Author Archives: Nigel Poulton

Docker on Windows: State of Play

Just a few *very quick* and typo-riddled thoughts on what I understand to be the state of play with containers on Windows. I’m basing this on a session I attended at Dockercon that had a John Starks from Microsoft talk about Windows and Cotnainer internals and also perform some demos.

First up….. it’s quite clear that the guys at Microsoft have done a shed-load of works to get things to where they are now. But the question is….. where are they now?

Hiding the mess

In my personal opinion… all of which could be totally wrong… is that there is a lot of fudging going on to make containers work on Windows.

For example, there’s this shim layer in between the Docker execution and the API interfaces into the Windows kernel. My understanding is that this is because a ton of the internal Windows stuff is gonna change over time – so why bother exposing all of the internal if you know they’re gonna be majorly rewritten soon. And that says to me that they’re doing a bunch of tactical stuff today. Probably in order to ship soon (soon in MS timescales).

Heavy containers

Kind of related… a shiny new Windows container will have a bunch of processes running inside.

The demo at Dockercon showed a couple of Windows containers – each running 19 processes – and both were on a base Windows container without an app running. This is glaringly different from a Linux container that usually has a single process. And I believe I’m right in saying that some of those 19 processes are *spare processes* for the container to use when it needs to create new ones…. Coz apparently it’s not possible to create a new process from within a container running on Windows – something to do with having to make RPC calls back to the host in order to perform certain basic system services (kinda like syscalls).

How does Windows build a “Container”?

Internally Windows has the notion of a “job”…. a collection of processes and resources those processes are using. To create a container, Windows takes this “job”, injects it with steroids, and calls it a “silo”. Think of a “silo” as a container. These “silo’s” get a bunch of namespaces and restrictions etc that aren’t too dissimilar to Linux namespaces and cgroups. E.g. Object namespaces are used to give each container (silo) its own C: drive.

Union filesystems

Not surprisingly, the way the native Windows filesystem (NTFS) works doesn’t make it easy to implement a union filesystem.  That’s not surprising considering the age of NTFS.  Though let’s not forget that AUFS never made it into the mainline Linux kernel – too many patches and too much of a mess.  So no disrespect to MS there.

What I did find surprising though was that there’s apparently nothing in the Windows storage stack that resembles device-mapper snapshots. Or I’m assuming there isn’t, as this would surely have been an option as a graphdriver – lets not forget that back in the day Red Hat wrote the devicemapper storage driver (graph driver) for Docker on Linux coz they couldn’t go with AUFS.

Anyway… MS has a workaround. I understood this to be a virtual block device on top of NTFS with symlinks. My *guess* is that this is not too dissimilar to Docker Linux using OverlayFS – a single writeable container layer on top of an image layer that is a bunch of directories with hard links. Don’t get me wrong here…. even if I’m right with my assumption you shouldn’t take the comparison too far (I do know that OverlayFS doesn’t deal with blocks etc).

Windows base images

Also…. every Windows Docker image will have to be built off one of two official Windows base images – Windows Server Core, or Windows Nanoserver.  And check this out…. for legal reasons neither can be hosted on Docker Hub!

Oh dear…. talk about politics getting in the way of engineering and innovation. C’mon Microsoft you’re doing so well!

On a side note, it does seem that Nanoserver is seen by MS as the default server platform to build against in the future. Makes sense to me as it seems like it’s gonna be a real server OS and not a desktop OS dressed up to look like a server OS.

Hyper-V containers

OK so Hyper-V contaienrs work like this – On a Windows server you spin up a Hyper-V container.  Windows then spins up a lightweight Hyper-V VM (sorta like boot2docker) and runs the container inside the Hyper-V VM. It seems to be a 1 Hper-V VM <> 1 container model.

Hyper-V containers also seem to be the direction that MS are going for folks who wanna run Windows containers on their laptops – basically saying Windows 10 won’t be offering native container support. Suppose this isn’t too different to boot2docker.

Final thoughts

All in all…. I was kinda disappointed. I’d genuinely hoped the implementation would’ve been cleaner. Though I don’t want to take away from the great work being done at MS. And let’s not forget that namespaces and the likes didn’t land in the Linux kernel overnight (not by a long-shot).

DISCLAIMER: Like I said at the beginning….. I reserve the right to be wrong about every single thing I’ve said above. It was the last seesion of DockerCon and my brain was dumping unwanted memories as fast as it could in order to take in more of what was being said… sadly my grey matter didn’t keep up as well as I’d have liked 😀

NOTE: I’ll add some pics later.

