modifying epmd to look at the whole node name

Ulf Wiger ulf.wiger@REDACTED
Fri Aug 28 09:26:45 CEST 2009


Many years ago, I made a small patch in epmd to have
it look at the whole node name - not just the part before
the @. The reason then was that I wanted to be able to
test a distributed system by running all nodes on the same
machine and not change the node names.

Already today, you can start nodes using e.g.

erl -sname n@REDACTED
erl -sname n@REDACTED

and so on, but they can't talk to each other, partly
because epmd doesn't look at the host part (presumably
because it's always supposed to be the local host).

The other requirement for getting them to talk to
each other is to rig the name lookup, but this functionality
already exists.

I no longer have the epmd hack, and don't feel particularly
inclined to do it again. As far as I recall, I got it to
work, though.

It occured to me that this sort of functionality might be
interesting in a cloud environment too, where hostnames
are dynamic and may change over time. If the node name
could be kept constant, independent of the current host's
name, modifying only epmd and doing some inetrc trickery,
it might be possible to run a distributed mnesia database
in such an environment without having to worry about
persistent schema information becoming outdated when host
names change.

What am I missing?

BR,
Ulf W
-- 
Ulf Wiger
CTO, Erlang Training & Consulting Ltd
http://www.erlang-consulting.com


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