Chapter 8. Booting hosts with the discovery image
The Assisted Installer uses an initial image to run an agent that performs hardware and network validations before attempting to install OpenShift Container Platform. You can boot hosts with the discovery image using three methods:
- USB drive
- Redfish virtual media
- iPXE
8.1. Creating an ISO image on a USB drive
You can install the Assisted Installer agent using a USB drive that contains the discovery ISO image. Starting the host with the USB drive prepares the host for the software installation.
Procedure
- On the administration host, insert a USB drive into a USB port.
Copy the ISO image to the USB drive, for example:
# dd if=<path_to_iso> of=<path_to_usb> status=progress
where:
- <path_to_iso>
-
is the relative path to the downloaded discovery ISO file, for example,
discovery.iso
. - <path_to_usb>
is the location of the connected USB drive, for example,
/dev/sdb
.After the ISO is copied to the USB drive, you can use the USB drive to install the Assisted Installer agent on the cluster host.
8.2. Booting with a USB drive
To register nodes with the Assisted Installer using a bootable USB drive, use the following procedure.
Procedure
- Insert the RHCOS discovery ISO USB drive into the target host.
- Configure the boot drive order in the server firmware settings to boot from the attached discovery ISO, and then reboot the server.
Wait for the host to boot up.
- For UI installations, on the administration host, return to the browser. Wait for the host to appear in the list of discovered hosts.
For API installations, refresh the token, check the enabled host count, and gather the host IDs:
$ source refresh-token
$ curl -s -X GET "https://api.openshift.com/api/assisted-install/v2/clusters/$CLUSTER_ID" \ --header "Content-Type: application/json" \ -H "Authorization: Bearer $API_TOKEN" \ | jq '.enabled_host_count'
$ curl -s -X GET "https://api.openshift.com/api/assisted-install/v2/clusters/$CLUSTER_ID" \ --header "Content-Type: application/json" \ -H "Authorization: Bearer $API_TOKEN" \ | jq '.host_networks[].host_ids'
Example output
[ "1062663e-7989-8b2d-7fbb-e6f4d5bb28e5" ]
8.3. Booting from an HTTP-hosted ISO image using the Redfish API
You can provision hosts in your network using ISOs that you install using the Redfish Baseboard Management Controller (BMC) API.
Prerequisites
- Download the installation Red Hat Enterprise Linux CoreOS (RHCOS) ISO.
Procedure
- Copy the ISO file to an HTTP server accessible in your network.
Boot the host from the hosted ISO file, for example:
Call the redfish API to set the hosted ISO as the
VirtualMedia
boot media by running the following command:$ curl -k -u <bmc_username>:<bmc_password> \ -d '{"Image":"<hosted_iso_file>", "Inserted": true}' \ -H "Content-Type: application/json" \ -X POST <host_bmc_address>/redfish/v1/Managers/iDRAC.Embedded.1/VirtualMedia/CD/Actions/VirtualMedia.InsertMedia
Where:
- <bmc_username>:<bmc_password>
- Is the username and password for the target host BMC.
- <hosted_iso_file>
-
Is the URL for the hosted installation ISO, for example:
http://webserver.example.com/rhcos-live-minimal.iso
. The ISO must be accessible from the target host machine. - <host_bmc_address>
- Is the BMC IP address of the target host machine.
Set the host to boot from the
VirtualMedia
device by running the following command:$ curl -k -u <bmc_username>:<bmc_password> \ -X PATCH -H 'Content-Type: application/json' \ -d '{"Boot": {"BootSourceOverrideTarget": "Cd", "BootSourceOverrideMode": "UEFI", "BootSourceOverrideEnabled": "Once"}}' \ <host_bmc_address>/redfish/v1/Systems/System.Embedded.1
Reboot the host:
$ curl -k -u <bmc_username>:<bmc_password> \ -d '{"ResetType": "ForceRestart"}' \ -H 'Content-type: application/json' \ -X POST <host_bmc_address>/redfish/v1/Systems/System.Embedded.1/Actions/ComputerSystem.Reset
Optional: If the host is powered off, you can boot it using the
{"ResetType": "On"}
switch. Run the following command:$ curl -k -u <bmc_username>:<bmc_password> \ -d '{"ResetType": "On"}' -H 'Content-type: application/json' \ -X POST <host_bmc_address>/redfish/v1/Systems/System.Embedded.1/Actions/ComputerSystem.Reset
8.4. Booting hosts using iPXE
The Assisted Installer provides an iPXE script including all the artifacts needed to boot the discovery image for an infrastructure environment. Due to the limitations of the current HTTPS implementation of iPXE, the recommendation is to download and expose the needed artifacts in an HTTP server. Currently, even if iPXE supports HTTPS protocol, the supported algorithms are old and not recommended.