Enterprise Docker Discussion Group

I just created a new LinkedIn Group called “Enterprise Docker”.

Raison d’être: To discuss all things relating to Docker and container use in the enterprise!

So stuff like:

  • Who pays for Docker and container infrastructure in enterprises
  • What commercial support is available and what it’s like
  • What does the Docker ecosystem need to do better in enterprises
  • Basically anything else related to running Docker and containers in traditional enterprises

I’m no expert on the topic and think we’re at the very early days of Docker and containers in traditional enterprises…. so I’m hoping we can have a bunch of discussions and learn from each other.

Jump on over and get involved!


Hopefully the folks over at Doker Inc. don’t shoot me for modifying their logo…. it’s my cheap attempt to showing enterprises running on Docker 😉

Integrating Docker with Devops Automated Workflows

A few weeks ago I released a lightning fast (~1 hour) video course over at Pluralsight showing how to integrate Dockerized apps into a CI/CD automated workflow using some cool new features on Docker Hub.

Docker’s hot right. And we’ll be royally shafted if we don’t bring it under the control of our existing operational processes and the likes!  Think about it….. who wants tens/hundreds/thousands of Dockerized apps floating around in their estate unchecked? Not me!

Yes Docker’s the bizzo, yes Docker’s important, yes Docker’s blah blah blah. But unless we want a repeat of VM Sprawl and the headaches that brought,we need to get our act together over the reality of Docker and Dockerized apps.

Anyway…. the course takes a small web app + simple test, and shows how to push it through CI tests, integration with Docker Hub (build triggers, webhooks etc…..), and pushing to the world on Amazon Web Services!  All automated… and you’ll learn it all in a single hour! Sounds good to me!

Seriously….. if you don’t already have Dockerized apps in your estate:

  1. Go check again…. you actually might! Remember when we thought nobody was using AWS and then we learned about the whole shadow-IT thing…. Let’s not be caught sleeping at the wheel again.
  2. You will soon!  Seriously…. ignoring Docker aint gonna make it go away. So take a leaf out of the Scouting for Dummies book…. be prepared!

Anyway… that’s about it really… it’s a short fun course. And if you’re too tight-fisted to have a Pluralsight subscription, get one! they’ve always got a free 10-day trial going.

Production in the Cloud

This is my “Production in the Cloud” presentation form the recent TECHUNPLUGGED event in Amsterdam.

The skinny: It’s my opinion that public cloud services such as Amazon Web Services (AWS) and Microsoft Azure are ready for many enterprise production workloads. More than most of us think.

Sure…… there’ll be cases where they’re not a fit. But for those cases that are a fit….. you’d be hard pressed to find a more highly available and more world-class infrastructure to deploy on.

A few quick questions:

  • Do any of us really believe we can build better data centres than Amazon and Microsoft?
  • Do any of us really think we’re better at security than Amazon and Microsoft?
  • Do any of us really think we can build more highly available infrastructure than Amazon and Microsoft?

If you answered yes to any of the above…. then ask this final question…. can you do it at anywhere near the short term cost?

SaveTheTree – Docker in enterprises

First up…. this has nothing to do with saving trees – at least of the botanical variety. This has everything to do with Docker in the enterprise!


So… I spun up some new Docker hosts the other day… and it wasn’t long before I needed my trusty old friend `docker images –tree`. Well what was my horror when I got bitch-slapped with this:

npoulton@ip-10-0-0-90:/home/ubuntu$ sudo docker images --tree
 flag provided but not defined: --tree
 See 'docker images --help'.

Basically the `–tree` flag’s been pulled from the code! And yes, I know it’s been throwing “Warning: ‘–tree’ is deprecated” warnings at me since forever. I just never thought they’d actually go through with it.

And you know what right… I know it’s just a piece of software we’re talking about here.. but I’m seriously mortified by this. I don’t think I’ve ever had a more poignant lesson that it’s the litle things that make a big difference. Such a tiny command, that was so insanely powerful for Docker image management.

Enterprise Impact

Anyway…. what’s this all got to do with Docker in the enterprise?

Well…. I’ve spent enough time working big enterprises and financial services orgs that I know the odd ting about what gets signed off into production in these organizations and what doesn’t. So stick with me for a sec here…

Traditional enterprises – especially government, financial services etc – are as anal as the best of them when it comes to signing off code and services into production. Hell some of them still roll their own Linux kernels, not to mention still run stuff on AIX and pay through the teeth for EMC storage coz it makes them feel warm and fuzzy. Bottom line…. they soil their pants over every new thing they allow in to production.

