Cloud Experts Documentation

Adding a Public Ingress endpoint to a ROSA PrivateLink Cluster

This content is authored by Red Hat experts, but has not yet been tested on every supported configuration.

This is an example guide for creating a public ingress endpoint for a ROSA Private-Link cluster. Be aware of the security implications of creating a public subnet in your ROSA VPC this way.

architecture diagram showing privatelink with public ingress

Refer to the blog “How to add public Ingress to a PrivateLink ROSA cluster” , to expose applications to the internet by deploying in a PrivateLink Red Hat OpenShift Service on AWS (ROSA) cluster within a truly private Virtual Private Cloud (VPC) that doesn’t have an internet gateway attached to it. Additionally, the blog details about creating CloudFront distribution for content delivery and WAF to protect web applications by filtering and monitoring HTTP traffic between a web application and the internet. Also,AWS network firewall will be used for fine-grained control over network traffic.


Getting Started

Set some environment variables

  1. Set the following environment variables, changing them to suit your cluster.

    export ROSA_CLUSTER_NAME=private-link
    # this should be a free CIDR inside your VPC
    export PUBLIC_CIDR=
    export AWS_PAGER=""
    export SCRATCH_DIR=/tmp/scratch
    mkdir -p $SCRATCH_DIR

Create a public subnet

If you followed the above instructions to create the ROSA Private-Link cluster, you should already have a public subnet in your VPC and can skip to tagging the subnet.

  1. Get a Private Subnet ID from the cluster.

    PRIVATE_SUBNET_ID=$(rosa describe cluster -c $ROSA_CLUSTER_NAME -o json \
       | jq -r '.aws.subnet_ids[0]')
  2. Get the VPC ID from the subnet ID.

     VPC_ID=$(aws ec2 describe-subnets --subnet-ids $PRIVATE_SUBNET_ID \
       --query 'Subnets[0].VpcId' --output text)
     echo $VPC_ID
  3. Get the Cluster Tag from the subnet

    TAG=$(aws ec2 describe-subnets --subnet-ids $PRIVATE_SUBNET_ID \
       --query 'Subnets[0].Tags[?Value == `shared`]' | jq -r '.[0].Key')
    echo $TAG
  4. Create a public subnet

    PUBLIC_SUBNET=`aws ec2 create-subnet --vpc-id $VPC_ID --cidr-block $PUBLIC_CIDR \
      --query 'Subnet.SubnetId' --output text`
  5. Tag the public subnet for the cluster

    aws ec2 create-tags --resources $PUBLIC_SUBNET \
       --tags Key=Name,Value=$ROSA_CLUSTER_NAME-public \

Create a Custom Domain

  1. Create TLS Key Pair for custom domain using certbot:

    Skip this if you already have a key pair.

    certbot certonly --manual \
      --preferred-challenges=dns \
      --email $EMAIL \
      --server \
      --agree-tos \
      --config-dir "$SCRATCH_DIR/config" \
      --work-dir "$SCRATCH_DIR/work" \
      --logs-dir "$SCRATCH_DIR/logs" \
      -d "*.$DOMAIN"
  2. Create TLS secret for custom domain:

    Note use your own keypair paths if not using certbot.

    oc new-project my-custom-route
    oc create secret tls acme-tls --cert=$CERTS/fullchain.pem --key=$CERTS/privkey.pem
  3. Create Custom Domain resource:

    cat << EOF | oc apply -f -
    kind: CustomDomain
      name: acme
      domain: $DOMAIN
        name: acme-tls
        namespace: my-custom-route
  4. Wait for the domain to be ready:

    watch oc get customdomains
  5. Once its ready grab the CLB name:

    CLB_NAME=$(oc get svc -n openshift-ingress -o jsonpath='{range .items[?(@.metadata.labels.ingresscontroller\.operator\.openshift\.io\/owning-ingresscontroller=="'$CDO_NAME'")]}{.status.loadBalancer.ingress[].hostname}{"\n"}{end}')
    echo $CLB_NAME
  6. Create a CNAME in your DNS provider for *.<$DOMAIN> that points at the CLB NAME from the above command.

Deploy a public application

  1. Create a new project

    oc new-project my-public-app
  2. Create a new application

    oc new-app
  3. Create a route for the application

    oc create route edge --service=hello-openshift hello-openshift-tls \
      --hostname hello.$DOMAIN
  4. Check that you can access the application:

    curl https://hello.$DOMAIN
  5. You should see the output

    Hello OpenShift!

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