[erlang-questions] reliably figure out hostname

[Geoff Cant]

>From (hazy) memory, longnames are configured using
net_adm:localhost(). This differs from the local host name resolution
methods given in the thread in that it uses the contents of
'resolv.conf' (specifically the domain option) to construct the FQDN
from the hostname.

https://github.com/erlang/otp/blob/master/lib/kernel/src/net_adm.erl#L74


The last time I tried to write a reliable distribution based
start/stop/status control script, I'm pretty sure I ended up inspecting
the machine configuration, then manually starting distribution via
something like:

https://github.com/archaelus/egc_examples/blob/master/rescriptmsh#L6

to ensure that I would get the name I wanted. Unfortunately I don't have
permission yet to release the control script that implements all this.

Cheers,
-Geoff

Tim Watson <watson.timothy@REDACTED> writes:

> 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 <watson.timothy@REDACTED> 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([foobar@REDACTED, 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 foobar@REDACTED is required otherwise net_kernel won't
>> start.
> _______________________________________________
> erlang-questions mailing list
> erlang-questions@REDACTED
> http://erlang.org/mailman/listinfo/erlang-questions

-- 
Geoff Cant