Package power!

We often talk about pipe design and how to implement it in jenkins or other ci tools, that everything should be versioned and that everything should be tested all the time. These things are very important but something I didn't realize for quite some time was how important packaging is.

Our packaging was giving us problems.

Early on when building our continuous delivery pipe we where a bit worried about the number of artifacts we where spewing out of our pipe and the impact it would have on our nexus repo. So we did release our war and jar files into our repo but the final deliverable assembly we released was just a property file containing versions. These property files where used by our rudimentary bash deploy scripts. The scripts basically did a bunch of wgets to retrieve the artifacts from the nexus repo before deploying them. Yeah laugh you I now know how dumb this was.

Our main problem due to this was that our scripts where very delivery specific. For delivery Y we had components A, B and C while for delivery Z we had components A, D and E. We couldn't reuse things well enough so we had duplicates of our scripts. Another issue we had was that there was no portability in this what so ever. We didn't really make the connection between lack of packaging and our huge developer environment problems. Switching between working on delivery X and Z was tedious because we where managing the local deployments in eclipse with the JBoss plugin. It also required full understanding of what components needed to be deployed.

Manual tasks and a required high level of domain knowledge didn't make things easy for our new developers. In act it also made life a pita for our architects that develop less hours a week then the developers. For them the rotting of the development environment was a huge issue. Since all components where managed manually all had to be updated, built and deployed.

Inspiration and goals.

When me and my colleague where at QCon NY (awesome conf that everyone should try to attend) we listened to talks by Netflix and Etzy. We where totally blown away by two things. Etzy's practice that a new developer should code and deploy a production change on the first day and Netflix baking of images instead of releasing wars and ears. These where two of the main things we brought back with us and two things that we keep revisiting as we iterate our process.

Since we don't do continuous deploy we set the goal that a new developer should be able to commit a change that is ready for delivery on the first day. The continuous delivery part of the goal wasn't the problem since we already had that in place. It's the most obvious part of that goal. The next obvious task for us was that we really had to do something about our dev env setup. Then with some thought we realized that this wasn't enough we needed to do something about our entire on boarding process with mentoring and level of knowledge in the team. In order to mentor someone a developer needs to have a good understanding of most tasks in jira. At this stage this wasn't the case.

We made the knowledge increase our priority since this was biting us in many ways. I won't go much more into that. Then we tried to prioritize the setup of our developer environment but doing something about our deploy scripts ended up being a higher priority. This was a very good and honestly lucky decision. We knew how to do our deploy script changes and our production deployments where really more important. But we where also not sure how to do our developer environment changes so sleeping on it was what we decided, even though our devs where literally screaming in frustration.

Addressing the problems.

First thing we did when we started to rewrite our scripts was to sort out our packaging once and for all. We killed the property file and started using maven for everything. We had already been using maven to release all components and most configurations. But we where not using maven to package our final deployables and we where not using it to release our deploy scripts. We had already been made very well aware that we had to tie our deploy scripts to our deployable assembly. We changed both these things. We started to release everything and not just versioning everything. This imho is very important thing that's not mentioned enough. Blogs, articles and demos talk about versioning everything but not so much about the importance of actually releasing everything and treating each release as an artifact even if its "just" a httpdconf.

Once we started building these packages and setting our structure it was so clear how Netflix came to the conclusion that they should bake images. The package contains war files, config files, deploy scripts, liquibase scripts, custom JBoss control scripts, httpdconf, ect, ect. The more we package and the more servers we get in our park the more things we notice that we need to put into the package. Then it becomes even more obvious since we take this package and transfers it to tons of servers for different test purposes. Once at the server we run our deploy scripts that copy and link stuf into place on the server. Remind me why are we doing this over and over? Wouldn't it be better to just do this once and make an image out of it and mount this image on different nodes. Of course it would be, Netflix know what they are talking about! Most importantly it would bring the final missing pieces into the package JBoss, Java and Linux distributions. Giving us the power to actually roll out and test even OS patches through the same process as any other change. We arnt there yet, but the path is obvious and its nice to feel that what was once an overwhelming w000t is now a definite possibility.

So through a good packaging strategy we managed to improve and solve our deploy script problems. We now had one script to distribute and deploy them all! This also resulted in much fewer changes to the deploy scripts which in turn made them more stable. A lot of changes that previously required changes to deployment scripts now just requires a change to the packaging which makes the entire deployment process much more robust.

Portability!

Still though we hadn't solved our issues with our developer environments. I had the hunch for some time that our packaging could help us. Still it took us some time before we realized that we actually had created an almost fully portable deployment solution. Our increased maven usage had made us so portable that we could actually just write a simple script that combined the essence of the assembly job and the deployment job of our jenkins pipe into a local dev env script. By adding "snapshots true" to our maven version properties update we allowed our assemblies to be built including snapshots. Then we could just use our deploy scripts and voila our local JBosses and Mule ESBs where deployed with artifacts containing our code changes and most importantly our rebel.xmls, giving us full JRebel power with our production deploy scripts.

Our packaging strategy had made our continuous delivery process portable to our development environment allowing us to use the same assemble+deploy from local dev env to prod. Our developers now just need to know what assembly to deploy and they don't need to rebuild all included components just the ones they are currently working with, the others are added by maven for he nexus repo. So now our developers can quickly and easily switch between single component deploys and full deliveries.

Getting closer to our goals.

By adding JBoss & Mule installations to the script we further simplified the setup process for the new developers. We still have a few things we want to add to the script such as IDE install and initial source code checkout in order to simplify things further but at will have to rest it a bit since we have other higher priorities. Still we have taken huge steps towards our Etzy inspired goal of having new developers commit a code change on the first day.

It feels like all these levels of improvement have been unlocked by a good packaging strategy!

If its one thing I would change about the way we have gone by our implementation its the packaging. It's easy to say in hindsight but I'd really try to do it properly of the bat.