miror09 / ocp4-lab

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OpenShift 4.2 UPI bare-metal (using PXE boot)

This is a reference documentation for POCs of OpenShift 4.2 UPI bare-metal deployment using PXE Boot.

The initial deployment is as per the following diagram

OCP Bootstrap Deployment

NOTE: Even when the diagram shows two different load balancers, the access for the operations and administration tasks as well as the applications traffic are documented to go over the same load balancer. For a production grade deployment, the control and operation ports (K8s API, Machine Server, etc.) should not be exposed outside the organization.


  1. Clone this repo to the Bastion Node
  2. Edit the install-config.yaml to match your environment
  3. Execute poc.sh script:
./poc.sh clean

./poc.sh ignition

./poc.sh custom

./poc.sh prep_ign
  1. Power up the Bootstrap Node and PXE install the RHCOS
  2. Power up the Master Nodes and PXE install the RHCOS
# Monitor bootstrap progress:
./poc.sh bootstrap
  1. Once bootstrap complete, shutdown Bootstrap Node
  2. Power up the Worker Nodes and PXE install
# Monitor OCP install
./poc.sh install
  1. Monitor CSR requests from the Worker Nodes and accept the certificates

NOTE: There are two CSR's per Node that need to be accepted.

$ export KUBECONFIG=./ocp4poc/auth/kubeconfig

$ ./oc get csr

$ ./oc adm certificate approve <crt-name>

Reference Environment

  • Base Domain: example.com
  • Cluster Name: ocp4poc

NOTE: For easy customization, clone this repo to your Bastion Node.

Modify the following environment variables of ./poc.sh script to match your environment.



NOTE: Next instructions assume this has been customized.


DNS Configuration

  • Example of forward DNS records included in the utils folder
  • Example of reverse records included in the utils folder
  • DNS must have entries for:
    • DNS forward records for all Nodes
    • DNS reverse records for all the Nodes
    • DNS entries for special records used by OCP: etcd, etcd srv, api, api-int, and *.apps wildcard subdomain

Reference official documentation for details on special entries required in DNS.

NOTE: If there is NO way to reach out to the external NTP and DNS servers from the masters and workers node then you can set proxy DNS . DNS/NTP query in this will flow like this .

  • master node > bastion node > external DNS/NTP server
  • worker node > bastion node > external DNS/NTP server

In this case no need to use bastion as recursive DNS, set port=0 in /etc/dnsmasq.conf file.

NOTE: While setting up the external DNS server make sure the A records priorities for master and etcd are set properly . We want to have higher priority for master A records as compared to etcd A record . Otherwise what will happen is when we try to install master nodes ,during the reverse lookup step it might get the etcd FQDN instead of master FQDN!!

NOTE: If using Microsoft external DNS server you can use CNAME for etcd FQDN's

Load Balancer Configuration

  • Setup load balancerconfiguration in pass-through for Kubernetes API (tcp/6443), Machine Server Config (tcp/22623), OpenShift Routers HTTP and HTTPS (tcp/80, tcp/443)

Reference Load Balancer configurations available in the utils folder (use one of the two):

  • Load balancer using HAProxy at system level (installed from RPM)
  • Load balancer using HAProxy as System Container managed by systemd

NOTE: If seeing port bind errors starting the load balancer check SELinux settings:

# List the permited ports
semanage port -l | grep http_port_t

# If need to add ports
semanage port -a -t http_port_t -p tcp 6443
semanage port -a -t http_port_t -p tcp 22623
semanage port -m -t http_port_t -p tcp 8000

Preparing the Bastion Node

  • Install PXE Boot pre-requisites

    yum -y install https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
    yum -y install tftp-server dnsmasq syslinux-tftpboot tree python36 jq oniguruma
    subscription-manager repos --enable rhel-7-server-extras-rpms
    yum -y install podman skopeo
  • (optional) Setup HAProxy as load balancer

    • Update ./utils/haproxy.cfg to match your environment
    mkdir -pv /opt/haproxy
    cp ./utils/haproxy.cfg /opt/haproxy
    cp ./utils/poc-lb.service /etc/systemd/system/poc-lb.service
    podman pull haproxy
    systemctl daemon-reload
    systemctl start poc-lb
    systemctl status poc-lb
    systemctl enable poc-lb

