fix issue #1972: Stateless boot node looses network connection at dhcp lease expiration time;add NetworkManager in to rh7 diskless osimage pkglist

[immarvin]

fix issue:stateless boot node looses network connection at dhcp leaseexpiration time. #1972;
add NetworkManager in to rh7 diskless osimage pkglist

[zet809]

@immarvin From my point of view, if no NetworkManager installed, the CN can not even get a dhcp IP at all rather than lose IP 6 hours later since there is no dhclient run. So the dhclient must run at beginning, and then there is other reason that dhclient process is killed.

[immarvin]

hi @zet809 , the diskless node will get ip address on "service network start" without NetworkManager installed. "dhclient" is not run directly, it is triggered by either NetworkManager or network service. The difference between "NetworkManager" and "network" service is that dhclient process will be running as a child process of "NetworkManager" service, but will not be running after "network" service has been started.

[whowutwut]

I am ok with the changes in this pull request.

[whowutwut]

Actually, on 2nd thought, if you look at Matt's comment #1972 (comment), does it make sense to introduce NetworkManager into the compute nodes? It looks like some customers will change to static IP to reduce the dhcp from running on the compute nodes in production...

[immarvin]

hi @whowutwut , "dhcp" is the default option for user, we'd better make it work anyway. NetworkManager is just a new framework in redhat to manage network configuration instead of traditional "ifcfg-xxx" way. If customer want to configure static ip on diskless node, that can use the postscript "confignics -s".

There is some problem introduced by NetworkManager, see #104