Ypbind service fails to start on system bootup [race condition]

[Jakub]

Ypbind service does not start after system bootup.
The systemctl command reports that the nis is running, but there is no ypbind process on the system.

When I switch the ypbind to debug mode, I get following logs:

Jan 23 09:21:15 gklab-81-069 nis[743]: 796: parsing config file
Jan 23 09:21:15 gklab-81-069 nis[743]: 796: Trying entry: domain nis.igk.intel.com server 172.28.168.43
Jan 23 09:21:15 gklab-81-069 nis[743]: 796: parsed domain 'nis.igk.intel.com' server '172.28.168.43'
Jan 23 09:21:15 gklab-81-069 nis[743]: 796: add_server() domain: nis.igk.intel.com, host: 172.28.168.43, slot: 0
Jan 23 09:21:15 gklab-81-069 nis[743]: 796: Trying entry: domain nis.igk.intel.com server 172.28.168.170
Jan 23 09:21:15 gklab-81-069 nis[743]: 796: parsed domain 'nis.igk.intel.com' server '172.28.168.170'
Jan 23 09:21:15 gklab-81-069 nis[743]: 796: add_server() domain: nis.igk.intel.com, host: 172.28.168.170, slot: 1
Jan 23 09:21:15 gklab-81-069 nis[743]: 796: [Welcome to ypbind-mt, version 1.20.1]
Jan 23 09:21:15 gklab-81-069 nis[743]: 796: ping interval is 20 seconds
Jan 23 09:21:15 gklab-81-069 nis[743]: Cannot register service: RPC: Unable to receive; errno = Connection refused
Jan 23 09:21:15 gklab-81-069 nis[743]: 796: Unable to register (YPBINDPROG, YPBINDVERS, udp).

The system logs show that the nis tries to start before the rpcbind is initialized:

Jan 23 09:09:21 gklab-81-069 systemd[1]: Listening on RPCbind Server Activation Socket.
Jan 23 09:09:21 gklab-81-069 systemd[1]: Starting LSB: Start NIS client and server daemons....
Jan 23 09:09:21 gklab-81-069 systemd[1]: Starting RPC bind portmap service...
Jan 23 09:09:21 gklab-81-069 systemd[1]: Started RPC bind portmap service.
Jan 23 09:09:21 gklab-81-069 systemd[1]: Reached target RPC Port Mapper.
Jan 23 09:09:32 gklab-81-069 systemd[1]: Started LSB: Start NIS client and server daemons..

Adding the dependency to the nis systemd unit config solves the problem:
[Unit]
Wants=rpcbind.target

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: nis 3.17-34ubuntu3 [modified: etc/yp.conf etc/init.d/nis]
ProcVersionSignature: Ubuntu 4.4.0-59.80-generic 4.4.35
Uname: Linux 4.4.0-59-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.5
Architecture: amd64
Date: Mon Jan 23 12:08:29 2017
ProcEnviron:
 TERM=xterm-256color
 SHELL=/bin/bash
 PATH=(custom, no user)
 LANG=en_US
 LANGUAGE=en_US:
SourcePackage: nis
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.init.d.nis: [modified]
modified.conffile..etc.yp.conf: [modified]
mtime.conffile..etc.init.d.nis: 2017-01-23T09:31:48.928646
mtime.conffile..etc.yp.conf: 2017-01-20T09:44:39.706641

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Nish Aravamudan (nacc)]

Hello and thank you for filing this bug report! The ordering you mention does seem to be a real issue and I will add this to the server team backlog.

[David Britton (dpb)]

Hello there -- I checked on the latest dev release, booted it multiple times and didn't see any race, I then looked at the service, which already contains this fix:

# systemctl cat nis.service |grep rpc
After=rpcbind.target
#

I dug into the systemd.unit(5) which states in the 'Requires=' tag description (Requires= is a stronger version of Wants=) that 'After=' is what should be used when ordering is necessary. In fact, Requires= and Wants= will start services at the same time.

Since After= is already in the dev release, marking this issue fixed.