So what I’m saying is….. if I was still at one of these types of orgs lobbying to get Docker signed off into production… I’d have taken the removal of `docker images –tree` as a steel-toe-capped kick in the old meat and two veg!

Why? Because now my ability to perform basic and vital image management tasks has become a whole lot harder. And the idea of running the folloing instead is just insane!

docker run --rm -v /var/run/docker.sock:/var/run/docker.sock nate/dockviz images -t

Now I’ve no personal issue with Nate Jones and his actually quite cool little image. But the thought that I might be able to run code like that – spin up a random container from some guy called Nate who I’ve never met – on production systems is just mind blowing!

I’m sure doing this kind of stuff is done all the time in cool hipster companies and the likes – and I’m totally cool with that. But it’s absolutely not done in rusty old enterprises with the kind of big fat wallets that I’m sure Docker would love to help thin out.

So what I’m saying to Docker is….. and I say this with the deepest respect to those involved with the Docker project (props to you all for the genuinely awesome work you do)…. but please add the `–tree` option back. And keep good image and container management capabilities within the trusted core Docker codebase. The code that folks like me are no doubt trying to champion into production environments all over the world!

#SaveTheTree 😀

Learn Docker this Summer – for FREE!

Seriously… I can’t think of a better thing to do for your career this summer, than learning Docker!

Docker Learner

Well….. my Docker Deep Dive course (don’t be put off by the scary title) is part of select group of online video courses that make up Camp Pluralsight – a bunch of video training courses that are free during summer 2015.  A cracking way enhancing your career prospects and learning cool new tech at the same time.

Seriously…. if you’re not up to speed with Docker, this course is for you! I genuinely think it’s the best way to get up to speed – I mean I honestly did everything I could to make this the ultimate Docker learning experience.

Anyway… pop on over to Pluralsight where the course is available to watch now…  The containers are coming… don’t be caught sleeping!

PS.  Below is some feedback I’ve had via Twitter – notice the comments that say how good it is for newbies!

Docker course praise

Why you should learn to program in Go…

Huh…. how come an infrastructure guy like me just produced a Go programming course for Pluralsight?

I’ll keep this brief… but I think Go is gonna be mahoosively important… I expect Go skills to be right up there as one of the most important skills for IT folks to have in the near future.

Anyway… three quick things to say.

First up… I started my IT life as FoxPro programmer back in ~1998. In fact I still hold a grudge against Microsoft for what they did to it. Anyway, my point is, I’m partial to a small amount of coding and thought it would be fun to create a course on the fundamentals of Go 😉

Second up… Oh – my – goodness! Go is like an amazing language. And you know what… I reckon poised to take over the world. Now I’m not about to say that the Linux kernel is gonna get re-written in Go.  But seriously… go check out the major infrastructure projects that are being written in Go these days! Just to name a few – Docker, most of the CoreOS stuff like etcd, fleet…, Google’s open sourced Kubernetes!

Whoooaaa! These are like the who’s who of game-changing new infrastructure technologies! Well guess what… they’re written mostly in Go. So I figured, if anyone wants to be really good at any of these techs, knowing Go would be massively helpful.

Third up… a ton of infra people are looking to acquire good plots of land in the new DevOps world. Well I reckon Go will be a cracking language to have in your suitcase if you’re planning the move to the brave new DevOps world.

OK… so what to expect from the course?

The key is in the word “fundamentals”. My aim was to give a good solid intro to most of the features of Go. Check out the course outline… but it’s basically – variables, functions, conditionals, loops, concurrency…. The idea being…. you’ll get enough of a theory + hands-on intro to take your interest further.

go TOC

That’s it really. Go check it out! As always, there’s a free trial that you can sign-up for in case you don’t wanna part with your hard-earned cash on a promise I made here – sign-up for the trial and then cancel if you don’t like what you see!

Linux + Containers + Go = 42

Containers: Resistance is Futile!

In April 2015 I delivered this talk at the inaugural TECH.UNPLUGGED event in London.

The presentation’s aimed at getting enterprises ready for the container revolution.

You can also check out the other talks from the event by checking out the TECH.UNPLUGGED YouTube channel

And……. if you’re wanting to get yourself and your enterprise ready for containers… check out my awesome Docker courses over at Pluralsight – and don’t forget to check out any tiral offers they have!

Learn Docker Swarm – Native Docker Clustering

So continuing my work around Docker and Linux containers, a week or two ago I published another Docker related course on Pluralsight.  This one’s titled “First Look: Native Docker Clustering“…..

