Posts Tagged ‘Continuous Integration’

How Mature Is Your Continuous Integration?

November 9, 2011 8 comments

As I’m sure I’ve ranted about mentioned in the past, Continuous Integration is far more than just a collection of tools and scripts. It’s “a practice”, a way of doing something, and it has to be part of our working culture to be truly effective.

I’ve seen instances of CI implemented which are truly magnificent, using great tools, great architecture, very smart scripts and a good process, but I’ve also seen this system fail. Unfortunatley, it’s all too easy to have your wonderful system, and then have it ignored unless there is the right level of buy-in from the people who this system is meant to cater for, nameley development, QA and Management.

The way I currently see it, is that there are a number of levels of CI maturity. I’ll just call these levels “Level 1″, “Level 2″ and so on, rather than “Highly Immature”, “Stroppy Teenager” etc:

Level 1

No CI tools to speak of, no CI process. I’ve been there. Builds take about a day to get working. It’s a nightmare. I still shiver just thinking about it.

Level 2

We’ve got some CI tools like cruise control, repeatable builds, but no CI process. We’ve basically got a front-end to a system of chaos. Most of the builds are broken, but you now have a nice way of visualising that, and nobody cares. It’s Level 1 with a pretty wrapper on it.

Level 3

We’ve got a system, but not the right tools. We’ve got a policy of running our tests locally before checking-in, and some poor soul somewhere is left with the task of making the “official” builds for passing to QA. These builds will usually fail and everyone will have to chip in to help sort out the mess until a build can be made. We desperately need a computer to do this build lark for us!

Level 4

We’ve got some rudimentary tools, like Cruise Control or Jenkins, but we’re not using them to their full capacity, but we’ve got a build monkey! The build monkey does his or her best to make sure that people are aware that they’ve broken the build. The build monkey sets up the CI system and makes changes whenever necessary. The build monkey is the first to look into every build failure. The build monkey goes on holiday and the whole place grinds to a halt.

Level 5

We’ve got the tools, we’ve got the process, but nobody’s listening to us!!! All the tools are in place, we’ve got a suitable CI system and maybe we’re even trying to do continuous delivery. The build system is virtualised and we have a release engineering team (the collective noun for a group of build monkeys is a “release engineering”). The only trouble is, the unit test coverage is apalling and people don’t fix their broken builds, despite the fact that we’ve got a nice shiny wiki page saying we should aim to have 95% unit test coverage and broken builds should be fixed within 3o mins.

Level 6

We’ve got the tools, the processes and we’ve got management buy-in! This is looking good, we now have a lovely system, which our team of build engineers looks after, and we have a semi-compliant dev team who get told off if they don’t play ball! We’re all heading in roughly the right direction

Level 7

We’ve got the tools, the process and the right culture! Everyone has buy-in to the build system. Developers and build enginners alike can be trusted to edit build files and even the CI configuration because we all clearly understand what we’re trying to achieve. Best practices are being observed and so our build engineering team don’t need to spend all day chasing people or working on trivial tasks. Our time can be better invested and productivity increased.


Ultimately we’re all responsible for looking after the CI system – it’s for our own benefit afterall. As a developer I want to make sure I have some fast and reliable feedback on the quality of my code changes. If I see my build has failed, I would actually want to find out why, rather than ignore it. As a build engineer I want our CI system to be providing useful feedback to our developers, and useful information to management – if it isn’t, or if this “useful” information isn’t being acted upon, then it’s not really useful at all, and my job is less fulfilling! All of this means that we all have some responsibility to occasionally look under the hood and see what’s going on, and try to figure out why the system is telling me that something isn’t working quite right.

The hardest part to get right, particularly in distributed teams or in companies over a certain size, is the culture. You have to have a team of build engineers and developers who all understand the big picture. Developers need to understand that they are instrumental in making the system work – their input is vital, and they have to understand clearly what benefits they will personally get from this system, otherwise they’ll ignore it. Build engineers in turn need to understand that the more you are able to devolve the ownership of the system, the better it can work, and the more buy-in you will get in return. The build system needs guardians, but it doesn’t need treating like a holy relic.

Coping With Big C.I.

October 20, 2011 5 comments

Last night I went along to another C.I. meetup to listen to Tom Duckering, a consultant devops at Thoughtworks, deliver a talk about managing a scaled-up build/release/CI system. In his talk, Tom discussed Continuous Delivery, common mistakes, best practices, monkeys, Jamie Oliver and McDonald’s.

