Showing posts with label Service. Show all posts
Showing posts with label Service. Show all posts

Friday, February 21, 2014

Scaling Continuous Delivery

Its been a while since I posted. Main reason is that we have been very focused on our main deliveries and feature development for the last six month. Whenever the feature train hits central station its always work such as build, release, test automation that gets hit first.

Though there are upsides to not touching your Continuous Delivery process for a few months. If you just keep working on your backlog you don't get time to analyze the impact of the changes you just made. Several times we have realized that the number two/three items in the backlog have dropped significantly in priority as we have fixed the most important issue and others rising fast in priority.

Now we have had time to analyse a lot of new issues and its time for us to pick up the pace again.

Scaling the Organization 

The good thing, the awesome thing (!) is that during these six or so months our organization has changed and we have actually be able to create a line organization that owns and takes responsibility for the continuous delivery process.

One of the major bottlenecks we found in our process was our platform/tools team. The team was small and resources in that team where always first to go when feature pressure increased. The team became just another "IT function" that didn't have time to be proactive due to all the reactive support work it had to do.

There was a few reasons behind this first it was the way the team worked in the past. It actually built the pipes and processes for all the teams by hand and tailored to the custom needs of each team. On some teams there were individuals who picked up the work and kept on configuring the jenkins jobs to tailor them even more but on some teams there was no interest whatsoever and their jobs degraded.

The result of this was that no one really knew how the pipes looked and how they should look. Introducing process change was a horribly slow process as it was all manual and dependent on the platform/tools team.

One of the first changes we made was to increase the bandwidth of the team and reducing the dependency on that team.  provided a great solution for this over a chat this summer. Instead of the platform/tools team supporting the development teams the development teams put resources into the platform/tools team. Each team was invited to add a 50% resource on a volunteered basis. This way the real life issues got much better attention in the platform/tools team and the competence about the Continuous Delivery process got spread in a much more organic way.

This did not eliminate the bottleneck organization but it gave us bandwidth to change the way we work and long term gave us the ability to scale with the number of teams that use the process.

Scaling the Process

The main issue with why we were a bottleneck was the way we worked. We preached Automate Everything, Test Everything, If its hard do it more often, ect but when it came to the Continuous Delivery process we didn't do what we where teaching.

We had ONE Jenkins Environment so all the changes happened directly in production. Testing plugins and new configurations on a production environment isn't really the way to delivery stability, reliability and performance.

Manually created Jenkins Pipes isnt really a way to create sustainable pace and continuous improvements.

Developing Deploy scripts without explicit unit tests isnt really a good way of creating a stable process. We have been priding ourselves with our deployment being tested hundreds of times pre production deploy which was true but very dumb. Implicit testing means that someone else takes the pain for my mistakes. Deployment scripts are applications and need to be treated as first class citizens.

This had to change.

First thing we did was to use the extra bandwidth we had obtained to build a totally new way of delivering continuous delivery. Automate everything, obvious, hu?

We also decided to deliver a continuous delivery environment per development team and not have them all in one environment. So we started with automating provisioning of Jenkins & Test environments. We dont have a cloud solution in our company at this time so we have a fake cloud that we work with which is a huge pool of virtual servers. This pool we provision and maintain using chef.

Second thing was to automate the build pipe setup. We built us a little simple pipe generator which has defined pipe templates of 5-8 different layouts to support the different needs. We actually managed to get the development teams to adjust to a stricter maven project naming convention to use the generated pipes as everyone saw the benefits of this.

The pipes we have are basically typed by what they build if its libs or deployable components and how they are tested as we still need to initiate our Fitnesse tests a bit differently from our other tests.

We made it the responsibility of the platform/tools team to develop the pipe templates and the responsibility of the development teams to configure their generator to generate the pipes they needed for their components.

Getting to this stage was a lot of work and a lot of migration work for all the teams but the results have been terrific. The support load has gone down alot on the platform/tools team and each bug fix is rolled out within minutes to all the pipes.

We have also be able to take on new development teams very easily. Not all teams in our company are ready to do Continuous Delivery but they are all heading in this direction and we can now provide environments and pipelines that match their maturity.


We have gone from a process developed as skunkworkz to Continuous Delivery as a Service within our organization. We always run into new bottlenecks and challenges this time the bottleneck was much more us than anything else. I assume that the next big bottleneck is going to be hardware and our inability to deliver on a cloud solution, since we now can roll out to more and more teams. But who knows I can be wrong only time will tell.

Sunday, February 24, 2013

Architect to re-Architect

We spend so much time trying to make the right decisions. It's one of the downsides of working on a next generation platform. "You better get it right this time!". We have all been there when a current generation solution just doesn't cut it anymore. Implementing that next requirement is going to be so expensive that we might just as well rewrite the whole thing. Thing is they also tried to "get it right this time!".

