Apparently the working julia version was moved into a stable channel since I
last looked at this, and the version in unstable is broken again. Fun!
Anyways, it builds again now (as part of parsons's config)
Pluto [1] is one of these interactive notebook thingies that have become
so unreasonably popular with people doing machine learning or data
analysis, but – somewhat surprisingly – it's actually not shit (e.g. no
global mutable state in the notebook, no weird unreadable fileformat
that doesn't play well with version control, etc.)
In particular, it can be used collaboratively (while it doesn't do
real-time collaborative editing like a pad, it /does/ push out global
updates each time someone executes a cell, so it's reasonably close),
and I think it may be useful to have for julia-hacking sessions.
It may also be useful for people running low-end laptops, since code is
executed on the host — and I guess hainich has enough unused ressources
lying around that we can spare a few.
After deploying this, the notebook server should be reachable via:
ssh hainich -L 9999:localhost:9999
and then visiting http://localhost:9999
Caveats: by design, pluto allows a user to execute arbitrary code on the
host. That is its main function, and not something we can prevent. I've
tried to mitigate this as far as possible by:
- only allowing access via ssh port forwarding. In theory pluto does
have basic access control, but that works via a secret link that
it'll spit to stdout on startup (i.e. the journal), which cannot be
set in advance, nor regenerted without restarting the entire process.
Unfortunately, this means we won't be able to use it at e.g.
conference sessions with people who don't have access to our infra
- running it in a nixos-container as its own user, so it should never
get any kind of access to the "main" directory tree apart from a
single directory that we can keep notebooks in (which is currently a
bind mount set to /data/pluto)
- limiting memory and cpu for that container via systemd (less out of
worry for exploits, and more so that a few accidental while-true
loops will never consume enough cpu time to noticebly slow down
anything else). The current limits for both a chosen relatively low;
we'll have to see if they become too limiting should anyone run an
actual weather model on this.
Things we could also do:
- currently, the container does not have its own network (mostly since
that would make it slightly less convenient to use with port
forwarding); in theory, pluto should even be able to run entirely
without internet access of its own, but I'm not sure if this would
break things like loading images / raw data into a notebook
- make the container ephemeral, and only keep the directory containing
the notebooks. I haven't done this since it would require
recompilation of pluto each time the container is wiped, which makes
for a potentially inconvenient startup time (though still < 3-5 mins)
Questions:
- have I missed anything important that should definitely be also
sandboxed / limited in some way?
- in general, are we comfortable running something like this?
- would we (in principle) be comfortable opening this up to other
people for congress sessions (assuming we figure out a reasonable
access control)?
Notes to deployer:
- while I have not tested this on hainich, it works on my own server
- you will probably have to create the /data/pluto directory for the
bind mount, and make it world-writable (or chown it to the pluto user
inside the container)
[1] https://github.com/fonsp/Pluto.jl/
