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Libvirt Virtual Hardware
CoreOS can be booted and configured on virtual hardware within a libvirt environment (under Linux) with different network services running as Docker containers on the docker0 virtual bridge. Client VMs or even baremetal hardware attached to the bridge can be booted and configured from the network.
Docker containers run on the docker0 virtual bridge, typically on a subnet 172.17.0.0/16. Docker assigns IPs to containers started through the docker cli, but the bridge does not run a DHCP service. List network bridges on your host and inspect the bridge Docker 1.9+ created (Docker cli refers to docker0 as bridge).
brctl show
docker network inspect bridge
Boot Config Service
First, run the bootcfg container with your configs and images directories.
docker run -p 8080:8080 --name=bootcfg --rm -v $PWD/data:/data:Z -v $PWD/images:/images:Z coreos/bootcfg:latest -address=0.0.0.0:8080 -data-path=/data -images-path=/images
or use ./docker-run.
PXE Setups
As discussed in getting started, there are several variations of PXE network boot environments. We'll show how to setup and test each network environment.
Several setups make use of the dnsmasq program which can run a PXE-enabled DHCP server, proxy DHCP server, and/or TFTP server.
PXE
To boot PXE clients, configure a PXE network environment to chainload iPXE. The iPXE setup below configures DHCP to send undionly.kpxe over TFTP to older PXE clients for this purpose.
With dnsmasq, the relevant dnsmask.conf settings would be:
enable-tftp
tftp-root=/var/lib/tftpboot
# if PXE request came from regular firmware, serve iPXE firmware (via TFTP)
dhcp-boot=tag:!ipxe,undionly.kpxe
iPXE
Create a PXE/iPXE network environment by running the included ipxe container on the docker0 bridge alongside bootcfg.
cd dockerfiles/ipxe
./docker-build
./docker-run
The ipxe image uses dnsmasq to run DHCP and TFTP. It allocates IPs in the docker0 subnet and sends options to chainload older PXE clients to iPXE. iPXE clients are pointed to the bootcfg service (assumed to be running on 172.17.0.2:8080) to get a boot script.
# dnsmasq.conf
dhcp-range=172.17.0.43,172.17.0.99,30m
enable-tftp
tftp-root=/var/lib/tftpboot
# set tag "ipxe" if request comes from iPXE ("iPXE" user class)
dhcp-userclass=set:ipxe,iPXE
# if PXE request came from regular firmware, serve iPXE firmware (via TFTP)
dhcp-boot=tag:!ipxe,undionly.kpxe
# if PXE request came from iPXE, serve an iPXE boot script (via HTTP)
dhcp-boot=tag:ipxe,http://172.17.0.2:8080/boot.ipxe
Continue to clients to create a client VM or attach a baremetal machine to boot.
Pixiecore
Create a Pixiecore network environment by running the danderson/pixiecore container alongside bootcfg. Since Pixiecore is a proxyDHCP/TFTP/HTTP server and the docker0 bridge does not run DHCP services, you'll need to run DHCP for your client machines.
The dhcp image uses dnsmasq just to provide DHCP to the docker0 subnet.
cd dockerfiles/dhcp
./docker-build
./docker-run
Start Pixiecore using the script which attempts to detect IP:port bootcfg ss using on docker0 or do it manually.
# Pixiecore
./scripts/pixiecore
# manual
docker run -v $PWD/images:/images:Z danderson/pixiecore -api http://$BOOTCFG_HOST:$BOOTCFG_PORT/pixiecore
Continue to clients to create a client VM or attach a baremetal machine to boot.
Clients
Once a network environment is prepared to boot client machines, create a libvirt VM configured to PXE boot or attach a baremetal machine to your Docker host.
libvirt VM
Use virt-manager to create a new client VM. Select Network Boot with PXE and for the network selection, choose "Specify Shared Device" with the bridge name docker0.
The VM should PXE boot using the boot config and cloud config based on its UUID, MAC address, or your configured defaults. The virt-manager shows the UUID and the MAC address of the NIC on the shared bridge, which you can use when naming configs.
Bare Metal
Connect a baremetal client machine to your libvirt Docker host machine and ensure that the client's boot firmware (probably BIOS) has been configured to prefer PXE booting.
Find the network interface and attach it to the virtual bridge.
ip link show # find new link e.g. enp0s20u2
brctl addif docker0 enp0s20u2
Restart the client machine and it should PXE boot using the boot config and cloud config based on its UUID, MAC address, or your configured defaults.