Stumbling into Azure Part II: Setting up a private ARO cluster

OpenShift

- Toni Schmidbauer Toni Schmidbauer ( Lastmod: 2024-05-08 ) - 2 min read

In Part I of our blog post we covered setting up required resources in Azure. Now we are finally going to set up a private cluster. Private

As review from Part I here is our planned setup, this time including the ARO cluster.

Azure Setup

The diagram below depicts our planned setup:

/azure/images/azure_network_setup_with_aro.png

On the right hand side can see the resources required for our lab:

  • a virtual network (vnet 192.168.128.0/19). This vnet will be split into 3 separate subnets
  • a master subnet (192.168.129.0/24) holding the ARO control plane nodes
  • a node subnet (192.168.130.0/24) holding ARO worker nodes
  • and finally a subnet call GatewaySubnet where we are going to deploy our Azure VPN gateway (called a vnet-gateway)

    The subnet where the Azure VPN gateway is located needs to have the name GatewaySubnet. Otherwise creating the Azure VPN gateway will fail.

  • we also need a publicIP resource that we are going to connect to our vnet-gateway (the VPN gateway)
  • and finally a local-gateway resource that tells the vnet-gateway which networks are reachable on the left, in our case the Hetzner server.

Creating the private Azure Red Hat OpenShift cluster

  1. Register required resource providers

    az provider register -n Microsoft.RedHatOpenShift --wait
az provider register -n Microsoft.Compute --wait
az provider register -n Microsoft.Storage --wait
az provider register -n Microsoft.Authorization --wait

  1. First we are going to set some environment variable. Those variables are used in the upcoming commands:

    export RESOURCEGROUP=aro-rg
export CLUSTER="aro1"
export GATWAY_SUBNET="192.168.128.0/24"
export MASTER_SUBNET="192.168.129.0/24"
export WORKER_SUBNET="192.168.130.0/24"
export HETZNER_VM_NETWORKS="10.0.0.0/24 192.168.122.0/24 172.16.100.0/24"

  2. Disable subnet private endpoint policies

    az network vnet subnet update \
--name master-subnet \
--resource-group $RESOURCEGROUP \
--vnet-name aro-vnet \
--disable-private-link-service-network-policies true

  3. Create a private DNS zone for our cluster

    az network private-dns zone create -n private2.tntinfra.net -g aro-rg

  4. Create the cluster

    az aro create \
--resource-group $RESOURCEGROUP \
--name $CLUSTER \
--vnet aro-vnet \
--master-subnet master-subnet \
--worker-subnet worker-subnet \
--apiserver-visibility Private \
--ingress-visibility Private \
--domain private.tntinfra.net
# --pull-secret @pull-secret.txt # [OPTIONAL]

  5. After successful cluster creating add DNS entry for the API and Ingress

    Query the Azure API for the API server IP and the ingress IP addresses:

    az aro show -n aro1 -g aro-rg --query '{api:apiserverProfile.ip, ingress:ingressProfiles[0].ip}'

    Example output

    Api            Ingress
-------------  ---------------
192.168.129.4  192.168.130.254

    Add entries to Azure private DNS

    az network private-dns record-set a add-record -g aro-rg -z private.tntinfra.net -a "192.168.129.4" -n api
az network private-dns record-set a add-record -g aro-rg -z private.tntinfra.net -a "192.168.130.254" -n "*.apps"

    List entries to verify configuration

    az network private-dns record-set a list -g aro-rg -z private.tntinfra.net

    Output:

    Name    ResourceGroup    Ttl    Type    AutoRegistered    Metadata
------  ---------------  -----  ------  ----------------  ----------
api     aro-rg           3600   A       False
*.apps  aro-rg           3600   A       False

  6. List cluster credentials after successful setup

    az aro list-credentials \
--name $CLUSTER \
--resource-group $RESOURCEGROUP

  7. Get the console URL

    az aro show \
--name $CLUSTER \
--resource-group $RESOURCEGROUP \
--query "consoleProfile.url" -o tsv

DNS, curl

this works, dunno why?

dig @192.168.129.7 console-openshift-console.apps.xm7rdz4r.westeurope.aroapp.io

use curl to access the internal API and see if it works:

curl -kv https://192.168.129.4:6443

See Also:

  • Introducing AdminNetworkPolicies –

    Classic Kubernetes/OpenShift offer a feature called NetworkPolicy that allows users to control the traffic to and from their assigned Namespace. NetworkPolicies are designed to give project owners or tenants the ability to protect their own namespace. Sometimes, however, I worked with customers where the cluster administrators or a dedicated (network) team need to enforce these policies. Since the NetworkPolicy API is namespace-scoped, it is not possible to enforce policies across namespaces. The only solution was to create custom (project) admin and edit roles, and remove the ability of creating, modifying or deleting NetworkPolicy objects. Technically, this is possible and easily done. But shifts the whole network security to cluster administrators. Luckily, this is where AdminNetworkPolicy (ANP) and BaselineAdminNetworkPolicy (BANP) comes into play.

  • Using Kustomize to post render a Helm Chart –

    Lately I came across several issues where a given Helm Chart must be modified after it has been rendered by Argo CD. Argo CD does a helm template to render a Chart. Sometimes, especially when you work with Subcharts or when a specific setting is not yet supported by the Chart, you need to modify it later …​ you need to post-render the Chart. In this very short article, I would like to demonstrate this on a real-live example I had to do. I would like to inject annotations to a Route objects, so that the certificate can be injected. This is done by the cert-utils operator. For the post-rendering the Argo CD repo pod will be extended with a sidecar container, that is watching for the repos and patches them if required.

  • Managing Certificates using GitOps approach –

    The article SSL Certificate Management for OpenShift on AWS explains how to use the Cert-Manager Operator to request and install a new SSL Certificate. This time, I would like to leverage the GitOps approach using the Helm Chart cert-manager I have prepared to deploy the Operator and order new Certificates. I will use an ACME Letsencrypt issuer with a DNS challenge. My domain is hosted at AWS Route 53. However, any other integration can be easily used.

  • Update Cluster Version using GitOps approach –

    During a GitOps journey at one point, the question arises, how to update a cluster? Nowadays it is very easy to update a cluster using CLI or WebUI, so why bother with GitOps in that case? The reason is simple: Using GitOps you can be sure that all clusters are updated to the correct, required version and the version of each cluster is also managed in Git. All you need is the channel you want to use and the desired cluster version. Optionally, you can define the exact image SHA. This might be required when you are operating in a restricted environment.

  • Multiple Sources for Applications in Argo CD –

    Argo CD or OpenShift GitOps uses Applications or ApplicationSets to define the relationship between a source (Git) and a cluster. Typically, this is a 1:1 link, which means one Application is using one source to compare the cluster status. This can be a limitation. For example, if you are working with Helm Charts and a Helm repository, you do not want to re-build (or re-release) the whole chart just because you made a small change in the values file that is packaged into the repository. You want to separate the configuration of the chart with the Helm package. The most common scenarios for multiple sources are (see: Argo CD documentation): Your organization wants to use an external/public Helm chart You want to override the Helm values with your own local values You don’t want to clone the Helm chart locally as well because that would lead to duplication and you would need to monitor it manually for upstream changes. This small article describes three different ways with a working example and tries to cover the advantages and disadvantages of each of them. They might be opinionated but some of them proved to be easier to use and manage.

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