[stouset]

My interpretation of the GP was that a code change in one node can be automagically propagated out to a cluster of participating Erlang nodes.

As a security person, this seems inherently dangerous. I asked why it is safe, because I presumed I’m missing something due to the lack of ever hearing about exploitation in the wild.

[toast0]

An Erlang dist cluster has no barriers between connected nodes. But a multithreaded application has no barriers between its threads either.

If someone can exploit one Erlang node, they can easily take over the cluster. But in a more typical horizontally scaled system, usually if they can get into one node, they can get into all the other nodes running the same software the same way.

Security wise, I think of the whole cluster as one unit. There's no meaningful way to separate it, so it's just one thing. Best not to let anyone in who can't be trusted, because either they have access or they don't; there's no limited access.

But given that, may as well push code updates over dist in a straight forward way, because it's possible, so it may as well be straight forward.

[badpenny]

Why is it any more dangerous than a conventional update, which also needs to be propagated?

[stouset]

A conventional update takes place out of band.

If someone were to exploit a running Erlang process, the description of this feature sounds to me like they would have access to code paths that allow pushing new code to other Erlang processes on cooperating nodes.

[vermilingua]

Yes, but if they can exploit one process they can exploit any of the other nodes anyway, so there's nothing to be gained but a bit of convenience.