Re: [Nbd] nbd-server: about adding new exports dynamically

[Michael Richardson <mcr@...942...>]

>>>>> "nen" == nen  <Tuomas> writes:
    nen> We are using NBD server in a LTSP-environment to serve terminal
    nen> images. However, we'd like to add new images/exports dynamically, but
    nen> currently NBD server does not support it without full restart and
    nen> breaking all existing connections.

Yes, we had that problem too.

    nen> I've written a patch which simply re-reads all configuration files on
    nen> SIGHUP and if there was a export which was not previously in the
    nen> export/server array, it appends it and starts serving. It does not
    nen> alter any of the existing exports, it only adds new ones. In our
    nen> environment, this is to make it safe (non-destructive) to use. In our
    nen> environment, it is non-destructive operation, because we make sure
    nen> that we only add new configuration fragments to /etc/nbd-server/conf.d
    nen> and make no other configuration changes. However, in its current form,
    nen> it is not non-destructive in general, because it calls parse_cfile()
    nen> which in turn modifies global variables. In my opinion, parse_cfile()
    nen> should be refactored to make it side-effect free.

What I did was have our incremental script just start another nbd-server
instance with a specific config file from the conf.d itself...

    nen> Do you think the SIGHUP-based reconfiguration method is viable? If
    nen> not, what would be the better alternative?

I would like to have this kind of thing, but also think that perhaps the
parent server should/could be replaced with:
       for cfg in /etc/nbd-server/conf.d/*
       do
		nbd-server ..options..
       done


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