Continuous Deployment for Existing Software – Do it Now

I recently wrote about doing continuous deployment from day one with a software project that had pretty good test automation and (if I do say so myself) a somewhat modern and decent architecture.

I’ve recently transitioned to working on a fairly ambitious overhaul of an existing project that has been around for a few years. The software has already reached a (mostly) working steady state and is used every day by real customers.

The very first thing I did, ahead of making any functional changes, was automate the deployment system using essentially the same kind of test gauntlet and approach for zero-downtime deployments I was using at Victors United. I added some very basic test automation, starting from the top of the test automation food pyramid with a simple “is the web server able to execute code, connect to the database server, and return an ‘OK’ rsponse?” test. From there, I’ve working my way down, just getting around to writing my first “pure” unit test just today.

Only after I was confident that I could do zero-effort and zero-downtime deployments that

  1. Wouldn’t completely destroy the system (I had a test for that) and
  2. Could be rolled back very easily if something went screwy

did I make my first functional change to the software.

And then, I made the smallest functional changes that could work. I tested them locally, added some test automation around them, and then let the automatic deployment system do its magic.

A few years ago, I was interested in doing continuous deployment, but I felt that the level of test automation wasn’t good enough, I wanted to be at least at around 90%.  Now I think that the less test automation you have, the more important it is to start doing continuous deployment of tiny incremental changes right away.

If you are working on software that’s actually in use and are interested in doing continuous deployment someday, there’s no better someday than today. Seriously. Do it now. It will start making your life better almost immediately.


Always Be Shipping – Real-World Continuous Deployment

Have you ever edited code directly on a production server? I’ll admit that I have, years ago, before I knew better. It’s easy and fast and gets emergency fixes out there as quickly as possible. You get to know what works and what doesn’t because you make tiny changes. If you’re working with a system that anyone cares about, it’s also dangerous and stupid.

I’ve also worked with development organizations that take the opposite extreme. Even the most trivial server updates needed to be scheduled weeks in advance. In order to push the updated code, you had to notify everyone, take all servers down in the middle of the night, run through a long series of manual steps, and then do a lot of manual testing. When things in production aren’t quite how they are in the test environment, this is followed by a hasty rollback or panic-induced middle-of-the-night attempts at bug fixing.

Both of these extreme approaches are (maybe) appropriate in some environments. But neither are appropriate for a new web startup that’s trying to move quickly and still provide a reliable trustworthy experience to their customers.

At the previous company I worked for, we often talked about IMVU-Style Continuous Deployment as our ideal process, but it was always something “in the future”. We were hesitant (some of us more than others) to do automatic deployment without at least a little manual intervention. We always wanted to have more test automation, or a smoother deployment system, or whatever.

Since it seemed to be hard (for me anyway) to move to an existing development organization to a continuous deployment system, I started to wonder what would happen if you do it that way from day one? I got a chance to answer that question when I co-founded a startup last year. One of the very first things I did, before we had anyone using the site, was to create an solid automated test & deployment system that was as fast and easy as possible without being dangerous and stupid.

Here’s the basic workflow that happens in our office multiple times every day.

Step 0. We make changes on our local dev envirnments, with a bias toward making the smallest possible change that adds value. That could be a bug fix, correcting a typo, a stylistic tweak, a stubbed-out new feature, whatever. Once I’m confident in my local (manual and automated) testing that the change is good (not perfect, not feature-complete, but just better), I push that to my github repository.

From there, the continuous integration server pulls down the new code and does the following:

Step 1. Does the code still compile. If not, the build fails and everything stops.

Step 2. The build agent runs the unit tests (where “unit tests” are defined as tests that run with no external dependencies, these take just a few seconds). For anything that does require external (generally slow) dependencies (network API, databases, filesystem, whatever) we use test doubles (fakes, mocks, stubs, whatever).

This first feedback loop is about catching and preventing errors in core business logic and is generally measured in seconds, not minutes.

Step 3. The build agent runs a set of tests that rebuild the database from a reference schema and exercises all of the repository layer code.

Step 4. The build agent runs another set of tests that test our dependencies on external APIs (twitter, geolocation services, etc.)

These two sets of tests run in a few minutes, so the feedback loop isn’t quite as tight, but it’s still pretty darn fast. Basically, they make sure that the assumptions that we make with our test doubles in our unit tests aren’t totally wrong.

I’ve written about these sorts of automated test distinction a couple of years ago, in a post about the Automated Testing Food Pyramid.

Step 5. Provided that the entire gauntlet of tests has passed so far, the code gets automatically deployed to a staging server.