    Note: To accept asymmetrically routed packets set rp_filter = 2 (Credits: Thanks to Jay Cromer)

    echo "net.ipv4.conf.default.rp_filter = 2" >> /etc/sysctl.conf 
    echo "net.ipv4.conf.all.rp_filter = 2" >> /etc/sysctl.conf 
    echo 2 > /proc/sys/net/ipv4/conf/default/rp_filter
    echo 2 > /proc/sys/net/ipv4/conf/all/rp_filter
  • Setup web server for Ignition and PXE files

    mkdir -pv /opt/nginx/html/metal
    cp ./utils/poc-pxe-http.service /etc/systemd/system/poc-pxe-http.service
    podman pull nginx
    systemctl daemon-reload
    systemctl start poc-pxe-http
    systemctl status poc-pxe-http
    systemctl enable poc-pxe-http

Setting up DNSmasq for PXE Boot

  1. (if already running Bind server in Bastion) Disable DNS in DNSmasq by setting port=0
    vi /etc/dnsmasq.conf
  2. Configure DHCP and DHCP PXE Options following the reference dnsmasq-pxe.conf
    cp ./utils/dnsmasq-pxe.conf /etc/dnsmasq.d/dnsmasq-pxe.conf

NOTE: Update /etc/dnsmasq.d/dnsmasq-pxe.conf to match environment

Setup PXE Boot Configurations

  1. Create PXE Boot menu to be used by the environment /var/lib/tftpboot/pxelinux.cfg/default
mkdir -pv /var/lib/tftpboot/pxelinux.cfg/

copy ./utils/pxelinux.cfg-default-bios /var/lib/tftpboot/pxelinux.cfg/default

NOTE: Update /var/lib/tftpboot/pxelinux.cfg/default to match environment.

  1. Download RHCOS images.
  • Running ./poc.sh get_images download all the images to ./images on your current directory. It should be similar to this list (versions may be different):

    ├── openshift-client-linux-4.2.0-0.nightly-2019-10-01-210901.tar.gz
    ├── openshift-install-linux-4.2.0-0.nightly-2019-10-01-210901.tar.gz
    ├── rhcos-42.80.20190828.2-installer-initramfs.img
    ├── rhcos-42.80.20190828.2-installer-kernel
    └── rhcos-42.80.20190828.2-metal-bios.raw.gz
  1. Open the openshift-client-linux-<release>.tar.gz and the openshift-install-linux-<release>.tar.gz into your current directory. This will provide the openshift-installer, oc and kubectl binaries.

  2. Copy RHCOS PXE images and RHCOS images into the corresponding folders

./poc.sh prep_images
  1. Uncompress installer and client binaries into current directory
./poc.sh prep_installer

Ports to open if Bastion node running all the ancillary services

firewall-cmd --zone=public   --change-interface=eth0
firewall-cmd --zone=internal --change-interface=eth1

firewall-cmd --get-active-zones

firewall-cmd --zone=public   --permanent --add-port=6443/tcp 
firewall-cmd --zone=public   --permanent --add-port=22623/tcp 
firewall-cmd --zone=public   --permanent --add-service=http
firewall-cmd --zone=public   --permanent --add-service=https
firewall-cmd --zone=public   --permanent --add-service=dns

firewall-cmd --zone=internal --permanent --add-port=6443/tcp
firewall-cmd --zone=internal --permanent --add-port=22623/tcp
firewall-cmd --zone=internal --permanent --add-service=http
firewall-cmd --zone=internal --permanent --add-service=https
firewall-cmd --zone=internal --permanent --add-port=69/udp
firewall-cmd --zone=internal --permanent --add-port=8000/tcp
firewall-cmd --zone=internal --permanent --add-service=dns
firewall-cmd --zone=internal --permanent --add-service=dhcp

firewall-cmd --reload

firewall-cmd --zone=internal  --list-services
firewall-cmd --zone=internal  --list-ports


  • Create or edit install-config.yaml to include the pull secret obtained from https://try.openshift.com

  • Add the SSH Key to be used to access the Bootstrap Node to the install-config.yaml

  • Generate the Ignition files:

    ./poc.sh ignition

  • Apply custom patch for NetworkManager:

    ./poc.sh custom

  • Copy Ignition files into web server path

    ./poc.sh prep_ign

  • Boot the Bootstrap Node and at the PXE MENU select the BOOTSTRAP option and press Enter

    • This will start the process of installing RHCOS in the Bootstrap Node

      Bootstrap Menu

  • Wait until the bootstrap Node is up and showing the login prompt

(missing image here)

  • Monitor bootstrap progress using the script or the equivalent openshift-install wait-for ... command

    ./poc.sh bootstrap

  • Start the Master Nodes and select the MASTER option from the PXE menu

    Bootstrap Menu

  • The boot process of the Masters will start the RHCOS installation and use the Ignition configuration during the first install.

