Bug 1553372

Description of problem:
The ganglia gmond does not start under certain conditions.
"systemctl start gmond" will just block and not return, if it is executed not in multi-user.target:

[Unit]
Description=Ganglia Monitoring Daemon
After=multi-user.target

The gmond.service unit file should use network-online.target in order to avoid this situation:

[Unit]
Description=Ganglia Monitoring Daemon
After=network-online.target

This is also the default configuration of the unit file from upstream:
https://github.com/ganglia/monitor-core/blob/master/gmond/gmond.service.in

Version-Release number of selected component (if applicable):
ganglia-gmond-3.7.2-2.el7.x86_64

How reproducible:
Try to start gmond while not in multi-user.target, e.g. during operating system provisioning

Steps to Reproduce:
1. Install ganglia & ganglia-gmond
2. Run "systemctl start gmond" while not yet entered multi-user.target

Actual results:
systemctl start gmond will block and not return

Expected results:
gmond should be started

Additional info:
Problem encountered during deployment of new os installation.