Step 6. There’s an additional set of tests that run against the staging web server. These tests can find configuration problems and code that just does the wrong thing in a web context. These tests are pretty shallow. They hit all of the user-facing pages/JSON endpoints and fail if anything is totally broken.

Step 7. The build artifacts are copied from TeamCity to a new folder on our productionvserver, and then the web server is reconfigured to serve from that folder instead of the folder it had been serving from.

At this point, we’ve verified that the core business (game, in this case) is OK, verified that the persistence stack works as expected, that our integration with external APIs works as expected, and that the code doesn’t completely break in a web context. We’ve done a zero-downtime deploy to the production web server.

That’s cool, but we’re not quite done yet. There’s two more steps.

Step 8. Run a set of tests against the production web site to make sure that all of the pages that worked a few moments ago still work.

Step 9.  Have external monitoring systems in place, so if your changes make things slow or unresponsive. You’ll know.  We use pingdom.

Yikes! There’s a bunch of distinct steps here, and it seems really complicated (because it is). But it’s all totally automated. All I need to do ?

git push origin master

Because there’s zero deployment effort on my part, I do this all the time.  I find it very energizing to know that I can just do stuff in minutes instead of hours or days or (heaven forbid) months.

If (when) something goes wrong, I’ll know immediately. If a bad bit of code manages to roll through the test gauntlet, I can roll back easily (just reconfiguring the web server to use the last known good set of code). I’ve only had to roll back a couple of times over the course of several months and 326 deployments.

Just like when the folks at IMVU wrote about this process, I’m sure that some people in the audience convinced that I’m a crazy person advocating a crazy way of working. Here are the objections I’ve heard before.

Yeah, but this doesn’t give your QA team any time to test the code before it goes out!
We’re a small startup. We don’t have a QA team. Problem solved.

Yeah, but isn’t that incredibly dangerous?
No. The safest change you can make to a stable production system is the smallest change possible. Also, we design the individual parts of the system to be as encapsulated as possible, so we don’t tend to have crazy side-effects that ripple through and create unintended bugs.

When we make a change or add a new feature, we can manually test the hell out of that one thing in isolation (before checking in) instead of feeling like we need to spend a lot of time and effort manually testing everything in order to ship anything.

Yeah, but what about schema changes?
For schema changes that are backwards compatible with the code that’s out there (e.g. new tables, whatever). We have a simple system that executes the appropriate DML on application startup.

For non-compatible schema changes and things like server migrations, we have to take down the site and do everything manually. Fortunately, we’ve only had to do that twice now.

Yeah, but you have to spend all of that time writing tests. What a waste!
The time we spend writing tests is like the time a surgeon spends washing their hands before they cut you open. It’s a proven way to prevent bugs that can kill you.

Also, we get that time back, and then some, by not having to spend nearly as much time with manual testing and manual deployments.

Yeah, but what about big new features you can’t implement in just one sitting?
Traditional software development models (both waterfall and agile methods like Scrum) are organized around the idea of “multiple features per release (or iteration)“. Continuous deployment is organized around the idea of “multiple releases (or iterations) per feature“. As a result, we end up pushing a lot of code for features that aren’t done yet. For the most part, these simply unavailable through the UI or only exposed to users who have particular half-built features associated with their accounts. I credit Flickr with this general approach.

Yeah, but that might work for a solo developer, but it can’t work for a team.
There are actually three developers on the team.

Yeah, but I’m sure this only works with very experienced developers
One of the guys on the team has only been programming for the last year or so and hasn’t ever worked on a web project before. Tight feedback loops help everyone.

Yeah, but what about code you want to share with other that you don’t want released?
We use github, so creating additional branches and sharing with them is trivial. We also have a dedicated “preview” branch that triggers a parallel test/deploy gauntlet that sends code to a staging server instead of the production servers.

Yeah, but this will never work at my organization because…
OK. That’s cool. Don’t try it if you feel that it won’t work for you. You’re probably right. You’re not going to hurt my feelings either way. I found something that’s working really well for me, and I want share my experience to show other people that it’s possible.

What this really means

Half of what makes this process work is that we’re honest with ourselves that we’re human and will make mistakes. If we have multiple tight feedback loops between when we’ve broken something and when we know we’ve broken it, it’s faster and easier and cheaper to fix those mistakes and prevent similar mistakes from happening again.

The other half is the idea that if you design, implement, test, and release exactly one thing at a time, you know with certainty which change introduced a problem instead of having to ask the question “which of the dozen or so changes that we rolled out this month/sprint/whatever are causing this problem”.

About the site

Victors United is an online turn-based strategic conquest game. You can play asynchronously or in real time. You can play against robots or humans. If you’re playing against humans, you can play against your friends or against strangers. Unlike some other popular web based social games that I don’t like to mention, this is a real competitive game where strategy and gameplay matter.

