[Swlug] Docker, containers, oh my!

James Tancock tanuck at gmail.com
Fri Apr 21 10:41:56 UTC 2017


Hi all,

Just to address your original message Matt - I’ve been using containers/Docker myself for 3+ years and in my current workplace (Moneyhub) we’ve been using containers in prod for over 2 years now. Has it made things easier? Definitely. We no longer have to worry about any state across vms or physical machines. We know that if it has a container runtime (Docker) on it, then we can deploy to it. It’s allowed us to give up using configuration management tools, which I’ve always found to be fickle beasts when they go wrong! But there’s definitely a cost. The barrier to entry is higher. Docker is a pretty unreliable product, every minor release tends to break something critical. And like you said, managing persistent storage is still a problem.

I don’t see what the problem with using containers in prod is though - Google have been doing it for nearly 10 years now. So have many others. So as a concept its obviously battle tested!

I agree with you on rkt though. It’s a much simpler proposition, far more unix like. Not like Docker with its client/server, ever changing api between the two, and not knowing which process is actually running your container. We’re hoping to have moved all of our containers to rkt soon!

My suggestion to anyone looking into this stuff though is go and look at the OCI (
https://www.opencontainers.org/
) and the Kubernetes API’s. As much as Docker don’t want to admit it, these are going to be the standards that everyone adopts in the container world.

James

Ps. I think this is my first time posting on this list - so Hi everyone!

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On Fri, 21 Apr 2017 at 10:53 Matt Willsher via Swlug

<
mailto:Matt Willsher via Swlug <swlug at mailman.lug.org.uk>
> wrote:

a, pre, code, a:link, body { word-wrap: break-word !important; }

Thanks for the feedback guys.

David - when you say in hindsight you chose the wrong technology with LXC, what do you mean?

My reasons for the original questions are that, in looking for a new role, I’m finding Docker mentioned a lot and it gives me some pause. I don’t actually think there is a lot wrong with the 'traditional’ packaging apps into an OS native format, using config management to set up a VM and deploy into that. I can see the theoretical benefits of Docker, but the extra overhead and complexity, security and storage matters seem like a time sink. 

I’ve dabbled with Docker in dev situations and built up a reasonably complex compose file that set up some home media components. I can see the appeal for large-scale environments where components need to be regularly updated as part of a scheduled release cycle, but issues around patching of the base containers and general workflow seemed rather nebulous. Abstracting away the underlying platform is appealing - all that’s needed in the runtime environment is a stock Docker OS (CoreOS, Atomic or Ubuntu seem the best candidates at the moment, but ), though the announcement of Dockers base OS is an interesting one.

I wonder if rkt will ultimately be the tooling of choice outside dev - it does away with the union filesystem, is more aligned to Kubernetes terminology, leverages other projects rather been an entirely self-contained eco-system as Docker is becoming. Though of course, they’ll recommend you run it on CoreOS :)

I  think 
https://thehftguy.com/2017/02/23/docker-in-production-an-update/
 and the comments there after raise a lot of good points.

Matt

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On 20 Apr 2017, at 10:27, David Goodwin via Swlug <
mailto:swlug at mailman.lug.org.uk
> wrote:

At $job-1 I built a hosting platform for (mostly) wordpress sites using LXC containers (with hindsight I chose the wrong technology - but at the time LXC seemed more mature with support for e.g. privilege separation).

I think it's hosting about 2500 sites now - spread over about 20 VMs.

So - they are "production ready".

But it does depend on the application(s). Deploying something like a standalone Wordpress site (minimal interdependencies) is quite different from a large bespoke application.

Container management/orchestration is still something that's being worked on. Kubernetes looks very promising.

Do you use it and if so to what degree? Has it made your liked easier?

Using it - Yes. But not entirely.

I makes it easier to deploy the application to live - as there's no "build a VM, install stuff onto it" stage...

David.

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