As a sysadmin, you probably deploy your bare-metal nodes through kickstarts in combination with pxe/dhcp. That's the most convenient way to deploy nodes in an existing environment. But what about having to remotely init a new DC/environement, without anything at all ? Suppose that you have a standalone node that you have to deploy, but there is no PXE/Dhcp environment configured (yet).
The simple solution would be to , as long as you have at least some kind of management/out-of-band network, to either ask the local DC people to burn the CentOS Minimal iso image on a usb stick, or other media. But I was in a need to deploy a machine without any remote hand available locally there to help me. The only things I had were :
- access to the ipmi interface of that server
- the fixed IP/netmask/gateway/dns settings for the NIC connected to that segment/vlan
One simple solution would have been to just "attach" the CentOS 7 iso as a virtual media, and then boot the machine, and setup from "locally emulated" cd-rom drive. But that's not something I wanted to do, as I didn't want to slow the install, as that would come from my local iso image, and so using my "slow" bandwidth. Instead, I directly wanted to use the Gbit link from that server to kick the install. So here is how you can do it with ipxe.iso. image, add it as "virtual media" (and transfer will be fast, as that's under 1Mb), and boot the server.
Once it boots from the iso image, don't let ipxe run, but instead hit CTRL/B when you see ipxe starting . Reason is that we don't want to let it starting the dhcp discover/offer/request/ack process, as we know that it will not work.
You're then presented with ipxe shell, so here we go (all parameters are obviously to be adapted, including net adapter number) :
set net0/ip x.x.x.x
set net0/netmask x.x.x.x
set net0/gateway x.x.x.x
set dns x.x.x.x
ifopen net0
ifstat
From that point you should have network connectivity, so we can "just" chainload the CentOS pxe images and start the install :
initrd http://mirror.centos.org/centos/7/os/x86_64/images/pxeboot/initrd.img
chain http://mirror.centos.org/centos/7/os/x86_64/images/pxeboot/vmlinuz net.ifnames=0 biosdevname=0 ksdevice=eth2 inst.repo=http://mirror.centos.org/centos/7/os/x86_64/ inst.lang=en_GB inst.keymap=be-latin1 inst.vnc inst.vncpassword=CHANGEME ip=x.x.x.x netmask=x.x.x.x gateway=x.x.x.x dns=x.x.x.x
Then you can just enjoy your CentOS install running all from network, and so at "full steam" !
You can also combine directly with inst.ks= to have a fully automated setup.
Worth knowing that you can also regenerate/build an updated/customized ipxe.iso with those scripts directly too. That's more or less what we used to also have a 1Mb universal installer for CentOS 6 and 7, see https://wiki.centos.org/HowTos/RemoteiPXE , but that one defaults to dhcp
Hope it helps
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