[erlang-questions] reliably figure out hostname

Tim Watson <>
Thu Aug 2 10:17:32 CEST 2012


Any takers for this? I can't be the only person who's had to figure this out. The context is a distributed systems testing framework that needs to support resolving 'localhost' to a proper host name so the framework can become a hidden node and interact with the other erlang nodes It is testing against. Having to specify the real host name would make configuring the tool across different machines and development environments unpleasantly complicated so figuring out the right hostname is a boon in terms of keeping the configuration overhead down, but doing this for long names nodes is proving highly awkward.

Can anyone suggest a good portable solution?

On 31 Jul 2012, at 13:43, Tim Watson <> wrote:

> Is there a way to calculate the hostname reliably across platforms in Erlang? I have a non-distributed node that I wish to become a distributed node. Normally I call net_kernel:start([Name, shortnames]) and this is just fine. It also works with [Name, longnames] *sometimes and on some systems* - but other times it pukes. I've tried looking in the 'domain' or 'search' entries from inet:get_rc/0 but these are not always populated, even when dns config is clearly in place. I've also tried using 'inet_db:get_searchlist/0' but again, sometimes this returns [[]] but net_kernel:start([foobar, longnames]) doesn't work, whereas doing net_kernel:start([, longnames]) does.
> 
> Am I missing something incredibly obvious here? *is* there actually a simple way of determining what the proper fqdn for the machine should be, without breaking out to the os? I had even considered doing inet:gethostbyname/1 but again, the search domains entry seems to be empty, so I'd assume that -name foobar will work whereas in fact, -name  is required otherwise net_kernel won't start. 
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