new article on openshift sno

content/english/blog/deploy-openshift-single-node-in-kvm/index.md

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+---
+title: "Deploy OpenShift Single Node in KVM"
+date: 2021-06-09T00:00:00+02:00
+opensource:
+- OpenShift
+topics:
+- Containers
+resources:
+- '*.png'
+- '*.svg'
+---
+
+Starting with version 4.8, OpenShift can now officially be installed on a single virtual machine (instead of three).
+This effectively lowers the resources requirements and open up new possibilities for home labs or developer workstations.
+This article explores how to deploy OpenShift Single Node (SNO) using KVM on your Fedora workstation.
+
+<!--more-->
+
+## Pre-requisites
+
+On your Fedora workstation, make sure you installed the required packages [as explained in the Fedora documentation](https://docs.fedoraproject.org/en-US/quick-docs/getting-started-with-virtualization/).
+
+Configure [NetworkManager to use dnsmasq]({{<relref "/blog/consistent-dns-name-resolution-for-virtual-machines-and-containers/index.md" >}}) for DNS resolution.
+
+Choose a base domain name and a cluster name.
+The base domain does not need to be public or registered somewhere.
+It just has to be unique.
+In the rest of this article, I chose **ocp.itix**.
+
+The cluster name can be anything you want.
+I chose **itix-dev**.
+
+Combined together, those two pieces of information defines the DNS name of your cluster: **\<cluster_name>.\<base_domain>**.
+The kubernetes API will be available at `api.<cluster_name>.<base_domain>`.
+The OpenShift routes will be available at `*.apps.<cluster_name>.<base_domain>`.
+
+Note: Do **not** choose a **.local** base domain as it is reserved for multicast DNS.
+
+Last but not least, you will need a user account on **cloud.redhat.com**.
+You can get one for free by registering as a developer [here](https://developers.redhat.com/register/).
+
+## Create the libvirt network
+
+Create the libvirt network definition.
+
+{{< highlightFile "/tmp/ocp-net.xml" "xml" "" >}}
+<network xmlns:dnsmasq="http://libvirt.org/schemas/network/dnsmasq/1.0">
+  <name>ocp-dev</name>
+  <forward mode='nat'>
+    <nat>
+      <port start='1024' end='65535'/>
+    </nat>
+  </forward>
+  <bridge name='virbr1' stp='on' delay='0'/>
+  <ip address='192.168.123.1' netmask='255.255.255.0'>
+    <dhcp>
+      <range start='192.168.123.2' end='192.168.123.254'/>
+      <host mac="02:01:00:00:00:66" name="node.itix-dev.ocp.itix" ip="192.168.123.5"/>
+    </dhcp>
+  </ip>
+  <dns>
+    <host ip="192.168.123.5"><hostname>api.itix-dev.ocp.itix</hostname></host>
+  </dns>
+  <dnsmasq:options>
+    <!-- fix for the 5s timeout on DNS -->
+    <!-- see https://www.math.tamu.edu/~comech/tools/linux-slow-dns-lookup/ -->
+    <dnsmasq:option value="auth-server=itix-dev.ocp.itix,"/><!-- yes, there is a trailing coma -->
+    <dnsmasq:option value="auth-zone=itix-dev.ocp.itix"/>
+    <!-- Wildcard route -->
+    <dnsmasq:option value="host-record=lb.itix-dev.ocp.itix,192.168.123.5"/>
+    <dnsmasq:option value="cname=*.apps.itix-dev.ocp.itix,lb.itix-dev.ocp.itix"/>
+  </dnsmasq:options>
+</network>
+{{< /highlightFile >}}
+
+This file defines a libvirt network named **ocp-dev** and add the required DNS records for a standard installation of OpenShift.
+Make sure to replace **itix-dev.ocp.itix** by your cluster name and base domain.
+
+There is a DHCP reservation for the MAC address of the OpenShift virtual machine.
+This MAC address is used below during the installation.
+
+Create the libvirt network, start it and flag it as autostart.
+
+```sh
+sudo virsh net-define /tmp/ocp-dev-net.xml
+sudo virsh net-start ocp-dev
+sudo virsh net-autostart ocp-dev
+```
+
+## Create the cluster on cloud.redhat.com
+
+To install OpenShift Single Node, we will use a new technology called "Assisted Installer".
+Once you declared your cluster on cloud.redhat.com, an ISO image is generated.
+This ISO image is used to boot the machine that will host your OpenShift.
+The ISO image contains a program that will register the machine on cloud.redhat.com and once you validate the installation, the machine pulls its installation instructions from cloud.redhat.com and start installing OpenShift.
+
+Create a cluster with [the Assisted Installer](https://cloud.redhat.com/openshift/assisted-installer/clusters/~new).
+
+* Click **Clusters** > **Create cluster**
+* Choose **Datacenter** and click **Create cluster** (just under **Assisted installer**)
+
+Configure the cluster.
