9.3. Adding compute machines to bare metal
You can add more compute machines to your OpenShift Container Platform cluster on bare metal.
9.3.1. Prerequisites
- You installed a cluster on bare metal.
- You have installation media and Red Hat Enterprise Linux CoreOS (RHCOS) images that you used to create your cluster. If you do not have these files, you must obtain them by following the instructions in the installation procedure.
9.3.2. Creating Red Hat Enterprise Linux CoreOS (RHCOS) machines
Before you add more compute machines to a cluster that you installed on bare metal infrastructure, you must create RHCOS machines for it to use. You can either use an ISO image or network PXE booting to create the machines.
9.3.2.1. Creating more RHCOS machines using an ISO image
You can create more Red Hat Enterprise Linux CoreOS (RHCOS) compute machines for your bare metal cluster by using an ISO image to create the machines.
Prerequisites
- Obtain the URL of the Ignition config file for the compute machines for your cluster. You uploaded this file to your HTTP server during installation.
- Obtain the URL of the BIOS or UEFI RHCOS image file that you uploaded to your HTTP server during cluster installation.
Procedure
Use the ISO file to install RHCOS on more compute machines. Use the same method that you used when you created machines before you installed the cluster:
- Burn the ISO image to a disk and boot it directly.
- Use ISO redirection with a LOM interface.
-
After the instance boots, press the
TAB
orE
key to edit the kernel command line. Add the parameters to the kernel command line:
coreos.inst=yes coreos.inst.install_dev=sda 1 coreos.inst.image_url=<bare_metal_image_URL> 2 coreos.inst.ignition_url=http://example.com/worker.ign 3
-
Press
Enter
to complete the installation. After RHCOS installs, the system reboots. After the system reboots, it applies the Ignition config file that you specified. - Continue to create more compute machines for your cluster.
9.3.2.2. Creating more RHCOS machines by PXE or iPXE booting
You can create more Red Hat Enterprise Linux CoreOS (RHCOS) compute machines for your bare metal cluster by using PXE or iPXE booting.
Prerequisites
- Obtain the URL of the Ignition config file for the compute machines for your cluster. You uploaded this file to your HTTP server during installation.
-
Obtain the URLs of the RHCOS ISO image, compressed metal BIOS,
kernel
, andinitramfs
files that you uploaded to your HTTP server during cluster installation. - You have access to the PXE booting infrastructure that you used to create the machines for your OpenShift Container Platform cluster during installation. The machines must boot from their local disks after RHCOS is installed on them.
-
If you use UEFI, you have access to the
grub.conf
file that you modified during OpenShift Container Platform installation.
Procedure
Confirm that your PXE or iPXE installation for the RHCOS images is correct.
For PXE:
DEFAULT pxeboot TIMEOUT 20 PROMPT 0 LABEL pxeboot KERNEL http://<HTTP_server>/rhcos-<version>-installer-kernel-<architecture> 1 APPEND ip=dhcp rd.neednet=1 initrd=http://<HTTP_server>/rhcos-<version>-installer-initramfs.<architecture>.img coreos.inst=yes coreos.inst.install_dev=sda coreos.inst.image_url=http://<HTTP_server>/rhcos-<version>-metal.<architecture>.raw.gz coreos.inst.ignition_url=http://<HTTP_server>/worker.ign 2 3
- 1
- Specify the location of the
kernel
file that you uploaded to your HTTP server. - 2
- If you use multiple NICs, specify a single interface in the
ip
option. For example, to use DHCP on a NIC that is namedeno1
, setip=eno1:dhcp
. - 3
- Specify locations of the RHCOS files that you uploaded to your HTTP server. The
initrd
parameter value is the location of theinitramfs
file, thecoreos.inst.image_url
parameter value is the location of the compressed metal RAW image, and thecoreos.inst.ignition_url
parameter value is the location of the worker Ignition config file.
注意This configuration does not enable serial console access on machines with a graphical console. To configure a different console, add one or more
console=
arguments to theAPPEND
line. For example, addconsole=tty0 console=ttyS0
to set the first PC serial port as the primary console and the graphical console as a secondary console. For more information, see How does one set up a serial terminal and/or console in Red Hat Enterprise Linux?.For iPXE:
kernel http://<HTTP_server>/rhcos-<version>-installer-kernel-<architecture> ip=dhcp rd.neednet=1 initrd=http://<HTTP_server>/rhcos-<version>-installer-initramfs.<architecture>.img coreos.inst=yes coreos.inst.install_dev=sda coreos.inst.image_url=http://<HTTP_server>/rhcos-<version>-metal.<arhcitectutre>.raw.gz coreos.inst.ignition_url=http://<HTTP_server>/worker.ign 1 2 initrd http://<HTTP_server>/rhcos-<version>-installer-initramfs.<architecture>.img 3 boot
- 1
- Specify locations of the RHCOS files that you uploaded to your HTTP server. The
kernel
parameter value is the location of thekernel
file, theinitrd
parameter value is the location of theinitramfs
file, thecoreos.inst.image_url
parameter value is the location of the compressed metal RAW image, and thecoreos.inst.ignition_url
parameter value is the location of the worker Ignition config file. - 2
- If you use multiple NICs, specify a single interface in the
ip
option. For example, to use DHCP on a NIC that is namedeno1
, setip=eno1:dhcp
. - 3
- Specify the location of the
initramfs
file that you uploaded to your HTTP server.
