[vsphere_ci] Add PTR records for platform=none

docs/vsphere_ci/platform-none/README.md

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+# Adding PTR records for platform=none CI clusters in vSphere
+
+WMCO' CSRs approver requires reverse DNS lookup for each Windows instance that 
+joins the cluster as a Windows worker. For CI clusters with platform-agnostic
+infrastructure (platform=none) a fixed lease pool is configured to ensure latter 
+requirement is met.
+
+The `create-ptr-records.sh` script enables the reverse DNS lookup by creating
+PTR records for each IP address available in the selected subnets.
+
+vSphere CI (`vmc-ci.devcluster.openshift.com`) uses AWS Route53 for DNS
+resolution and the following ci-segments are reserved for platform=none clusters
+- ci-segment-56
+- ci-segment-47
+- ci-segment-58
+- ci-segment-59 
+
+each segment sits on a `/27` subnet (`192.168.x.1/27`) with DHCP range from
+`192.168.x.10` to `192.168.x.30`, where `x` accounts for the third octet and 
+matches the number of the ci-segment, from 56 to 59 inclusive. DNS is provided
+by the VPC with server IP `10.0.0.2`.
+
+Before running the `create-ptr-records.sh` script, ensure AWS CLI is properly
+configured with AWS credentials and region for `openshift-vmware-cloud-ci`
+account, for example:
+```shell
+# configures AWS CLI
+export AWS_PROFILE="openshift-vmware-cloud-ci"
+export AWS_REGION="us-west-2"
+
+# run script
+./create-ptr-records.sh
+```
+where `openshift-vmware-cloud-ci` is the name of profile that contains the
+credentials, and `us-west-2` is the region where the resources were provisioned.

docs/vsphere_ci/platform-none/create-ptr-records.sh

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+#!/bin/bash
+
+# create-ptr-records.sh - Create PTR records in AWS Route53 for CI' platform=none clusters.
+#
+# USAGE
+#    create-ptr-records.sh
+#
+# PREREQUISITES
+#    aws      to fetch VPC information and create hosted zone with record sets
+
+# name of the VPC cloud formation stack
+VSPHERE_VPC_STACK_NAME="vsphere-vpc"
+
+# ci-segments for platform=none in vSphere
+CI_SEGMENTS=(56 57 58 59)
+
+# start and end IP addresses of the subnet
+SUBNET_START=10
+SUBNET_END=30
+
+# createJSONRecordSets creates the JSON batch file with the PTR record sets
+# for the given IP range.
+function createJSONRecordSets () {
+    batch_file=$1; third_octet=$2
+    # init change_batch.json file content
+    cat <<EOF > ${batch_file}
+{
+  "Comment": "PTR records for ci-segment-${third_octet}",
+  "Changes": [
+EOF
+    # loop ip range
+    for ip in $(seq $SUBNET_START $SUBNET_END); do
+        # append record set
+        cat <<EOF >> ${batch_file}
+    {
+      "Action": "CREATE",
+      "ResourceRecordSet": {
+        "Name": "${ip}.${third_octet}.168.192.in-addr.arpa",
+        "Type": "PTR",
+        "TTL": 172800,
+        "ResourceRecords": [
+          {
+            "Value": "192.168.${third_octet}.${ip}"
+          }
+        ]
+      }
+    }$([[ $ip = $SUBNET_END ]] && echo "" || echo ",")
+EOF
+    done
+    cat <<EOF >> ${batch_file}
+  ]
+}
+EOF
+}
+
+# find the VPC ID
+VPC_ID=$(aws cloudformation describe-stacks \
+    --region $AWS_REGION \
+    --stack-name $VSPHERE_VPC_STACK_NAME \
+    | jq -r '.Stacks[0].Outputs[] | select(.OutputKey | contains("VpcId")).OutputValue') || {
+    echo "Error getting vSphere VPC ID"
+    exit 1
+}
+
+# create temp file for batch data
+batch_file=$(mktemp)
+
+# loop ci-segments
+for third_octet in "${CI_SEGMENTS[@]}"; do
+    echo "Processing ci-segment-$third_octet"
+    echo "Creating private hosted zone associate to VPC $AWS_REGION/$VPC_ID"
+    hosted_zone_id=$(aws route53 create-hosted-zone \
+        --name "${third_octet}".168.192.in-addr.arpa \
+        --hosted-zone-config PrivateZone=true,Comment="Hosted zone for VMC ci-segment-${third_octet}" \
+        --caller-reference "$(uuidgen)" \
+        --vpc VPCRegion="$AWS_REGION",VPCId="$VPC_ID" | jq -r '.HostedZone.Id') || {
+            echo "Error creating hosted zone for ci-segment-${third_octet}"
+            exit 1
+        }
+    echo "Created hosted zone $hosted_zone_id for ci-segment-${third_octet}"
+
+    echo "Creating PTR record sets batch file for ci-segment-${third_octet}"
+    createJSONRecordSets "${batch_file}" "${third_octet}"
+
+    echo "Adding PTR record sets to hosted zone ${hosted_zone_id}"
+    aws route53 change-resource-record-sets \
+      --hosted-zone-id "${hosted_zone_id}" \
+      --change-batch file://"${batch_file}" || {
+        echo "Error creating PTR record sets for hosted zone ${hosted_zone_id} from batch file ${batch_file}"
+        exit 1
+      }
+done
+
+# cleanup
+rm -f "${batch_file}"
+
+# success
+exit 0