+
+* Fill-in the **Cluster Name**, **Base Domain**
+* Check **I want to install single node OpenShift (SNO)**
+* Click **Next**
+
+{{< attachedFigure src="assisted-installer-1.png" title="Assisted Installer: configure the cluster." >}}
+
+Generate the ISO image.
+
+* Click **Generate Discovery ISO**
+* Copy/paste your SSH public key. You will use it to complete the installation.
+* Once the ISO has been generated, copy the **Discovery ISO URL**
+
+Download the ISO image under **/var/lib/libvirt/images**.
+
+```sh
+sudo curl -Lo /var/lib/libvirt/images/discovery_image.iso 'https://s3.us-east-1.amazonaws.com/assisted-installer/discovery-image-....'
+```
+
+Boot a Virtual Machine on the downloaded ISO image.
+Make sure to adjust the CPUs, memory and disk size but leave the MAC address as-is since it must match the DHCP host record declared in the libvirt network.
+
+```sh
+sudo virt-install -n ocp-dev --memory 65536 --vcpus=12 --os-variant=fedora-coreos-stable --accelerate -v --cpu host-passthrough,cache.mode=passthrough --disk path=/var/lib/libvirt/images/ocp-dev.qcow2,size=120 --network network=ocp-dev,mac=02:01:00:00:00:66 --cdrom /var/lib/libvirt/images/discovery_image.iso
+```
+
+On cloud.redhat.com, wait for the node to appear in the list.
+
+* Click **Next**.
+
+{{< attachedFigure src="assisted-installer-2.png" title="Assisted Installer: wait for the node to appear in the list." >}}
+
+* Select your Network Subnet in the dropdown list.
+* Click **Next**.
+* Click **Install Cluster**.
+
+You can follow the installation process from cloud.redhat.com.
+Once the installation is complete, download the **kubeadmin** password and make sure you can access the OpenShift Console.
+
+{{< attachedFigure src="assisted-installer-5.png" title="Assisted Installer: the installation is complete." >}}
+
+Also, make sure you can login with SSH to your OpenShift node.
+If you configured NetworkManager and dnsmasq [as explained here]({{<relref "/blog/consistent-dns-name-resolution-for-virtual-machines-and-containers/index.md" >}}), you should be able to reach your OpenShift node by its DNS name.
+Otherwise, use the IP address.
+
+```sh
+ssh core@node.itix-dev.ocp.itix
+```
+
+## Configure storage
+
+By default, OpenShift does not provision any storage for your containers.
+To be able to use persistent storage, we need to create Persistent Volumes and a Storage Class.
+
+Create some storage under **/srv/openshift** for your containers.
+
+```sh
+ssh core@node.itix-dev.ocp.itix "sudo /bin/bash -c 'mkdir -p /srv/openshift/pv-{0..99} ; chmod -R 777 /srv/openshift ; chcon -R -t svirt_sandbox_file_t /srv/openshift'"
+```
+
+Create the matching Persistent Volumes.
+
+```sh
+for i in {0..99}; do
+  oc create -f - <<EOF
+apiVersion: v1
+kind: PersistentVolume
+metadata:
+  name: pv-$i
+  labels:
+    type: local
+spec:
+  storageClassName: manual
+  capacity:
+    storage: 10Gi
+  accessModes:
+  - ReadWriteOnce
+  - ReadWriteMany
+  persistentVolumeReclaimPolicy: Recycle
+  hostPath:
+    path: "/srv/openshift/pv-$i"
+EOF
+done
+```
+
+Create the Storage Class.
+
+```sh
+oc create -f - <<EOF
+kind: StorageClass
+apiVersion: storage.k8s.io/v1
+metadata:
+  name: manual
+  annotations:
+    storageclass.kubernetes.io/is-default-class: 'true'
+provisioner: kubernetes.io/no-provisioner
+reclaimPolicy: Delete
+volumeBindingMode: WaitForFirstConsumer
+EOF
+```
+
+## Configure the internal registry
+
+Just after installation, the OpenShift internal registry is waiting for storage to become available.
+Now that we provisioned some storage, let's configure the registry accordingly.
+
+Create a Persistent Volume Claim for the registry.
+
+```sh
+oc create -f - <<EOF
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: registry-storage
+  namespace: openshift-image-registry
+spec:
+  accessModes:
+  - ReadWriteMany
+  resources:
+    requests:
+      storage: 10Gi
+EOF
+```
+
+Change the configuration of the Registry Operator to use the new PVC.
+
+```sh
+oc patch configs.imageregistry.operator.openshift.io cluster --type=json --patch-file=/dev/fd/0 <<EOF
+[{"op": "remove", "path": "/spec/storage" },{"op": "add", "path": "/spec/storage", "value": {"pvc":{"claim": "registry-storage"}}}]
+EOF
+oc patch configs.imageregistry.operator.openshift.io cluster --type merge --patch-file=/dev/fd/0 <<EOF
+{"spec":{"managementState": "Managed"}}
+EOF
+```
+
+Congratulation! You now have an OpenShift Single Node that is fully functional.
+