Big CI and Build Monkeys

buildmonkeyFirst of all, Tom started out by defining what he meant by “Big CI”.

Big CI means large-scale build and Continuous Integration systems. We’re talking about maybe 100+ bits of software being built, and doing C.I. properly. In Big CI there’s usually a dedicated build team, which in itself raises a few issues which are covered a bit later. The general formula for getting to Big CI, as far as build engineers (henceforth termed “build monkeys”) are concerned goes as follows:

build monkey + projects = build monkeys

build monkeys + projects + projects = build monkey society

build monkey society + projects = über build monkey

über build monkey + build monkey society + projects = BIG CI


What are the Issues with Big CI?

Big CI isn’t without its problems, and Tom presented a number of Anti-Patterns which he has witnessed in practice. I’ve listed most of them and added my own thoughts where necessary:

Anti-Pattern: Slavish Standardisation

As build monkeys we all strive for a decent degree of standardisation – it makes our working lives so much easier! The fewer systems, technologies and languages we have to support the easier, it’s like macro configuration management in a way – the less variation the better. However, Tom highlighted that mass standardisation is the work of the devil, and by the devil of course, I mean McDonald’s.

McDonald’s vs Jamie Oliver 

ronnysmug git

Jamie Oliver might me a smug mockney git who loves the sound of his own voice BUT he does know how to make tasty food, apparently (I don’t know, he’s never cooked for me before). McDonald’s make incredibly tasty food if you’re a teenager or unemployed, but beyond that, they’re pretty lame. However, they do have consistency on their side. Go into a McDonald’s in London and have a cheeseburger – it’s likeley to taste exactly the same as a cheeseburger from a McDonald’s in Moscow (i.e. bland and rubbery, and nothing like in the pictures either). This is thanks to mass standardisation.

Jamie Oliver, or so Tom Duckering says (I’m staying well out of this) is less consistent. His meals may be of a higher standard, but they’re likely to be slightly different each time. Let’s just say that Jamie Oliver’s dishes are more “unique”.

Anyway, back to the Continuous Integration stuff! In Big CI, you can be tempted by mass standardisation, but all you’ll achieve is mediocrity. With less flexibility you’re preventing project teams from achieving their potential, by stifling their creativity and individuality. So, as Tom says, when we look at our C.I. system we have to ask ourselves “Are we making burgers?”

Are we making burgers?

- T. Duckering, 2011

Anti-Pattern: The Team Who Knew Too Much

There is a phenomenon in the natural world known as “Build Monkey Affinity”, in which build engineers tend to congregate and work together, rather than integrate with the rest of society. Fascinating stuff. The trouble is, this usually leads the build monkeys to assume all the responsibilities of the CI system, because their lack of integration with the rest of the known world makes them isolated, cold and bitter (Ok, I’m going overboard here). Anyway, the point is this, if the build team don’t work with the project team, and every build task has to go through the build team, there will be a disconnect, possibly bottlenecks and a general lack of agility. Responsibility for build related activities should be devolved to the project teams as much as possible, so that bottlenecks and disconnects don’t arise. It also stops all the build knowledge from staying in one place.

Anti-Pattern: Big Ball of CI Mud

This is where you have a load of complexity in your build system, loads of obscure build scripts, multitudes of properties files, and all sorts of nonsense, all just to get a build working. It tends to happen when you over engineer your build solution because you’re compensating for a project that’s not in a fit state. I’ve worked in places where there are projects that have no regard for configuration management, project structures in source control that don’t match what they need to look like to do a build, and projects where the team have no idea what the deployed artifact should look like – so they just check all their individual work into source control and leave it for the build system to sort the whole mess out. Obviously, in these situations, you’re going to end up with some sort of crazy Heath Robinson build system which is bordering on artificial intelligence in its complexity. This is a big ball of CI mud.

Heath Robinson Build System

Heath Robinson Build System a.k.a. "a mess"

Anti-Pattern: “They” Broke MY Build…

This is a situation that often arises when you have upstream and downstream dependencies. Let’s say your build depends on library X. Someone in another team makes a change to library X and now your build fails. This seriously blows. It happens most often when you are forced to accept the latest changes from an upstream build. This is called a “push” method. An alternative is to use the “pull” method, which is where you choose whether or not you want to accept a new release from an upstream build – i.e. you can choose to stick with the existing version that you know works with your project.

