Store ssh connections in rails

Question

I have a rails app that needs to communicate with a couple of servers through ssh. I'm using the Net::SSH library and it works great. I would like however to be able to cache/store the ssh connections somehow between requests (something like OpenSSH multiplexing).

So, i can't store them in a key-value store like Memcached or Redis (because ssh connections are not serializable).

I don't want to store them in a session because they are meant to be used by all users (and besides i think it needs to be serializable also).

I managed to get this working with class variables and initiliazer constants. I know that class variables don't replicate between servers (in production), and i'm pretty certain initializer constants also don't. Something like:

initializer:

SSH = {}

model:

class Server
    def connection
        require 'net/ssh'
        SSH[name] ||= Net::SSH.start(ip, "root", :password => password)
    end
end

OpenSSH multiplexing would be great but i'm not sure if i could do that through the Net::SSH ruby library (i'm back to storing the master connection somewhere).

Are there any other solutions? Or if not, which one is the least evil of them all?

Answer 1

Perhaps rather than trying to share sockets across requests which is bound to end up causing pain and suffering you could delegate to a background processor of some kind? You could set up an ssh tunnel and use DRb to talk across it as if it was just a local network daemon, or any of the large number of networked asynchronous job handling daemons.

http://ruby-toolbox.com/categories/queueing.html

Answer 2

To keep the SSH connection up between requests, you'll need to spawn off a background process. The background process can open up a pipe or some other sort of interprocess communication method, the handle to which you can store in a serializable way.

Note that this is a non-trivial exercise, which is why I've only described it at high-level detail.