Jun 2018: Disclaimer - it’s mid-2018, and “Cloud” started a long time ago. Many years ago. I know this; I’m a relative latecomer to the party. Here, then, I don’t pretend to champion something new and bleeding edge - I’m just presenting my own thoughts as I gaze from the near-bottom of the learning curve and strap my climbing gear on!
Setting the Scene
Right now AWS is very much an established player, but Kubernetes - Greek, from which “Governor” and “Cybernetic” both stem, apparently, which is apt - is increasingly being lauded as the “winner” in the containers arena, and quite plausibly.
My take: AWS offers a rich - overwhelming to the newcomer? - set of out-of-the-box services, true to the longstanding vision of technology being comprised of “building blocks” which one combines to form overall “solutions”, or systems. AWS is doing very well, it’s widely used, widely respected, and is building up traction in one key area: the job market, where ads in my part of the world often indicate its use.
Much of the industry buzz however seems to be around containers, with Docker, Kubernetes and the Cloud Native Computing Foundation being well at the forefront. Indeed AWS and other providers more “Platform as a Service” than “Infrastructure as a Service” are all also making sure they support Docker and containers.
The upshot is, no matter which provider you’re working with, containers are pretty hot right now.
“Containers” is a new thing to me; I’ve been working with physical servers and VMs for the past 20 years, and I’ll freely admit that term pretty much crept up on me. And looking online for “Explain Like I’m 5” explanations yields a lot of stuff from people that have plainly never spoken to a 5 year old.
I’m really not up on the finer points but like much in the world of technology a rough abstraction/concept perhaps suffices for now: I think of them as ultra-lightweight alternatives to VMs - but they are still “virtual instances”. A container though doesn’t have the full weight of say a Windows or Linux OS inside it, rather it stands apart and builds on the parent OS.
For example - and bear with me, consider all this a rough sketch begging for correction - one could imagine deploying a system with apps running on 5 x 1Gb RAM VMs, 100Mb for “app” and 900Mb for “OS/kernel/etc”, total footprint being 5Gb. But imagine instead deploying 5 x 100Mb “app” containers on a host/parent with 900Mb: total footprint becomes just 1.4Gb.
This as far as I’m concerned is the big win: really small units of deployment where scaling up to 5, 10 or 50 container instances remains hugely efficient.
And that’s where the famous “Container Orchestration” phrase comes in: if one is to quickly, elegantly, safely ramp up and down large numbers of containers, one needs a bloody good set of usable and simple tools to handle that or one is going to make a right mess. Considering Kubernetes “The Guv’nor” makes a lot of sense in that regard.
Let’s say we have a super simple app that calculates a square root of a random number in an infinite loop. It’s easy to imagine that running in a little virtual world somewhere. It’s also easy to imagine we might want to run more of those neat little SqrtCalcer apps (“why” is another matter of course…). So, great, ramp the instances from 1 to 20. Easy.
But of course very few real world applications live in quite such a pure computation bubble: components need input, they produce output, they record changes, and they interact with their little component friends and even the wider world. And much of what “real world applications” pre-cloud and pre-container take for granted brings with it a set of challenges, not least durable file systems: when you can’t even write your log files to /var/tmp with any guarantee they’ll survive the night you need to find alternatives. If the promise of containers is super-simple create, destroy and scale-up/scale-down, it becomes clear that one mustn’t rely on any one running container to be anything more than some transient borrowed processing power.
Same for database access: sure you can run a database server on a larger-sized container, but you need to park your data somewhere, and that somewhere needs to be reliable, available, durable, etc.
Networking and security considerations come into play: how do containers talk to one another? What manages them and how? How is data from and back out to the wider network handled? How are communications secured, in terms of both authentication and authorisation?
I won’t go into too much depth in this brief piece, but it should be clear that additional support is needed here: to gather and make available output logs; to coordinate lifecycle events (start, stop, etc) for containers; to provide the durable storage we need in so many areas. And that extra support pretty much directly implies extra complexity, really it can’t not mean extra complexity.
Systems Engineers vs Application Developers
DevOps, Full Stack Developer: trends that I think ride roughshod over the fact that - very often - people enjoy working on one part of technology rather than others, and their strengths develop accordingly. I’ve often worked in groups where the demarcation between application developers, system engineers, and DBAs is very clear, and I’ve found it has worked well.
Sure, “specialisation is for insects”, but every single one of those engineering disciplines is potentially large and complicated enough for one person to immerse themselves in and devote an entire career to mastering. One does not, contrary to the book publishing world’s view, master C++ development in 24 hours.
Some talented people seem able to execute well in all those areas, and well done to them but expecting most software developers - to whom writing a bug-free implementation of FizzBuzz remains a challenge, remember - to cover all those disciplines with any significant level of competence seems ill-judged, I would argue.