The title kind of gives it away – it’ll get viewers up to speed with running a small clustered Docker infrastructure using Docker Swarm.  Now then, this course is only for people who want to be ahead of the curve….. If that’s not you, then you don’t need to read any further.

Wanna be ahead of the curve!

Still here? Magic.

Well I’ve not got a lot to say on this, other than I’m convinced that tomorrows infrastructure will be built around containers…. And a massive part of this future infrastructure is gonna be automation and orchestration etc. And clustering will be central.  I think we’re already at the point where core container technologies are understood and being deployed in production.  So clustering and orchestration etc are next….

Probably at scale we’re gonna be looking at things like Kubernetes and Mesos etc. But for out-of-the-box/batteries-included clustering, Docker Swarm is gonna be a good clustering solution.

So if you’re wanting to get into containers and position yourself well for the infrastructure revolution, get yourself up to speed with containers and orchestration!

In that space, Docker’s a good place to start.  But its not the only container technology out there – Rocket from the guys at CoreOS is great too (though very different).  Then there’s a whole bunch of next gen orchestration and clustering technologies like Kubernetes and Mesos etc.  All gonna be massively important in the very near future.  But before mastering those, you need and understanding of containers and be cool with them first.

Still need to learn Docker?

If you need to learn Docker I highly recommend my Docker Deep Dive course, also available on Pluralsight.  It’s a soup-to-nuts course that starts at the very bottom and explains and demos all core Docker features in detail, taking you beyond intermediate level.  If you don’t know Docker yet, I genuinely believe this is *the* best place to learn it.

blog image

I’d also recommend my Docker Swarm course.  Both courses are there for people who wanna play and work with awesome technologies that are changing the face of infrastructure IT.

Thanks for reading, and let’s go change the world!

Here come the *real* server Operating Systems…

The days of server and desktop Operating Systems looking and feeling the same are gone – those are the olden days!

We’re being invaded by a new breed of *proper* server Operating Systems.  These guys are stripped down, hardened, tuned and optimised for server workloads. They’ve got none of the extra crap needed for things like a slick desktop experience. No! These guys are designed and built to live in the data centre and the cloud and they look a lot different to their frilly desktop siblings.

Following in the footsteps of Android

Think about it like this…. Android is Linux. It runs a Linux kernel. But we accept that it’s waaaaay different to any Linux we run on a desktop or server. We accept that it’s highly tuned to run well on mobile devices, because…… mobile devices and the things we do with them are totally different to desktops!

Well guess what…… the same holds true for servers….. the things we do with servers are totally different to the things we do with desktops!

So it should only be natural that our server Operating Systems hugely differ from our desktop Operating Systems.

Let’s look at an example of one…..


Take a look at RancherOS announced a couple days ago (24th Feb 2015)…. this is a server OS in every respect.

NOTE: RancherOS is only one example. I’m also a fan of CoreOS. But things like Project Atomic from Red Hat and Snappy Ubuntu Core from Canonical are heading in this direction too.


For starters…. the RancherOS ISO is an impressive 20MB – yes that’s MB and not GB! Talk about a small attack surface, and small code-base that requires patching… I’m guessing there’s no unnecessary code in their – definitely no pretty GUI! All good stuff for a server OS.

Also…. pretty much everything on RancherOS runs inside a Docker container. And we’re not just talking about applications. We’re talking about system services too! Stuff like syslog, and ntpd all run inside of their own Docker containers.

If you want to learn Docker… check out my Docker Deep Dive course available on Pluralsight. You can even sign-up for a free 10 day trial that will allow you to watch the entire course!

That means that if you log on to a RancherOS box and list the running processes, you’ll see a bunch of kernel threads dressed up as processes (that’s normal) but you won’t see much more than that. There’s no init or systemd…. PID1 will be a special Docker instance for running system processes as containers.  So as well as no systemd,  there’s also no package manager, no GUI, no unnecessary fluff.  Basically, it looks and feels nothing like desktop Linux!


In my opinion….. this is all good stuff, and I love innovative stuff like this!

And it makes total sense…. servers are totally different beasts to desktop machines. I mean even Microsoft *started* to grock when it shipped Server Core. And well done to MS for finally shipping a server OS without a GUI. But the stuff going on in the Linux world is so far beyond that. We’re seeing massive changes for the cloud, automation, and container-based workloads.

The future’s bright… the future’s a new breed of minimalist, purpose-built, server Operating Systems!

NOTE: I’m not saying using Docker as PID1 or any of this stuff is production ready yet….. what I am saying though… is I love this kind of stuff and can see this kind of stuff being the future!