Why does it "always" go wrong? Why do we always run into dead ends with systems. Sure not always but always when an application is exposed to a lot of changes and new requirements.

Select technology then abstract and isolate it in the architecture.

Historically we have put a lot of thought into selection of technology when we build something new. Its important to not get it wrong so we think a lot about getting it right. We also think a lot about patterns so that we can replace tech A with tech B if the decision has to be reversed. Who hasn't written hundreds of DAOs so that we one day can change our database. How often do we change database? Historically well I have never done it. Change from Oracle to DB2 or what ever other SQL database has never been the reason for a major rewrite. In fact I've been part of more then one rewrite that has thown out everything but the data layer.

In the future we will see more database changes due NoSQL but if and when we do that do we really want to keep our DAO interfaces? If we do then we sure ant going to accomplish much with our rewrite. If we change then we change because we need to solve a bottleneck problem. In order to solve it we need to make an optimization using a niche product. So we need to write and query our data differently.

The cause of a major rewrite is either lack of scale ability or customer requirements that are to hard to expensive or too high risk to implement. The later almost always happens when everything has become so interconnected that the change can no longer be done in a safe and isolated way. We need to refactor so much I order to make the change possible that its cheaper to rewrite.

Distribute system can still be a monolith.

In standard monolithic design we monolithized everything not just the components of the system but also the data model and the business logic. By normalizing our data model and constantly striving towards decreasing code redundancy we entangle all the services of our application into a huge ball of concert. It's when we end up with our services entangled in a solid ball of concert that we need to blow it up, all of it in order to rewrite it. It doesn't matter how well we modeled our database, how nice our DAOs are or how much inversion of control we use. If we don't treat our services independently we will run into trouble down the road.

Decoupling the monolith into subsystems doesn't necessarily help either. If we still normalize our data and strive towards reusing as much code as possible within the components then all we have done is distributed the monolith. Chances are quite high that you will need to rewrite multiple components when the requirement change appears.

Lets take an example.

We have a training application aimed towards running and cycling. We have users, training sessions and races. Training sessions and races are the same thing really they both contain a number of users, equipment, time, distance and a route. We provide views of user training sessions, user races and race results by race. We sell the application to race organizers and its free to users. We have an agreement to keep the race results highly available and to keep all history of previous years.

So we have a simple data model with users and sessions with a many to many relationship and a type defining if its a race or a training session. Simple. Done. Delivered.

Now the application becomes really popular as a training application among users so we start gaining a lot of data. This data is mostly written since no one else then the user really cares about it. Though it does impact on our race data since people tend to look at that more.

Someone realizes that all the training data is interesting since we also added a heart rate integration. So we build queries on the training data to provide to medical studies. Sweet extra income that he sales dudes came up with. It's no real issue performance wise as we run them once a year and that's done over Christmas.

Now someone sells our services of race data, training and fitness trending to UCI (cycling union) as a tool for their fit against doping. We just need to add a query to correlate our sweet training reports with race results, how hard can that be. We add the develop for a sprint or two and go live. So now we get serious tonnage of data and we run our queries more often. *gag* it doesn't work we can't scale and we can't add e new query without totally killing our SLAs with the other races. We need to rewrite.

Components are not the silver bullet.

Components dont really help us
Having our system distributed into a user repository, session storage and a integration component providing rest services to our GUI component wouldn't help us all at much. Sure we have separated users and their equipment from the sessions but its the queries on the sessions that is the problem and that they are killing our SLAs with the other race organizers.

Design by Services 

So what we really need is to move the race result service into a service of its own. We need to isolate it. Even though all the data is identical to the race data by the user. Then we need to separate the integration code for the race organizer service into a service of its own so that we can deploy it separately.

Services do help us
Doing this when hitting then wall is both hard, costly and risky. Just the database split is a nightmare if the data has grown big.

If we would have done this from the get go we could just have re architected the user race and training session service. We could have moved that from our MySQL to a big table database or what ever without affecting our race by organizer service. But doing this upfront feels so awkward we would have had duplicate tables and redundant code.

Define and isolate services in the architecture.

If we focus on isolating services across our components instead of isolating technology then we can actually re-architecture our bottlenecks. In fact in our example we could just added a uci services that duplicates the other services and if it would run into performance issues we could just  re-architectured it. But that would have forced us to duplicate more upfront and to increase our initial development costs.
Services can be extremely similar and
yet be different services

It's hard to "get it right" when the right can be against everything you have been thought for years. What we must learn to understand better is how we define and isolate services so that we can re-architecture our bottlenecks for the services that experience them and not the entire system.