[erlang-questions] Interconnect question: how to work with names

[Dániel Szoboszlay]

The name of the Erlang node is the full thing, both the part before and
after the @ sign.
master@REDACTED and master@REDACTED and master@REDACTED are all
different nodes for Erlang.

It is a bit confusing that epmd only stores the part of the name before
the @. It is assumed that if you're talking to epmd on 127.0.0.1 or
myserver.l than all the nodes you find there will have 127.0.0.1 or
myserverl. in their name after the @ respectively. But this is of course
not necessarily holds, since there can be multiple names/IP addresses that
resolve to the same host.

So for example Erlang would believe master@REDACTED and master@REDACTED
are different nodes, in practice you cannot have both nodes running at the
same time, because they would both try to register as master in the same
epmd instance. (Using the loopback address in the node name can lead to
further complications when you have remote nodes in the cluster. E.g. you
can have debug@REDACTED connected to master@REDACTED when they're on
the same host, but if master@REDACTED would also connect to
master@REDACTED it would try to connect to debug@REDACTED on
myotherserver.l.)

On Fri, 28 Jun 2019 at 11:06, Max Lapshin <max.lapshin@REDACTED> wrote:

> myserver.l and 127.0.0.1  is the same server. I run it from this server.
>
> There is node  called "master" in epmd and I do not understand why I can
> connect to it via hostname: master@REDACTED and
> cannot connect to it via 127.0.0.1
>
>
> On Fri, Jun 28, 2019 at 11:53 AM Gerhard Lazu <gerhard@REDACTED> wrote:
>
>> My understanding is that you are opening a remote shell to a node with a
>> specific name.
>>
>> There is a node with name *master@REDACTED* on *myserver.l*
>>
>> There is no node with name *master@REDACTED <master@REDACTED> *on host
>> *127.0.0.1*
>>
>> On Fri, Jun 28, 2019 at 9:47 AM Max Lapshin <max.lapshin@REDACTED>
>> wrote:
>>
>>>
>>> I have server with hostname   myserver.l
>>> This hostname is in /etc/hosts and it is pingable
>>>
>>> I have master node running on it with:   erl -name master@REDACTED
>>>
>>> When I write software, I don't know what will be the hostname, so I write
>>> shell script for connecting to shell:
>>>
>>> erl -name debug -remsh master@REDACTED
>>>
>>> It fails:
>>>
>>> Erlang/OTP 21 [erts-10.3.5.2] [source] [64-bit] [smp:8:8] [ds:8:8:10]
>>> [async-threads:1] [hipe]
>>>
>>> *** ERROR: Shell process terminated! (^G to start new job) ***
>>>
>>> When I provide hostname, it works:
>>>
>>> erl -name debug -remsh master@REDACTED
>>> Erlang/OTP 21 [erts-10.3.5.2] [source] [64-bit] [smp:8:8] [ds:8:8:10]
>>> [async-threads:1] [hipe]
>>>
>>> Eshell V10.3.5.2  (abort with ^G)
>>> (master@REDACTED)1>
>>>
>>>
>>>
>>> What is the proper way to deal with this situation?
>>> I can see the master node in epmd names, I can connect to it, I can pass
>>> interconnect protocol.
>>> But I do not understand, why remsh doesn't connect to it.
>>>
>>>
>>> _______________________________________________
>>> erlang-questions mailing list
>>> erlang-questions@REDACTED
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>>>
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