    • After RHCOS is installed in the Node, it will be up for a few minutes showing the login prompt and eventually will reboot. This is a normal part of the automatic upgrade process of RHCOS.
      • The Master node receives the actual configuration as a rendered Machine Config from the Bootstrap Nodes.
      • During the process, the Cluster Version Operator instruct the Master Nodes to start deploying the components corresponding to the Master Node.
      • One of the actions is the upgrade of RHCOS so the Node will download latest RHCOS version and will apply it.
      • After upgrading the OS, the Nodes reboot into the latest version of RHCOS
      • During the process, the Cluster Version Operator instruct the Master Nodes to start deploying the components corresponding to the Master Node.
  • Once the Bootstrap Node reports the bootstrap process as completed and indicates it is safe to shutdown the Bootstrap Node, proceed to shutdown the Node.

    • At this point the etcd have achieved quorum and the Master Nodes are fully operational

(missing image here)

  • Proceed to monitor the Installation process using the script or the equivalent openshift-install wait-for ... command

    ./poc install

  • Proceed to boot the Worker Nodes and select the WORKER option fromt he PXE menu

    Bootstrap Menu

  • After RHCOS is installed in the Worker node, it will go over a similar process as with the Master Nodes but this time, there will be a Certificate Signing Request (CSR) that need to be accepted before it proceeds.

    • The script provides ./poc approve to automattically approve any pending certificate. NOTE: In a production environment, the certificates should be approved ONLY after confirming the CSR is from a valid and authorized Worker Node.

(missing image here)

  • A successful installation will show all the cluster operators available. The image-registry will not become active until a cluster administrator configure storage for the registry.
# export KUBECONFIG=`pwd`/ocp4poc/auth/kubeconfig

# oc get co
NAME                                       VERSION   AVAILABLE   PROGRESSING   DEGRADED   SINCE
authentication                             4.2.0     True        False         False      9m43s
cloud-credential                           4.2.0     True        False         False      24m
cluster-autoscaler                         4.2.0     True        False         False      16m
console                                    4.2.0     True        False         False      10m
dns                                        4.2.0     True        False         False      23m
image-registry                             4.2.0     True        False         False      4m47s
ingress                                    4.2.0     True        False         False      16m
insights                                   4.2.0     True        False         False      24m
kube-apiserver                             4.2.0     True        False         False      21m
kube-controller-manager                    4.2.0     True        False         False      21m
kube-scheduler                             4.2.0     True        False         False      20m
machine-api                                4.2.0     True        False         False      24m
machine-config                             4.2.0     True        False         False      22m
marketplace                                4.2.0     True        False         False      17m
monitoring                                 4.2.0     True        False         False      12m
network                                    4.2.0     True        False         False      21m
node-tuning                                4.2.0     True        False         False      19m
openshift-apiserver                        4.2.0     True        False         False      20m
openshift-controller-manager               4.2.0     True        False         False      21m
openshift-samples                          4.2.0     True        False         False      9m34s
operator-lifecycle-manager                 4.2.0     True        False         False      22m
operator-lifecycle-manager-catalog         4.2.0     True        False         False      22m
operator-lifecycle-manager-packageserver   4.2.0     True        False         False      21m
service-ca                                 4.2.0     True        False         False      24m
service-catalog-apiserver                  4.2.0     True        False         False      20m
service-catalog-controller-manager         4.2.0     True        False         False      19m
storage                                    4.2.0     True        False         False      18m
  • Adding ephemeral storaste to the image registry can be done with the following command:
oc patch configs.imageregistry.operator.openshift.io cluster --type merge --patch '{"spec":{"storage":{"emptyDir":{}}}}'

Assigning persistent storage for image-registry

  • Set the PVC name for the image registry

    oc patch configs.imageregistry.operator.openshift.io cluster --type merge --patch '{"spec":{"storage":{"pvc":{"claim":"{changeme}"}}}}'
  • For dynamic PVC creation by the operator edit the configuration and delete the name of the claim

    oc edit configs.imageregistry.operator.openshift.io 
    # Remove the 'changeme' (including the '') and leave 'claim:' only.
  • Create PV for the image registry.

    Example: pv-image-registry.yaml

    apiVersion: v1
    kind: PersistentVolume
    name: pv-image-registry 
        storage: 100Gi 
    - ReadWriteMany 
        path: /path/to/nfs/image-registry  
    persistentVolumeReclaimPolicy: Retain 


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