The full list of supported ciphers is in https://ipxe.org/crypto.
Prerequisites
- You have created an infrastructure environment by using the API or you have created a cluster by using the UI.
-
You have your infrastructure environment ID exported in your shell as
$INFRA_ENV_ID
. -
You have credentials to use when accessing the API and have exported a token as
$API_TOKEN
in your shell. - You have an HTTP server to host the images.
When configuring via the UI, the $INFRA_ENV_ID
and $API_TOKEN
variables are already provided.
IBM Power only supports PXE, which also requires: You have installed grub2 at /var/lib/tftpboot
You have installed DHCP and TFTP for PXE
Procedure
Download the iPXE script directly from the UI, or get the iPXE script from the Assisted Installer:
$ curl \ --silent \ --header "Authorization: Bearer $API_TOKEN" \ https://api.openshift.com/api/assisted-install/v2/infra-envs/$INFRA_ENV_ID/downloads/files?file_name=ipxe-script > ipxe-script
Example
#!ipxe initrd --name initrd http://api.openshift.com/api/assisted-images/images/<infra_env_id>/pxe-initrd?arch=x86_64&image_token=<token_string>&version=4.10 kernel http://api.openshift.com/api/assisted-images/boot-artifacts/kernel?arch=x86_64&version=4.10 initrd=initrd coreos.live.rootfs_url=http://api.openshift.com/api/assisted-images/boot-artifacts/rootfs?arch=x86_64&version=4.10 random.trust_cpu=on rd.luks.options=discard ignition.firstboot ignition.platform.id=metal console=tty1 console=ttyS1,115200n8 coreos.inst.persistent-kargs="console=tty1 console=ttyS1,115200n8" boot
Download the required artifacts by extracting URLs from the
ipxe-script
.Download the initial RAM disk:
$ awk '/^initrd /{print $NF}' ipxe-script | curl -o initrd.img
Download the linux kernel:
$ awk '/^kernel /{print $2}' ipxe-script | curl -o kernel
Download the root filesystem:
$ grep ^kernel ipxe-script | xargs -n1| grep ^coreos.live.rootfs_url | cut -d = -f 2- | curl -o rootfs.img
Change the URLs to the different artifacts in the
ipxe-script`
to match your local HTTP server. For example:#!ipxe set webserver http://192.168.0.1 initrd --name initrd $webserver/initrd.img kernel $webserver/kernel initrd=initrd coreos.live.rootfs_url=$webserver/rootfs.img random.trust_cpu=on rd.luks.options=discard ignition.firstboot ignition.platform.id=metal console=tty1 console=ttyS1,115200n8 coreos.inst.persistent-kargs="console=tty1 console=ttyS1,115200n8" boot
Optional: When installing with RHEL KVM on IBM zSystems you must boot the host by specifying additional kernel arguments
random.trust_cpu=on rd.luks.options=discard ignition.firstboot ignition.platform.id=metal console=tty1 console=ttyS1,115200n8 coreos.inst.persistent-kargs="console=tty1 console=ttyS1,115200n8
NoteIf you install with iPXE on RHEL KVM, in some circumstances, the VMs on the VM host are not rebooted on first boot and need to be started manually.
Optional: When installing on IBM Power you must download intramfs, kernel, and root as follows:
- Copy initrd.img and kernel.img to PXE directory `/var/lib/tftpboot/rhcos `
- Copy rootfs.img to HTTPD directory `/var/www/html/install `
Add following entry to `/var/lib/tftpboot/boot/grub2/grub.cfg `:
if [ ${net_default_mac} == fa:1d:67:35:13:20 ]; then default=0 fallback=1 timeout=1 menuentry "CoreOS (BIOS)" { echo "Loading kernel" linux "/rhcos/kernel.img" ip=dhcp rd.neednet=1 ignition.platform.id=metal ignition.firstboot coreos.live.rootfs_url=http://9.114.98.8:8000/install/rootfs.img echo "Loading initrd" initrd "/rhcos/initrd.img" } fi