The truth is, neither system is perfect, but what would be nice is if the build system had the flexibility to be either push or pull.

The Solutions!

Fear not, for Tom has come up with some thoroughly decent solutions to some of these anti-patterns!

Project Teams Should Own Their Builds

Don’t have a separated build team – devolve the build responsibilities to the project team, share the knowledge and share the problems! Basically just buy into the whole agile idea of getting the expertise within the project team.

Project teams should involve the infrastructure team as early as possible in the project, and again, infrastructure responsibilities should be devolved to the project team as much as possible.

Have CI Experts

Have a small number of CI experts, then use them wisely! Have a program of pairing or secondment. Pair the experts with the developers, or have a rotational system of secondment where a developer or two are seconded into the build team for a couple of months. Meanwhile, the CI experts should be encouraged to go out and get a thoroughly rounded idea of current CI practices by getting involved in the wider CI community and attending meetups… like this one!

Personal Best Metrics

The trouble with targets, metrics and goals is that they can create an environment where it’s hard to take risks, for fear of missing your target. And without risks there’s less reward. Innovations come from taking the odd risk and not being afraid to try something different.

It’s also almost impossible to come up with “proper” metrics for CI. There are no standard rules, builds can’t all be under 10 minutes, projects are simply too diverse and different. So if you need to have metrics and targets, make them pertinent, or personal for each project.

Treat Your Build Environments Like They Are Production

Don’t hand crank your build environments. Sorry, I should have started with “You wouldn’t hand crank your production environments would you??” but of course, I know the answer to that isn’t always “no”. But let’s just take it as read that if you have a large production estate, to do anything other than automate the provision of new infrastructure would be very bad indeed. Tom suggests using the likes of Puppet and Chef, and here at Caplin we’re using VMWare which works pretty well for us. The point is, extend this same degree of infrastructure automation to your build and CI environments as well, make it easy to create new CI servers. And automate the configuration management while you’re at it!

Provide a Toolbox, Not a Rigid Framework

Flexibility is the name of the game here. The project teams have far more flexibility if you, as a build team, are able to offer a selection of technologies, processes and tricks, to help them create their own build system, rather than force a rigid framework on them which may not be ideal for each project. Wouldn’t it be nice, from a build team perspective, if you could allow the project teams to pick and choose whichever build language they wanted, without worrying that it’ll cause a nightmare for you? It would be great if you could support builds written in Maven, Ant, Gradle and MSBuild without any problems. This is where a toolkit comes in. If you can provide a certain level of flexibility and make your system build-language agnostic, and devolve the ownership of the scripts to the project team, then things will get done much quicker.

Consumer-Driven Contracts

It would be nice if we could somehow give upstream builds a “contract”, like a test API layer or something. Something that they must conform to, or make sure they don’t break, before they expose their build to your project. This is a sort of push/pull compromise.

And that pretty much covers it for the content of Tom’s talk. It was really well delivered, with good audience participation and the content was thought-provoking. I may have paraphrased him on the whole Jamie Oliver thing, but never mind that.

It was really interesting to hear someone so experienced in build management actually promote flexibility rather than standardisation. It’s been my experience that until recently the general mantra has been “standardise and conform!”. But the truth is that standardisation can very easily lead to inflexibility, and the cost is that projects take longer to get out of the door because we spend so much time compromising and conforming to a rigid process or framework.

Chatting to Christian Blunden a couple of months back about developer anarchy was about the first time I really thought that such a high degree of flexibility could actually be a good thing. It’s really not easy to get to a place where you can support such flexibility, it requires a LOT of collaboration with the rest of the dev team, and I really believe that secondment and pairing is a great way to achieve that. Fortunately, that’s something we do quite well at Caplin, which is pretty lucky because we’re up to 6 build languages and 4 different C.I. systems already!

8 Principles of Continuous Delivery

August 4, 2011 10 comments

continuous deliveryDave Farley co-authored “Continuous Delivery”, an excellent book in the Martin Fowler signature series, which goes into great detail about the evolution of Continuous Integration, and how to achieve continuous delivery (or continuous deployment) using “build pipelines”.

I went along to hear Dave Farley give a talk on Continuous Delivery and how they’re doing it where he works, at LMAX. It was a really great session and he managed to cover, in quite a short session, a great deal of content from in the book. I’ve put together a highlight of what he covered in the talk, mixed with my own take on things

Here’s what I learned…

Continuous delivery is basically the logical extension of Continuous Integration  – it’s a more holistic solution than C.I. though, as it encapsulates a lot more than just the development of software.

