Created attachment 1396646 [details]
journalctl -xe of epmd.service failing to start

Description of problem:

The systemd unit file /usr/lib/systemd/system/epmd.service specifies a limit on the forked processes count, LimitNPROC=1, which prevents the epmd service to start with a specific error (see the attachment). This later on blocks e.g RabbitMQ from starting.

I've cross-checked that replacing the executable of /usr/bin/epmd with /bin/true isn't affected by LimitNPROC=1 and most likely epmd indeed requires some forking to happen. I can't tell for sure as I don't know any Erlang :-/

This can be worked around with the minimal LimitNPROC=7 that worked for me in my Docker deployment. Better yet might be to omit the LimitNPROC altogether.


Version-Release number of selected component (if applicable):
erlang-erts-19.3.6.5-2.fc28.x86_64.rpm

How reproducible:
always

Steps to Reproduce:
1. install erlang-erts
2. sudo systemctl start epmd.service


Actual results:
epmd.service fails starting because it's limited to fork enough subprocesses.


Expected results:
epmd.service starts as expected

Additional info:

The systemd epmd.service unit file:

Unit]
Description=Erlang Port Mapper Daemon
After=network.target
Requires=epmd.socket

[Service]
ExecStart=/usr/bin/epmd -systemd
#ExecStop=/usr/bin/epmd -kill
Type=notify
StandardOutput=journal
StandardError=journal
DeviceAllow=/dev/null rw
PrivateTmp=true
#CapabilityBoundingSet=
NoNewPrivileges=true
Restart=always
LimitNPROC=1
LimitFSIZE=0
User=epmd
Group=epmd

[Install]
Also=epmd.socket
WantedBy=multi-user.target