注意This configuration does not enable serial console access on machines with a graphical console. To configure a different console, add one or more
console=
arguments to thekernel
line. For example, addconsole=tty0 console=ttyS0
to set the first PC serial port as the primary console and the graphical console as a secondary console. For more information, see How does one set up a serial terminal and/or console in Red Hat Enterprise Linux?.
- Use the PXE or iPXE infrastructure to create the required compute machines for your cluster.
9.3.3. Approving the certificate signing requests for your machines
When you add machines to a cluster, two pending certificate signing requests (CSRs) are generated for each machine that you added. You must confirm that these CSRs are approved or, if necessary, approve them yourself. The client requests must be approved first, followed by the server requests.
Prerequisites
- You added machines to your cluster.
Procedure
Confirm that the cluster recognizes the machines:
$ oc get nodes
Example output
NAME STATUS ROLES AGE VERSION master-0 Ready master 63m v1.18.3 master-1 Ready master 63m v1.18.3 master-2 Ready master 64m v1.18.3 worker-0 NotReady worker 76s v1.18.3 worker-1 NotReady worker 70s v1.18.3
The output lists all of the machines that you created.
Review the pending CSRs and ensure that you see the client requests with the
Pending
orApproved
status for each machine that you added to the cluster:$ oc get csr
Example output
NAME AGE REQUESTOR CONDITION csr-8b2br 15m system:serviceaccount:openshift-machine-config-operator:node-bootstrapper Pending csr-8vnps 15m system:serviceaccount:openshift-machine-config-operator:node-bootstrapper Pending ...
In this example, two machines are joining the cluster. You might see more approved CSRs in the list.
If the CSRs were not approved, after all of the pending CSRs for the machines you added are in
Pending
status, approve the CSRs for your cluster machines:注意Because the CSRs rotate automatically, approve your CSRs within an hour of adding the machines to the cluster. If you do not approve them within an hour, the certificates will rotate, and more than two certificates will be present for each node. You must approve all of these certificates. Once the client CSR is approved, the Kubelet creates a secondary CSR for the serving certificate, which requires manual approval. Then, subsequent serving certificate renewal requests are automatically approved by the
machine-approver
if the Kubelet requests a new certificate with identical parameters.To approve them individually, run the following command for each valid CSR:
$ oc adm certificate approve <csr_name> 1
- 1
<csr_name>
is the name of a CSR from the list of current CSRs.
To approve all pending CSRs, run the following command:
$ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs --no-run-if-empty oc adm certificate approve
Now that your client requests are approved, you must review the server requests for each machine that you added to the cluster:
$ oc get csr
Example output
NAME AGE REQUESTOR CONDITION csr-bfd72 5m26s system:node:ip-10-0-50-126.us-east-2.compute.internal Pending csr-c57lv 5m26s system:node:ip-10-0-95-157.us-east-2.compute.internal Pending ...
If the remaining CSRs are not approved, and are in the
Pending
status, approve the CSRs for your cluster machines:To approve them individually, run the following command for each valid CSR:
$ oc adm certificate approve <csr_name> 1
- 1
<csr_name>
is the name of a CSR from the list of current CSRs.
To approve all pending CSRs, run the following command:
$ oc get csr -o go-template='{{range .items}}{{if not .status}}{{.metadata.name}}{{"\n"}}{{end}}{{end}}' | xargs oc adm certificate approve
After all client and server CSRs have been approved, the machines have the
Ready
status. Verify this by running the following command:$ oc get nodes
Example output
NAME STATUS ROLES AGE VERSION master-0 Ready master 73m v1.20.0 master-1 Ready master 73m v1.20.0 master-2 Ready master 74m v1.20.0 worker-0 Ready worker 11m v1.20.0 worker-1 Ready worker 11m v1.20.0
注意It can take a few minutes after approval of the server CSRs for the machines to transition to the
Ready
status.
Additional information
- For more information on CSRs, see Certificate Signing Requests.