Comment # 1 on bug 1124947 from Matwey Kornilov

(In reply to Gabriele Santomaggio from comment #0)
> We are having several problems with the EPMD systemd service.
> 
> Often the epmd process is activated by an Elixir or Erlang process, this
> causes problems for other services that need Erlang as RabbitMQ.
> 
> 
> Here is a very easy way to reproduce the problem ( using
> openSUSE-Tumbleweed, but I can reproduce the problem also with other
> suse/open distributions):
> 
> ````
> vagrant init opensuse/openSUSE-Tumbleweed-x86_64
> vagrant up
> vagrant ssh
> ```
> 
> 
> Install rabbitmq:
> 
> ```
> sudo zypper in rabbitmq-server
> sudo rabbitmqct status
> ```
> 
> Check the EPMD:
> 
> ```
>  ps aux | grep epmd
> vagrant   3605  0.0  0.0  26820   216 ?        S    10:12   0:00
> /usr/lib64/erlang/erts-10.1.3/bin/epmd -daemon
> ```

First of all. Why are you running epmd from vagrant user? Probably, instead of
running epmd from systemd service you manually start another one instance which
ate required port number.

> 
> So, epmd is not running under systemd. 
> 
> Try to run RabbitMQ:
> 
> ```
> sudo systemctl start rabbitmq-server
> A dependency job for rabbitmq-server.service failed. See 'journalctl -xe'
> for details.
> ```
> 
> 
> does not start, because of:
> ```
> feb 11 10:29:09 vagrant-openSUSE-Tumbleweed systemd[3955]: epmd.socket:
> Failed to create listening socket: Address already in use
> feb 11 10:29:09 vagrant-openSUSE-Tumbleweed systemd[1]: epmd.socket: Failed
> to receive listening socket: Input/output error
> feb 11 10:29:09 vagrant-openSUSE-Tumbleweed systemd[1]: epmd.socket: Failed
> to listen on sockets: Input/output error
> feb 11 10:29:09 vagrant-openSUSE-Tumbleweed systemd[1]: epmd.socket: Failed
> with result 'resources'.
> feb 11 10:29:09 vagrant-openSUSE-Tumbleweed systemd[1]: Failed to listen on
> Erlang Port Mapper Daemon Activation Socket.
> ``` 
> 
> by killing "/usr/lib64/erlang/erts-10.1.3/bin/epmd -daemon"
> 
> it works
> ```
> ps aux | grep epmd
> epmd      3993  0.0  0.1  26820  1860 ?        Ss   10:33   0:00
> /usr/bin/epmd -systemd
> ``` 
> 
> Unfortunately, we have to deal with this problem in our OpenStack
> installations. 
> 
> 
> I know that the epmd service has been added to bind the epmd socket to
> localhost, but when it is not running inside systemd it is listening to all
> the network interfaces:
> 
> ```
> ss -tulpen | grep epmd
> tcp    LISTEN   0        128               0.0.0.0:4369     
>  ```
> 
> it is causing lot of problems during startup/upgrade RabbitMQ installations
> (also in OpenStack)
> 
> 
> proposal:
> Can we remove epmd.service ? 
> 
> I am/was also mainteiner for other erlang packages as:
> https://github.com/rabbitmq/erlang-rpm 
> Where we don't have anything about epmd, and also we don't have problems :)
> 
> Thank you