The era of applications: microservices and containers in the cloud

It’s finally time to turn the page. We’re now right into the era of applications. They now are dictating how the rest of the world of IT should behave. Infrastructure has no longer the spotlight but it’s taking the passenger’s seat and merely delivering what it’s being asked for. What I sort of predicted almost 3 years ago in “Why the developer cloud will be the only one” is now happening.

That’s no good news for someone in this industry, I know. It’s much easier to talk (and sell) dumb CPU, RAM, storage space than it is about continuous integration, delivery, runtimes, inherently resilient services or even things like the CAP theorem. Sorry guys, if you want to remain in this industry, it’s time to step up and start understanding more about what’s happening up there, at the application level. Luckily, we have things that help us do so. Things like thenewstack.io (cheers @alexwilliams and team) who’s doing an awesome job introducing and explaining all these new concepts to the wider audience (including me!).

And to learn more about this phenomenon is also why I am going to attend KubeCon in London next week. For those who don’t know, KubeCon is the conference of Kubernetes, a Google-stewarded project for containers orchestration and scheduling. Some people will say it’s just one out of many right now but for us, at Flexiant, it’s just *the* one, as it possess the right level of abstraction to deliver container-based distributed applications. I’m going there to listen to industry leaders, innovators and just anyone who’s fully understood the new needs and who’s working every day to solve these new problems in new ways.

If you still don’t know what I’m talking about, read on. I’m going to take a step back and tell you a bit more about the drivers that caused applications to take over and why we needed different architectures, such as microservices, to be able to efficiently deliver and maintain that software that’s eating the world. If you’re short of time, you can simply watch the embedded video at the top of the page which should tell roughly the same story.

TL;DR

Software is now pervasive in people’s everyday’s life and it’s handling many of the new business transactions. Application architectures had to evolve in order to be able to cope with the increase in demand. Microservices is the optimal software architecture that combined with cloud infrastructure and containers can successfully fulfil new application requirements.

However, its numerous advantages are counter balanced by an increased complexity, which requires new orchestration tools that are able to join the dots and hold a global vision of how things are going. To achieve this, orchestration needs to happen at a higher level of the stack than what we had been previously seeing in the previous infrastructure era.

The rise of microservices

We can comfortably acknowledge how the way we do business has changed, how we see more and more transaction happening just online and how software is the only mean to achieve them. Software that, by the global nature of the relationships, needs to cope with a large number of users. It also needs to constantly deliver performance, to satisfy its user base as well as new features to keep up with competition, serve new needs and unlock new opportunities. You can easily understand how the traditional way of developing applications could just not power this kind of software. Monolithic applications were just too hard to scale, slow to update and difficult to maintain; on the other hand, the recently hyped PaaS was just too abstracted (compromising on developers’ freedom) and expensive to deliver the required efficiency.

That’s when microservices came in as the new preferred architectural pattern. Of course they had been around for a while even before they were called so but, as Bryan Cantrill (@bcantrill) said “[…] only now that we gave a name to it, it has been able to spread much beyond that initial use case”. That means that whenever we manage to label something in IT, this helps with diffusion, adoption and it serves as a baseline for further innovation. This has happened with cloud computing, and we see this happening again. For once, thank you marketing!

What exactly are microservices? We call microservices a software architecture that breaks down applications into many atomic interdependent components that talk to each other using language-agnostic APIs. A single piece of software gets broken into many smaller components, each of them publishing a API contract. Any other piece of that application can make use of that microservice just by addressing its API and without knowing anything about what’s behind it, including which language it’s written in, or which software libraries it uses. That unlocks a number of benefits, like single components that can be developed by different people, shared, taken from heterogeneous sources and reused a number of times. They can be updated independently, rolled back or grown in number whenever the application as whole needs to handle more workload. All of this without having to tear down the giant, heavy and slow monolith. Sounds great? Thumbs up.

Infrastructure for microservices

Setting up the infrastructure to host such distributed, complex and ever changing software architectures would be a real challenge, if we did not have cloud. In fact, infrastructure-as-a-service is a just no brainer to host microservices. Why? Because it provides commodity infrastructure, because you pay for what you use, because it’s just everywhere near your end users and because it never (well, almost) runs out of capacity. But what makes it so perfect for microservices is its programmability, required whenever a distributed application needs to deploy and re-deploy again and again, while adapting its footprint to its workload requirements at any given moment. We couldn’t have done it with traditional data centre software. Full stop.

When people think of IaaS, they think about virtual machines, virtual disks and network. Let’s call it traditional IaaS. And if you look at it, it’s not really fit for purpose for what we described above. In fact, virtual machines have zero visibility of what’s going on on top of their OS, let alone the interdependencies with other virtual machines hosting other services! So, we’ve seen things like configuration management systems (Chef, Puppet, Ansible, etc) taking over this part and, at the completion of the OS boot, to execute a number of configuration tasks to reach the full application deployment. It sort of worked so far, but at what price? First, virtual machines are slow. They need to be commissioned and then full OS needs to come up before it can execute anything. We’re talking about 20-30 seconds if it’s your lucky day up to several hours if it’s not. Second, virtual machines are heavy. The overhead that the hypervisor carries is just nonsense, as well as all that other multi-process and multi-user functionality that their OS was born to deliver, when in reality they simply need to host a little – micro – service. And configuration management systems? Even slower. Let alone their own weight (I’m looking for example at the full Ruby stack with Chef) they typically rely on external dependencies that, unfortunately, can change and generate different errors every time they are called in.

There was the need for something better. Oh wait, we already had something better! Containers. They existed for a while but they were having a seat in the previous infrastructure-centric IT world that was dominated by the expensive feature-full virtual machines. Guess what, containers understood (yeah, they apparently have a thinking brain!) that they could make the leap into the new application-centric world and shake hands to software developers. That’s how they recently become – rightly so – popular, as I wrote before in “The three reasons why Docker got it right”. Containers are just right to host microservices because (1) they’re micro as well, and they can start in a fraction of a second, (2) they’re further abstracted from the infrastructure and hence have no dependency on the infrastructure provider, (3) they are self-contained and don’t rely on external dependencies that can change but, most importantly, they are immutable. Any change within the container configuration can trigger the re-deployment of a new version of the container itself, which then can be rolled back if the result is not what we were expecting.

New challenges for new opportunities

As it happens every decade or so, the tech world solves big problems by tackling them from the side with disruptive solutions that unlock tremendous new opportunities. The veterans of this industry see these solutions and think “wow, that’s the right way of doing it!”, no question. However, new approaches typically also open up to a number of unprecedented challenges that could not even exist in legacy environments. These new challenges demand new solutions and that’s where the hottest (and most volatile) startup scene is currently playing a game.

Kubernetes, Docker, Mesos and all their eco-systems are right there, trying to overcome challenges that arise from the multitude of microservices that need to operate independently (providing a scalable and always available service) as well as with each other, cooperating to make up the whole application’s business logic. Networking challenges coming from microservices that need to communicate in a timely, predictable and secure way over the network. Monitoring challenges as you need to understand what’s going on when an end user presses a button, if any of the components is suffering from performance and needs to be scaled. And not to forget organisational challenges that come from when you potentially have so many teams working together on so many independent components that involve security, adaptability and access control, to name a few.

In the end, as we can’t stop software from eating more pieces of the world, we simply can try to improve its digestive system. Making software transparent to end users to generate positive emotions and ease transactions, while helping businesses not to miss any opportunity that’s out there are the ultimate goals. Making better software is a just a mean to get there and microservices, cloud and containers are headed in that direction. See you at Kubecon EU!

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