[Swlug] Docker, containers, oh my!

[Ben Tullis]

Hello all,

Here's an outline of my experience with Docker and some opinions as
well. I use it in production (at OpenCorporates) principally with Mesos
and Marathon (https://mesosphere.github.io/marathon/) for background
service management. Everything is running on-premise.
For this purpose we build docker containers from our Ruby on Rails
codebase and host these containers internally on our own instance of the
Docker Registry. Marathon is useful for us because it allows us to scale
particular background worker services in response to queue spikes or
planned workload increases.
Docker is also in use for our CI processes, with docker-compose being
used to run tests under Jenkins. This is very easy, but it could be done
with Vagrant or similar.
Finally we have a couple of instances were we just use docker-compose to
run some particular multi-service hosts because it's just easy to do so,
but in most of these cases we could have just chosen to use a VM.
We still use CM tools (Puppet) to provision Docker hosts and
manage config.
Lots of the responses on this thread have already highlighted the
gotchas, such as the union file system, the rapid changes to versions
and there are a bunch of issues that I ran into around cached file
systems layers, so I wouldn't say that it's made my life much easier,
but they're all still useful techniques and I cant see containers going
away any time soon.
We chose Mesos/Marathon some time ago and I will probably look at
Kubernetes as a replacement when I get a chance to review the setup. The
plethora of options around networking is what has put our development
team off so far. We also haven't implemented  service discovery yet, so
all of our containers are back-end processes that only make requests.
Front-end services still run on conventional VMs and load-balancers.
Best wishes,
Ben

--
Ben Tullis
tullis at hypothetical.co.uk


On Wed, 19 Apr 2017, at 04:19 PM, Matt Willsher via Swlug wrote:
> 
> Hi,
> 
> Whats your view on Docker (and container in general)?
> 
> Do you use it and if so to what degree? Has it made your liked easier?> 
>  If you don't use containers now are you looking to learn more
>  about them?> 
> 
> Matt
> 
> 
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