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From Evan Dandrea ...@ubuntu.com>
Subject Re: Easy path to the latest Cassandra in Ubuntu
Date Wed, 29 Jun 2016 22:25:44 GMT
Thanks for following up, Dave, Michael, and Jonathan.

On Sun, 26 Jun 2016 at 11:04 Jonathan Ellis <jbellis@gmail.com> wrote:

> Is Snap a new packaging format like deb/rpm, or does it consume the
> existing deb package?
>

It's a new packaging format. Each application is isolated such that it
cannot see beyond its own filesystem (mounted squashfs plus writable
directory), make certain syscalls, etc.

It is not whole operating system isolation like docker and lxc, and there's
ongoing work to let you run snaps inside these containers:
https://github.com/lxc/lxd/issues/1952

That said, you can already run it just fine inside a cloud instance.


On Mon, 27 Jun 2016 at 09:59 Jonathan Ellis <jbellis@gmail.com> wrote:

> How would I deploy a cluster with Snap?
>

There's no native support for scaling out a single snap process yet, but it
can be accomplished by holding a little extra logic in the snap.

I'll look into this tonight using the Cassandra snap.


With the package I can pre-deploy my configuration to the node with cluster
> name, seeds, etc.  With Snap do I have to build a custom container to do
> that?  Or is there some way to pull in config from the host machine or a
> config server?
>

Today you'd build a container and call:
cat cassandra.yaml | sudo /snap/bin/cassandra.config-set cassandra.yaml

In the future there will be native support in snapd for setting config, and
I could see a path to that optionally being a pull rather than push
operation.


Aside: there's at 3 other reasonably popular projects called Snap; makes it
> hard to Google.
>

I've found this frustrating too. More documentation is being written under
the "snapcraft" branding, which should improve discoverability some.


On Sun, 26 Jun 2016 at 12:51 Dave Brosius <dbrosius@mebigfatguy.com> wrote:

> I notice that snapcraft.io already lists Cassandra as having a snap
> available on the front page.


Yes, I've already built and published a Cassandra snap [1]. I'd like to
prove that this is low maintenance enough that the Cassandra release team
could take over version bumping and publishing without being further
burdened.

1: https://github.com/evandandrea/cassandra-snap/


On Mon, 27 Jun 2016 at 10:15 Michael Shuler <michael@pbandjelly.org> wrote:

> I haven't played with snap at all, yet, so maybe Evan could elaborate,
> but building your own snapshots appears to be pretty straightforward.
>

If I understand the context you're applying to snapshots, that will be
specific to your container system / cloud. That said, new versions of snaps
unpack to new directories, and snapd lets you roll forward and back.


I'm not sure about hosting your own snap service, but I assume would be
> the way to go for customized deployments.


There's a centralised "store" for snaps, which is nice for app discovery.
If your deployment is locked down to not pull from the Internet, you can
run your own store:

http://blog.dustinkirkland.com/2016/06/howto-host-your-own-snap-store.html

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