Description of problem:
ipa-otpd is a service that is ran on-demand. Normally Dirserv breaks idle connection after some timeout, and ipa-optd fails, then starts again if needed.

It seems that it can't get it's socket to start in this installation:

Apr 17 12:57:49 ipa-ba1.ipa.orange.sk systemd[1]: ipa-otpd.socket: Failed to queue service startup job (Maybe the service file is missing or not a template unit?): Resource temporarily unavailable
Apr 17 12:57:49 ipa-ba1.ipa.orange.sk systemd[1]: ipa-otpd.socket: Failed with result 'resources'.

[root@idm0 slapd-AGDSN-DE]# sd status ipa-otpd@62-848960-0.service
● ipa-otpd@62-848960-0.service - ipa-otpd service (PID 848960/UID 0)
Loaded: loaded (/usr/lib/systemd/system/ipa-otpd@.service; static; vendor preset: disabled)
Active: failed (Result: exit-code) since Wed 2021-03-31 21:29:58 UTC; 1min 1s ago
Process: 2322932 ExecStart=/usr/libexec/ipa/ipa-otpd $ldap_uri (code=exited, status=1/FAILURE)
Main PID: 2322932 (code=exited, status=1/FAILURE)

Mar 31 21:28:58 myhost ipa-otpd[2322932]: LDAP: ldapi://%2fvar%2frun%2fslapd-AGDSN-DE.socket
Mar 31 21:28:58 myhost ipa-otpd[2322932]: lukasjuhrich@AGDSN.DE: request received
Mar 31 21:28:58 myhost ipa-otpd[2322932]: lukasjuhrich@AGDSN.DE: user query start
Mar 31 21:28:58 myhost ipa-otpd[2322932]: lukasjuhrich@AGDSN.DE: user query end: uid=lukasjuhrich,cn=users,cn=accounts,dc=agdsn,dc=de
Mar 31 21:28:58 myhost ipa-otpd[2322932]: lukasjuhrich@AGDSN.DE: bind start: uid=lukasjuhrich,cn=users,cn=accounts,dc=agdsn,dc=de
Mar 31 21:28:58 myhost ipa-otpd[2322932]: lukasjuhrich@AGDSN.DE: bind end: success
Mar 31 21:28:58 myhost ipa-otpd[2322932]: lukasjuhrich@AGDSN.DE: response sent: Access-Accept
Mar 31 21:29:58 myhost ipa-otpd[2322932]: bind.c:088: Input/output error: IO error received on bind socket
Mar 31 21:29:58 myhost systemd[1]: ipa-otpd@62-848960-0.service: Main process exited, code=exited, status=1/FAILURE
Mar 31 21:29:58 myhost systemd[1]: ipa-otpd@62-848960-0.service: Failed with result 'exit-code'.

Version-Release number of selected component (if applicable):

systemd-219-42.el7_4.10.x86_64
ipa-common-4.5.4-10.el7_5.1.noarch

How reproducible:
on clients side - always, could not reproduce in lab

Actual results:

Expected results:
ipa-otpd restarts succesfully

Additional info:
sosreport can be found in the attached case

As I consulted with IPA dev team, this needs to be investigated from systemd side. If it's IPA's bug - please revert it to IPA. Thank you!