What’s my point? Simply that given the new complexities and challenges that running a multi-containered application involve are going to need a pretty special set of skills to get right. And I’m not sure it’s a set of skills that application developers necessarily have, or - once the lustre of the shiny and deeply fashionable new technology fades - actually really want.
What do I mean by that? Simply that for many application developers, job satisfaction comes from being immersed in a codebase; designing elegant, cleanly-coded classes or functions; choosing good processing algorithms or data structures; implementing complicated calculations with a deft simplicity; protecting data from accidental abuse; tracking down bugs with techniques honed from years of practice; choosing where to place logging outputs to allow maximum clarity of forensics and monitoring. The list goes on, and of course I don’t speak for anyone other than myself, but I hope it’s clear that Things Developers Find Rewarding and Things System Engineers Find Rewarding don’t necessarily overlap.
Application developers do of course need to design and build appropriately to their architecture: coding away, oblivious to a generally distributed architecture, isn’t really on.
Those Who Forget History…
…are famously condemned to repeat it. A lot of the container solution buzz right now reminds me of the J2EE, EJB situation nearly 20 years ago. The Entity/Session bean implementation of early 2000s was heavily flawed - ain’t hindsight great - but much vaunted by the industry at the time, and human nature being what it is, everyone in the Java ecosystem soon became convinced that EJBs on fully fledged J2EE app servers was the only way to go. Servlets? Pah. All in for EJBs!
So we all duly learned about EJBs. Chapter 1 of the Sun Microsystems guide pretty much warned us what was coming by talking about all the roles involved: developers, deployers, configurers. More or less: get your team of 60 together now folks, we’ve an application to build! And my God: they had the boilerplate XML to need it!
Long story short: over-complicated technology that most teams didn’t fully understand or handle well, leading to even simple CRUD apps being deployed in vastly over-architected distributed balls of mud that then ran like utter sludge (so everyone moved to Tomcat and Spring instead, and lived happily ever after; the end.)
Containers are not EJBs; the comparison only works so far. But some of the risks apply: people focus on using Docker and containers for their own sake, perhaps as a form of Resume Driven Development but more likely because we as a group just really do enjoy playing with new technology and we’ll often jump at the opportunity to do so - often losing sight though of the big picture: process efficiency, and ease of handling large scale and great swings in demand.
A Cambrian Explosion
We’re at a VHS vs Betamax point in time. Companies are fighting it out to see who will survive in this billion-dollar marketplace. Docker and Kubernetes and containers seem good technologies to bet on, but our industry tends to consolidate around a small number of big players, and right now there are a lot of parties involved in trying to end up being one of them.
At the end of the day cloud and container technology is there to help us efficiently solve real-world application and business problems. And for every discussion on Hacker News about the great gains realised, there’s one complaining about the time spent nursing a complicated deployment instead of building actual applications - and 20 more people then berating them for not using Cabbage or RatBagger or OoberScoober Container Magic or whatever other of the 10 OSS “supporting tools” has emerged this week (anyone else remember XDoclet? If you need tools to manage your tools, you’re just possibly doing it wrong…).
Some predict, and I happen to agree, that whatever ends up “winning” is likely to be based on Kubernetes but wrapping it in a way that makes it truly simple and accessible to the legions of time-pressured application developers to whom “secure-ftp helloworld.war to /home/produser/webapps on prod-server-emea-01” is the benchmark (and why not) for acceptable deployment complexity and overhead.
There is of course a tension there: the more proprietary one company makes its “wrapper”, the less “standard” it becomes, and lock-in, non-standard offerings may struggle to compete for that reason. Frankly, I’m quite glad it’s not my problem..!
This cloud business is evolving very quickly, but learning Docker, Kubernetes and general container concepts is a pretty good bet.
Be mindful that “system engineer” can be quite a different path to “application developer”. Don’t feel bad if you find you’d rather be coding and debugging large codebases or building elegant Web UIs than working with small scripts and connecting components - there’s a definite argument to be made that Kubernetes and related technologies are for the system engineers.
Watch carefully for signs any project you’re working on is veering towards an over-engineered EJB style mess; warning signs are:
it runs far more slowly than you all know, deep down, it really ought to
getting everything even up and running OK, and correctly communicating from one component to another, is difficult
making simple but nevertheless “across the whole application” level changes are inordinately expensive, e.g a new field on a core class or entity
no-one can work out what’s going on in terms of Request 123 making its way through the various components because the logging and tracing just isn’t there
Projects don’t finish on go-live day; in many ways that’s just the beginning. Make sure you are building something which can grow and change elegantly over 2, 5 or even 10 years.
Don’t be fooled into thinking that just because many teams are choosing certain technologies there aren’t better - sometimes simpler - alternatives!
I think the “summary of my summary” is really: look after yourself in this brave new world, enjoy the genuinely exciting new technologies, but watch out for the pitfalls!