About the tech 

The tech here is kind of beside the point. This general approach would work just as well with different technology stacks.

The front end is HTML5 + JavaScript + jQuery. The backend is IIS/ASP.NET MVC2/SQL Server/Entity Framework 4. Our servers are hosted in the SoftLayer cloud. External monitoring is provided by pingdom.

The test gauntlet is a series of distinct nUnit assemblies, executed by TeamCity when we push new code to GitHub. There’s a single custom PowerShell script that pulls down the build artifacts and tells IIS to change what directory it serves code from.

Simple, yet polished

I have been thinking a lot about polish lately. How it’s often better to have a simple app that’s really polished than a more complex app that feels clunky.

My son is part of the 10% of the population that is left-handed. He’s also part of the 8% of male population that’s color blind. Imagine how he felt when he saw that the iPhone port of Peggle specifically supports color-blind lefties?

Oh no, not more of the same TDD discussion Tedium.

Every once in a while, otherwise reasonable people get together to argue about TDD with religious zeal. In the most recent flare-up, I’ve been disappointed that on all sides, as nobody is saying anything new.


At the risk of adding yet more noise, I did have a two nuanced thoughts that are at least new to me and I thought I would share them, along with a recent personal anecdote.  If this is obvious or old-hat to you, then I’m sorry.  If you think I’m  too stupid for words and that I’m drinking and/or selling snake-oil enriched kool-aid, I look forward to what will undoubtedly be informed and insightful feedback.

1. s/driven/aware/

The hardcore position of “never write a line of production code without a failing test for it” probably does more harm than good. Different kinds of code require varying degrees of effort (cost) to write and maintaintests for. Different kinds of code give varying degrees of benefit from test automation. Without always realizing it, developers make cost-benefit decisions all the time, and good development organizations empower their developers to act on those decisions.

That said, the cost-benefit decisions developers make must at least be informed decisions. A professional developer who hasn’t taken the time to learn how to use the appropriate test frameworks for their language/environment (jUnit, nUnit, whatever) is just plain negligent in 2009.  Test automation is just one tool in a competent developer’s toolbox, but a critical one.  I wouldn’t trust a carpenter who didn’t know what a hammer was, or a cardiologist who hadn’t bothered to learn about this newfangled angioplasty business.

Test-driven may not be appropriate for every context, but everyone needs to be at least test-aware.

2. s/first/concurrently/

Test-first is a really helpful approach, but it doesn’t work with the way everyone thinks, and mandating that everyone must always think in exactly the same way is the worst sort of micro-management.  The other extreme, writing test automation for a large system after it’s complete, is often prohibitively difficult and (frankly) boring as hell.

My advice is to always at least think about how you would write tests for your code before writing it. That will help keep you from painting yourself into untestable corners. Also, interlacing test writing immediately after you get a small subset of your system done is going to be much easier than testing the whole thing after the fact.  Personally, I move back and forth between writing the tests first and writing the code first. The key for me is that I’m working in short code-test-code-test cycles, using persistent (that is, I don’t throw it away when I’m done) test code as the primary mechanism for executing the code I’m writing as I’m writing it.  I don’t think of the process as being test-first, I think about testing concurrently with coding.

Recent Anecdote

Sure, anecdotes aren’t data, and they can’t prove anything, so take from it what you will

I just finished a pretty big refactoring project (that is a “pure” refactoring, the external interfaces and behavior of the existing stay the same but the underlying implementation was improved) of a system that had some decent test automation. Every time I got an edge case behavior wrong, introduced a side-effect, or removed a necessary side-effect (yuck), a test would go from green to red. This saved me at least a few days of development and testing time, and reduced the chances that I would release bugs to our QA guy (bad) or our production system (even worse).

It takes a good journalist to make software development interesting

Emily (who is best described as the heart of I Can Has Cheezburger) came into my office yesterday and looked around. “KING 5 news is going to be here, so we just want to make sure that there’s nothing offensive up anywhere”

There wasn’t. We used to have a copy of the Hot Chicks With Douchebags book as part of our display library, but that’s missing now. I was displaying my “Wrong-Face Panda” picture, but that’s meant to be disturbing, not offensive. Nonetheless, I tidied up the office a little bit and sat with better-than-normal posture as the news crew visited Ben in his little closet of an office, and then went around, poking their giant camera into different workspaces. They came to my office ,where Ben introduced us as the development team.

The news guy just shrugged and gave a sarcastic “Oh, software development, that’s really interesting” before walking away.

So I yelled back “Yeah, so is local news!”