For instance, continuous delivery focuses a lot more on requirements than C.I. ever did, and involves a great deal more people on the delivery chain than traditional C.I. as well. It also has a greater customer focus than C.I.

Now, here’s something I didn’t know about continuous delivery…

There are 12 principles behind the agile manifesto. the first of which is:

Our highest priority is to satisfy the customer through early and continuous delivery of valuable software

Well who’d have thought it? Continuous delivery was mentioned waaaaay back in the days of the agile manifesto, some 2500 years BC* and yet for most of us it seems like a pretty new idea.

Continuous delivery is based on the use of smart automation. This is all about creating a repeatable and reliable process for delivering software. You have to automate pretty much everything in order to be able to achieve continuous delivery. manual steps will get in the way or become a bottleneck. This goes for everything from requirements authoring to deploying to production.

The focus is on the finished article – again, this is described as being:

Working software in the hands of the user

software in the hands of the user

software in the hands of the user

Because the focus is on the software in the hands of the user, there’s less tendency from a developers perspective, to simply chuck software over the wall to the QA team, and similarly to the Netops/production team.

Continuous delivery is all about getting that product out there, and getting the feedback from the users. This might mean delivering “unfinished” demo software during your development iterations, and getting your users to give valuable early feedback, or it might mean deploying experimental software to a website cluster and tracking how successful this new site is as compared to the existing system. Either way, it’s all about feedback loops. Essentially you want to have as rapid a feedback loop with your users as possible.

Feedback loops are familiar to everyone who has worked on a Continuous Integration system. In C.I. feedback loops are generally about getting test feedback (unit test, acceptance test, performance test etc) as quickly as possible – “Fail Fast” – as you’ve probably heard.

Continuous Delivery, as described, takes this idea to it’s logical conclusion, and gets the users involved in the feedback loop. This is a good example of how Continuous Delivery is more holistic than its C.I. predecessor. In Continuous Delivery, the feedback loop provides feedback not only on the quality of your code, but on the quality of your requirements, and the quality of your processes for delivering software.

8 Principles of Continuous Delivery

  1. The process for releasing/deploying software MUST be repeatable and reliable. This leads onto the 2nd principle…
  2. Automate everything! A manual deployment can never be described as repeatable and reliable (not if I’m doing it anyway!). You have to invest seriously in automating all the tasks you do repeatedly, and this tends to lead to reliability.
  3. If somethings difficult or painful, do it more often. On the surface this sounds silly, but basically what this means is that doing something painful, more often, will lead you to improve it, probably automate it, and this will eventually make it painless and easy. Take for example doing a deployment of a database schema. If this is tricky, you tend to not do it very often, you put it off, maybe you’ll do 1 a month. Really what you should do is improve the process of doing the schema deployments, get good at it, and do it more often, like 1 a day if needed. If you’re doing something every day, you’re going to be a lot better at it than if you only do it once a month.
  4. Keep everything in source control – this sounds like a bit of a weird one in this day and age, I mean seriously, who doesn’t keep everything in source control? Apparently quite a few people. Who knew?
  5. Done means “released”. This implies ownership of a project right up until it’s in the hands of the user, and working properly. There’s none of this “I’ve checked in my code so it’s done as far as I’m concerned”. I have been fortunate enough to work with some software teams who eagerly made sure their code changes were working right up to the point when their changes were in production, and then monitored the live system to make sure their changes were successful. On the other hand I’ve worked with teams who though their responsibility ended when they checked their code in to the VCS.
  6. Build quality in! Take the time to invest in your quality metrics. A project with good, targeted quality metrics (we could be talking about unit test coverage, code styling, rules violations, complexity measurements – or preferably, all of the above) will invariably be better than one without, and easier to maintain in the long run.
  7. Everybody has responsibility for the release process. A program running on a developers laptop isn’t going to make any money for the company. Similarly, a project with no plan for deployment will never get released, and again make no money. Companies make money by getting their products released to customers, therefore, this process should be in the interest of everybody. Developers should develop projects with a mind for how to deploy them. Project managers should plan projects with attention to deployment. Testers should test for deployment defects with as much care and attention as they do for code defects (and this should be automated and built into the deployment task itself).
  8. Improve continuously. Don’t sit back and wait for your system to become out of date or impossible to maintain. Continuous improvement means your system will always be evolving and therefore easier to change when needs be.

