 USB Ports, HDMI and Ethernet), a USB Wifi dongle, a micro USB power supply, an 8gb SD card and a clear case from Amazon.  I also ordered a tri-color USB visual indicator from Delcom.  It will all arrive at the house early next week.  In the meanwhile, I’m going to start building a Node.js website to configure settings and a TeamCity poller that will eventually drive the light.  I think I can get it setup to work on any platform that supports HID so it will likely work on various flavors of Linux, Mac and PC in addition to the Raspbian Linux distribution for Raspberry Pi.  It will be an open source project and I’ll put the source up on Github.  Should be fun.