[TriLUG] docker swarm, rancheros, persistent storage

[Dewey Hylton via TriLUG]

Here is a quick update (and bid for bumping this conversation in hopes someone
with more knowledge will see and respond):

Apparently the sshfs and chmod thing is a known issue, so I wasn't fighting my
own config or anything. But I also found out that sshfs does not provide needed
posix locking and other such things, so I cannot use that for the intended
project anyway.

So now I'm back to square one - hoping to hear from others who run docker in
swarm mode and have a working solution for replicated (or remote-mounted)
storage.

----- On Dec 19, 2017, at 3:11 PM, Dewey Hylton plug at hyltown.com wrote:

> Wow, not a lot of docker swarm folks here ...
> 
> I really like the idea of using https://hub.docker.com/r/vieux/sshfs/ as a
> volume
> plugin. Leveraging ssh makes me happy for more than one reason. And this does
> appear to work, at least on the surface.
> 
> I can create a volume (docker volume create -d vieux/sshfs ...) and see that the
> volume presents the proper data. For example, I can fire up a container with
> keisisqrl/fossil and see exactly what I would expect.
> 
> HOWEVER ...
> 
> If I attempt to create a service (docker service create ...) in swarm mode,
> using
> keisisqrl/fossil, even if on a single host and without being replicated, the
> container fails to start due to "chmod error" having to do with the very same
> volume.
> 
> So, going on the hope that other docker users are present and may have seen
> something
> similar, I'm posting this here. Anyone with a clue? Or failing that, capable and
> willing to help troubleshoot?
> 
> Thanks!
> 
> ----- On Dec 16, 2017, at 1:52 PM, Triangle Linux Users Group General Discussion
> trilug at trilug.org wrote:
> 
>> Hi all!
>> 
>> What do you use for replicated or shared persistant volumes for your docker
>> swarm containers?
>> 
>> Most folks who know me know that I'm a minimalist, sometimes (or most times) to
>> a fault. I'm currently working with RancherOS for my Docker-based projects. I
>> like it very much because it is very simple and stripped down - thus it fits
>> me. I can install via PXE, it seems to run Docker very well, etc. It also works
>> great in swarm mode. I happen to like swarm mode because it is baked into
>> Docker, secure by default (as in its management traffic is secured by TLS), and
>> it is very simple to get going - particularly when compared with Kubernetes.
>> 
>> Recently I have begun looking at moving some of my stateful containers into
>> swarm mode for redundancy. The theory is pretty simple; move the stateful data
>> into a named Docker volume which is accessible by all cluster nodes, and
>> therefore all containers. For external databases and such this is not a big
>> deal, but I have found this to be a pain point for simple shared files. For
>> example, a moinmoin wiki leverages plain files instead of a database; another
>> is the fossil cms, which can serve an entire directory of fossil repositories,
>> which are stored on the filesystem as sqlite database files. All this works
>> great in a Docker container, with data in a named volume - but I have yet to
>> figure out how to make those directories and files available to containers on
>> different hosts.
>> 
>> I have read that Kubernetes can provide those shared volumes somehow, but I'd
>> really like to find a decent way to do this without having to add so much
>> complexity. I've attempted NFS mounts (docker volume create --opt type=nfs) and
>> while the creation does not error out, and all swarm containers see the volume,
>> the volume data does not seem to reflect the data on the nfs share at all. I've
>> also attempted portworx, which sounds fantastic aside from its price tag for
>> enterprise users, but I have failed to get it installed properly. It may be
>> that both of these failures are somewhat due to the stripped-down nature of
>> RancherOS. If anyone has any experience with this, particularly with RancherOS
>> (not necessarily Rancher, though), I'd love to hear from you.
>> 
>> Even if you do not use RancherOS, and instead have a full installation of
>> something else (eg. Ubuntu/CentOS) with docker installed atop of that - and you
>> have figured out how to provide shared volumes across your swarm nodes - I
>> would appreciate hearing from you as well.
>> 
>> Thanks!
>> --
>> This message was sent to: Dewey Hylton <plug at hyltown.com>
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