To go with these principles there are also:

4 Practices of Continuous Delivery

  1. Build binaries only once. You’d be staggered by the number of times I’ve seen people recompile code between one environment and the next. Binaries should be compiled once and once only. The binary should then be stored someplace which is accessible only to your deployment mechanism, and your deployment mechanism should deploy this same binary to each successive environment…
  2. Use precisely the same mechanism to deploy to every environment. It sounds obvious, but I’ve genuinely seen cases where deployments to QA were automated, only for the production deployments to be manual. I’ve also seen cases where deployments to QA and production were both automated, but in 2 entirely different languages. This is obviously the work of mad people.
  3. Smoke test your deployment. Don’t leave it to chance that your deployment was a roaring success, write a smoke test and include that in the deployment process. I also like to include a simple diagnostics test, all it does it check that everything is where it’s meant to be – it compares a file list of what you expect to see in your deployment against what actually ends up on the server. I call it a diagnostics test because it’s a good first port of call when there’s a problem.
  4. If anything fails, stop the line! Throw it away and start the process again, don’t patch, don’t hack. If a problem arises, no matter where, discard the deployment (i.e. rollback), fix the issue properly, check it in to source control and repeat the deployment process. A lot of people comment that this is impossible, especially if you’ve got a tiny outage window to deploy things to your live system, or if you do your production changes are done in the middle of the night while nobody else is around to fix the issue properly. I would say that these arguments rather miss the point. Firstly, if you have only a tiny outage window, hacking your live system should be the last thing you want to do, because this will invalidate all your other environments unless you similarly hack all of them as well. Secondly, the next time you do a deployment, you may reintroduce the original issue. Thirdly, if you’re doing your deployments in the middle of the night with nobody around to fix issues, then you’re not paying enough attention to the 7th principle of Continuous Delivery – Everybody has responsibility for the release process. Unless you can’t avoid it, I wouldn’t recommend doing releases when there’s the least amount of support available, it simply goes against common sense.

* Approximate date.

Continuous Delivery in Practice

A couple of months ago I was fortunate enough to be invited to the Thoughtworks live 2011 event in London. The main topics of this event were agile (as you’d expect from Thoughtworks) and Continuous Delivery. The event was run over 2 days, the first day included talks from Jez Humble and Martin Fowler, as well as a number of other speakers (Dave West did a session on agile vs the rest, Beyond BudgetingBjarte Bogsnes presented a very interesting session called “Beyond Budgeting”, and Scott Durchslag was guest speaking about how agile has worked at Expedia, and his interest in Continuous Delivery). My colleague Steve Morgan was also in attendance on the first day and has produced this excellent post on the contents of day 1. I won’t say much more about the first day because Steve’s post covers it better than I ever could (he cheated by taking notes/paying attention). However, I will just add that it was great to see so many people who genuinely seemed passionate about the evolution of agile, and the coffee breaks were a great opportunity to pick the brains of Messrs Fowler and Humble. I particularly enjoyed the “Beyond Budgeting” talk from Bjarte, and am happy to say he’s written a book about it, which you can buy on the internets!

The only other thing I would say about day 1 was that there was a reasonably good choice of biscuits. Biscuit variety is important and mustn’t be underestimated.

Day 2

Day 2 was somewhat more hands on than the first day, and also more tools-oriented. It started off with another session from Jez Humble and Martin Fowler, where they discussed continuous delivery, covering some of the contents of Jez’s book, and also going into detail about branching (feature branching vs Continuous Integration).Continuous delivery book The sessions then moved on to cover some of the products being produced at Thoughtworks Studios. There were talks from Andy Kemp and Suzie Prince about their products Mingle and Twist. Mingle is marketed as an agile project management tool. I’ve not used it myself but it seems to be based around shared workspaces and good requirements tracking. As you’d expect, it seems to integrate well with the other Thoughtworks products, which is probably one of its main advantages. Twist is a functional testing platform, which is very agile-centric in that it allows you to run requirements specs as tests in the “As a user, I want to…” style. Again it’s the integration with the other tools and products that made it look good to me. I’ve used a lot of agile tools recently, which all seem to be great on their own, but putting them all together so that I can track a requirement through to a test and a change through to a build can be a lot of hard work. The final product that they presented was Go, which is their Continuous Integration system, and they even showed us how they used Go to deliver builds of Mingle, Twist and even Go itself (talk about eating your own dogfood).