That’s right, I actually came up with and executed a Winston Churchill-style zinger at the right time, not the day after.   I’m usually not so touchy, but that guy was just being a jerk. Think about it: would you come into some professional’s office and insult what they do?

The truth is, that the story of how we do software development is interesting. Some examples:

Our user activity is massive. We serve six million page views daily. We have a database of over four million funny pictures. A thousand new people register to participate in our community every day. We tally and act on hundreds of thousands of votes every day, in real time.

We’re a small team and we have to generalize and do more with less. We don’t have a dedicated test person, so we make our own robots to test our sites for us. We move quickly (turning around new ideas in days or weeks instead of months or years) yet we have really high stability with fully redundant systems that repair themselves if something goes wrong.  We deploy new code with zero downtime by pulling a server out of service,  upgrading it, and putting it back into service after we’ve tested it.

All of our office infrastructure is virtual. There are no desktop phones or LAN servers. We use Internet-based tools like Skype,  Tokbox, Google Docs, and ReviewBoard to collaborate. Some key members don’t even work from this office, yet they are just as productive as someone who works right here. Our office is essentially paperless, the only time I’ve ever used an office printer was for personal use (sorry).

We have created a public API which opens up our systems to any developer who wants to contribute or use our content in their programs. You can take pictures on your iPhone, drop text on them, and send them directly to us using a program that some guy made for free just because he wanted to.  We’re plugged in to the emergent web ecosystem; we integrate with WordPress and Twitter and YouTube and Digg and Facebook. We’re working on all sorts of new stuff that will be really cool.

We’re living and working in the bright and shiny future of tomorrow, as a profitable Web 2.0 company.   The truth is, I don’t really care if some old-media guy and his ever-shrinking audience doesn’t get it.

Script Frenzy 2009 – Writing a Screenplay in 30 days. Here I go.

When I was about to start my first attempt at National Novel Writing Month, a friend of mine said “Martin, you’ll have no trouble with this, you have a skill for telling things as they are

“Thanks, but I’m writing fiction”

“Oh.Never mind, then.”

In the same spirit (and organized by the same lunatics) as National Novel Writing Month (every November) is ScriptFrenzy (every April). I participated in ScriptFrenzy in its premiere year and managed to finish a flawed but readable script for a feature film about an insecure superhero investigating a crime involving his former partner who was framed for taking performance enhancing drugs.

This year’s script is for a two-hour pilot for a television drama. It’s set a few years after a mysterious natural disaster which has destroyed every large city on Earth. My characters are (so far) a former Ju-Jitsu instructor turned fisherman turned militia leader, an agrarian bible scholar turned underground spy, a cokehead airline pilot with political ambitions, a fugitive former CIA agent taking refuge with old mafia connections, a shameless disaster profiteer, a teenage girl trying to break away from the UFO cult her family is in, a HAM radio geek turned talk radio superstar, and a cute young journalist who rides a Vespa (her character needs some more depth, obviously).

I’m working under this basic formula, but it’s changing from moment to moment:

(Left Behind – Kirk Cameron/evangelical message) + (Battlestar Galactica – Cylons/Space Travel) + (The Sopranos – pop psychology)  + ( World War Z – Zombies ) + (X Files – creepy sideshow episodes/aliens)

The best thing about writing a TV pilot instead of a feature film is that you don’t have any pressure to wrap things up. I’m going to just open up a whole bunch of messy loose ends and leave them there with an outlandish cliffhanger ending. It seems to work for J.J. Abrams.

After the first two days, I’m off to an OK start. Last night I literally fell asleep at the keyboard and typed an entire sentence with my eyes closed. Upon further inspection, I had to throw it out as it had no vowels in it. Tonight was better and I managed to get up to 8 pages (target is 100 pages in 30 days, so I’m a page or so ahead of schedule).

A big part of making a writing project like this succeed is the visible public commitment to meeting the deadline. This is the same reason that many teams get benefit from doing daily stand-up meetings, is that coders can stay focused more easily when they commit to action in front of their peers. By telling everyone that I’m doing this, it’s a lot harder to just give up silently and go back to watching Hulu or playing iPhone games.

Wish me luck.

One of the Coolest Things I’ve seen in a while.

Construx to Offer Free Training to Laid-Off Software Developers

This is a total win-win.

Laid off people get some training to keep themselves sharp when they’re not working, and a recent line item to put on their resume.

Construx gets some additional brand awareness/mind share/word of mouth (just think of all of those resumes going out to their target market). They also get the advantage of filling up their classes at a hard time to do so. Trainings like theirs (I’ve been to many) work better with a critical mass of participants.

Here’s hoping other companies will do creative things like this.