Relationship between snaps and containers, if any

[Loïc Minier]

Hi Luther!

Docker containers and snaps are different but sometimes overlap in solving
certain classes of technical problems. For instance, "software
distribution" as a broad problem is addressed by both snaps and Docker
containers, but with very different implementations.

First of all, yes you can run Docker on top of an all-snaps system such as
Ubuntu Core, and the Docker snap will also give you a Docker engine runtime
on Ubuntu classic.

Docker containers and snaps are built on different goals. Snaps will
typically look and feel like system or user apps running directly on your
regular system: you see them in the process list, they see each other if
the sandboxing allows it, they may interact with the screen/USB
devices/whatever if permissions allow it etc.. Docker containers feel more
like very efficient virtual machines that you connect to, they allow for
sandboxing as well – where the whole container is sandboxed – and for
resource quotas.

On your question of snapping a docker container: yes, you would be able to
wrap a Docker image inside a snap which would be a client of the Docker
snap.

On the top of my head, I can personally think of two main cases where you
would want to run containers on top of an all snap system: when your
workload is already packaged as a container, or when you want to use the
resource limits featured in Docker or LXD (e.g. limit network usage, CPU
usage etc.).

Cheers,
- Loïc Minier

On Wed, Jan 25, 2017 at 12:53 AM, Luther Goh Lu Feng <elfgoh at yahoo.com>
wrote:

> I seek clarity in understanding how docker containers are different from
> snaps. The question originated as I pondered if docker containers are the
> equivalent of snaps. Is there a blog post or FAQ somewhere that already
> addresses this?
>
>
> I also read this article[1], though dated, mentions docker support in
> Snappy, which makes me wonder:
>
> - the scenarios that I would want to deploy docker containers alongside
> snaps
> - snapping a docker container.
>
> Appreciate if someone can enlighten me. Thanks.
>
>
> -- Luther
> [1] http://thenewstack.io/snappy-ubuntu-a-new-cloud-os-with-
> support-for-docker-in-a-post-shellshock-era/
>
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-- 
- Loïc
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