The centrepiece of day 2 though was of course my very own talk on how we at Caplin Systems are using Go in our Continuous Delivery system :-) I was invited to present a session on how Go is helping us achieve our Continuous Integration goals, and how we are using it to implement our own brand of Continuous Delivery. I’ve embedded my presentation above – sorry it’s not a video. I won’t go into too much detail (I’ll save you the lecture), but basically we’re using build pipelines along with a high degree of automated tests to deliver builds which are suitable for deployment. The other feature I have to mention is how Go manages multiple agents. We have about 60 active agents which Go manages. A build can be farmed out to any of these 60 agents, and if a particular resource is needed (let’s say I need to run a test on a particular OS, like Centos) then Go can be configured to send the builds to the right agents. Particular builds can be configured to be excluded from certain agents, meaning the system is highly configurable.

In the afternoon we had an open-space session, during which I spent most of my time with a group discussing database deployments and how to bring db changes under Continuous Integration. It seems there are still a lot of people around who feel that this aspect is largely overlooked with respect to Continuous Integration, and this was reflected in the way people were talking about using manual db compare tools as a way of deploying db changes to production. My own feelings on this are that database changes should be treated more like code changes, with each change scripted and deployed as a code change would be. There needn’t be destructive changes, and a good set of test data should help catch the issues that are often only found in production.

Greasemonkey script for CI system

Here in Caplin Towers (it’s not really called that) we’ve got a couple of projectors displaying the Continuous Integration builds up on the walls. It’s pretty useful until you get to the point where you’ve got more projects than space on the wall. We got to that point a while ago, and have had to resort to only displaying the “most important” builds on the wall. Clearly this is not very cool, because all the builds are important.

Sorry, there's no room here!

Sorry, there's no room here!

I decided to write a script which would scroll through all of the build groups and display this on the wall. I worked out that it would take about a minute to scroll through the whole lot, with a 4 second pause on each build group. My first thought was to use Watir (a ruby based browser scripting tool), and this would have probably worked fine on a Jenkins, Bamboo or CruiseControl system, but not for Go (I needed my solution to work for Go as many of our builds are in this system at present). You see, Go displays build groups by use of “views” (like Jenkins does). Unfortunately in Go there isn’t a different url for each view, meaning I can’t just write a simple ruby script that loads up a different page for each build group. I guess it must be handled by javascript.

So, I decided to try selenium. In theory this should have worked fine, and indeed it would have if I could be bothered to spend a bit more time on it. My plan was to record a journey which loaded up each view, one after another, and then play back this journey using selenium RC so that I could put it into a scheduled cron job and have it run over and over again. Like I said, in theory it works fine, but in practice it wasn’t such a great idea afterall. Firstly, there’s always that delay as selenium initializes and loads the browser, then there’s the presence of the selenium window, and then there’s the problem of having to update the script every time a new build group is added. I know most of these issues can be overcome fairly easy, especially if you’re selenium savvy or if you have a java framework for laoding and running selenium tests in place. I was just about to go down the route of writing my journey in java (mainly so that I can manipulate the window sizes more easily), when my colleague Edmund Dipple, said “I saw you struggling, so I’ve knocked this up” and showed me a greasemonkey script which does exactly what I was looking for. :-)

Basically the script runs through each pipeline group, one after the other, and pauses for 5 seconds on each one before moving on. Perfect. He used the chrome developer tools (or you could use Firebug on Firefox) to find out the name of the pipeline group container (which turned out to be “pipeline_groups_container”) and then iterate through each of the child elements (the child elements represent each pipeline group). The full script is here:

var timeout = 5000;

var counter = 0;
var groups = document.getElementById(“pipeline_groups_container”).children;
var groupsLength = groups.length;

function scroll()

groups[i].style.display = “none”;
groups[counter].style.display = “block”;


if(counter == groupsLength)
counter = 0;




And now we see each build group on screen, one at a time:

This is one pipeline group....

...and this is another

What is in a name? Usually a version number, actually.

July 7, 2011 15 comments

Another fascinating topic for you – build versioning! Ok, fun it might not be, but it is important and mostly unavoidable. In an earlier blog I outlined a build versioning strategy I was proposing to use with our Java builds. Since then, the requirements have changed, as they tend to, and so I’ve had to change the versioning convention.

Essentially, what I’m after is a way of using artifact version numbers to tell me some useful at-a-glance information about the artifact I have created. Also, customers want the version number to meet their expectations – that is, when they get a new build, they want to see an easily identifiable difference in the version number between the new build and their old one. What they don’t want is a long complicated list of numbers which are hard to distinguish. For instance, it’s much easy to identify which of the following 2 versions is the latest:

  • 5.0.1
  • 5.0.4

but it’s not so easy to work out which of these is the latest:


As we’re practicing continuous delivery, any given check-in can feasibly produce a release build. So, I would like some way of identifying exactly which check in produced my builds, or at least have a way of working out which bits of source code went into my released package. There are a couple of ways we can do this:

Tag the source code – We could make the builds tag the source code in our SCM system (Perforce) with every build. This is relatively easy to do using Ant and Maven. With Ant there are numerous different ways of doing it depending on your SCM system, for instance, with subversion you need to use the SvnAnt tasks from subclipse ( and basically perform a copy of your source url:

 <copy srcUrl=”${src.url}” destUrl=”${dest.url}” message=”${version.num}”/>

(this is because tags in svn are just cheap copies with a label).

With Maven you just need to use the release plugin – this automatically handles tagging for you.

Tagging the source code is great – it keeps the version numbers as simple as I’d like, and it’s nicely traceable. However, it’s time consuming, and can result in a lot of tags.  The other problem is, I can’t tell which check-in caused the build just by looking at the version number of an artifact.

Use the commit number in the build version - We use a build version of Major.Release.Patch-Build in our artifacts. The build number used to be an auto-incrementing number – this worked fine but it didn’t give us a link back to which commit had caused the build to be made. So, I decided to use the perforce changelist id (i.e. the commit version) as the build number in the version, so that builds would end up looking something like this: 1.0.0-11531.

The problem here is that the version number is not customer friendly – so I remove the build number as a final step, before the builds get released to customers. To track what version the customers have got, I still keep a record of the full build number (including the commit number) in the release notes, and I could also easily inject it into an assembly info or properties/config file if I so wished, so that customers could very easily read out the full version number just by looking in a menu somewhere.

There were several obstacles I had to overcome to get this working. The first obstacle, and really this was the one that stopped me from tagging the source code, was that the maven release plugin is abysmal when it comes to continuous delivery. I needed to use the release plugin to tag the source code, but one of the other things that the maven release plugin does is to remove the word SNAPSHOT, increment the version number, and check the pom back into source control. This would cause another build to trigger in the CI system, which in turn would increment the build number etc and cause another build to trigger – so on and so on. Basically it would create a continually building project.

So I have decided not to use the maven release plugin at all – it doesn’t seem to fit in with Continuous Delivery. In order to create potential release candidates with every successful build, I’ve removed the word SNAPSHOT from all the poms, so we aren’t making any snapshot builds anymore either (except when you build locally – more on that later). The version in the poms now takes the P4 commit number, which is injected via the Continuous Integration system, which in my case is Go. Jenkins also supports this, using the subversion plugin (if you use subversion), which sets an environment variable with the svn revision number (more details here). The Jenkins Perforce plugin does the same thing, setting the P4_CHANGELIST environment variable – so it can easily be consumed (more details here).

Go takes the P4 changelist number and puts it in an environment variable called “GO_PIPELINE_LABEL”. I read this variable in, and assign it to a property called p4.revision. I do this in the command that kicks off the build, so that it overwrites a default value which I can keep in my pom – this is useful because it means my colleagues and I don’t have to make any changes to the pom if we want to run a build locally (bear in mind if we run it locally this environment variable won’t exist on our PCs, so the build would otherwise fail). Here’s a basic run down of a sample pom, with more details to follow:


<description>Description about this application</description>







The value for p4.revision is “SNAP” by default, meaning that if I make a local build, I’ll get an artifact with the version 5.0.2-SNAP. I know that these builds should never be promoted to production or handed to customers because the word SNAP gives it away.  However, when a build is created by the CI system, the following command is passed:

clean deploy sonar:sonar -Dp4.revision=${env.GO_PIPELINE_LABEL}

This overwrites the value for p4.revision, passing in the Perforce commit number, and the build will create something like 5.0.2-1234 (where 1234 is my imaginary p4 commit number).

I’ve added a property called main.version, which is the same as the full version but without the build number. I’ve done this so that I can package up my customer builds (ina  zip) and label them with the version 5.0.2. After all, customers don’t care about the build number.

An important policy to follow is once a build is released to a customer, one of the other version numbers MUST be increased, meaning all further builds will be at least 5.0.3. The decision of which version number to increase depends on various business factors – I like to increase the 3rd number if I’m releasing a patch to a previously released build. If I’m releasing new functionality I increase the second number. The first number gets increased for major releases. The whole issue of version numbers becomes a lot less complicated if you’re in the business of releasing software to web servers and you don’t actually have to hand software over to customers. In this instance, I just keep the full version number with the build number at the end, as it’s usually someone like me who has to look after the production system anyway!

The Boy Who Cried Wolf – Why Broken Builds Must Not Be Ignored!

June 22, 2011 4 comments

We’ve all heard the fable of the boy who cried wolf, an old tale written by a Greek slave who lived a long time ago and liked telling stories. I must stress thought that this was just a story, but like many good stories (Star Wars, Gremlins 2) it’s based on true events. It’s a little known fact (which I have just made up) that the story of the Boy Who Cried Wolf is actually based on an ancient Continuous Integration system (possibly belonging to Spartatech inc, a leading software development company of from around 600BCE).

The are only very sketchy records of what actually happened during this historical event, but here’s what we know for sure*:

  • The Continuous Integration system compiled code and ran unit tests.
  • The unit tests were followed by acceptance tests, which in turn were followed by integration tests.
  • The integration tests were followed by cross-platform tests.

One day, the C.I. system alerted the developers, and anyone else who would listen, that one of the builds was failing!



All the workers gathered around the C.I. system to take a look at the error, only to discover that in actual fact, the problem was that the machine on which the tests were running had restarted, thanks to a windows update! The developers went back to work and thought no more of it.

The very next day, the C.I. system went ballistic again, alerting the developers of yet another failure. Once again the team took notice and looked into the error. This time they discovered that the test machine was running slowly and their unit test had timed out. They restarted the machine and it all passed.

By the following week, the C.I. system had alerted the team to 5 other “failed” builds, which were simply a result of the test servers behaving oddly, and no change to the code was required at all. By the end of that week the dev team had stopped paying attention to these alerts, because they all had proper jobs to do, and a lot of work to get through by the end of the sprint (they were agile, even back then – so if you still work according to “Waterfall” THAT’S how far behind the times you are).

Then, one day, a developer checked in a piece of code which failed a unit test. The C.I. system rightly alerted the development team again, but this time nobody came running, in fact, nobody paid the blindest bit of notice. They were all so used to ignoring the C.I. system that when a real problem finally arose, it wasn’t picked up by anyone. Anyway, cutting an already long story a bit shorter, the bug was a biggie, and the next release of their software was so poor that Spartatech inc, the biggest employer in Sparta, went out of business making everyone redundant. This is what basically led to the collapse of Sparta, not sure if you knew that. And here concludes your exceedingly dodgy history lesson.

Back to the present-time: We all know that false-negatives are the enemy of a good Continuous Integration system, they lead us down a path from which it’s increasingly hard to recover. The problem is that it’s just so easy to get into that situation.  Thankfully, there are a few “Continuous Integration best practices” which we can follow, which can help us keep our system in good nick:

  • Make sure the servers on which you run your builds are cleaned regularly, preferably before every build. I would suggest a clean image be deployed each morning. This obviously means that deploying and configuring your system will need to be automatic.
  • Use tools such as VMWare, VirtualBox etc to manage your Virtual Machines.
  • Use tools like Puppet, Chef and Vagrant to automate the deployment and configuration of these VMs.
  • Add the deployment of the VMs to your C.I system!
  • If there are any randomly failing tests, which also randomly fail on your local machine, remove them or rewrite them to make them more reliable.
  • When doing sprint planning, make sure time is dedicated to investigating and fixing broken or flaky builds. It’s very important to ensure the Product and Project Managers are aware of the importance of the C.I. system, and the risk of not maintaining it properly.
  • Treat the rules of Continuous Integration as sacrosanct – if a build fails, fix it as soon as possible.

In an earlier post I wrote about the difference between having a Continuous Integration server and practicing Continuous Integration. If you start to get into the situation where you’re allowing broken builds to go un-fixed, you’re slowly slipping away from actually practicing continuous integration, and soon you’ll just be a development team who has a continuous integration server which is delivering much less value than it ought to.

*I may have got my chronology a little mixed up


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