Q: Your engineering org wants automatic ephemeral preview environments for every pull request using vCluster. How do you architect dynamic ingress routing, host DNS wildcard propagation, and prevent port/path collisions across 80 simultaneous PRs?
Architectural solution for running isolated developer preview environments inside host Kubernetes clusters using vCluster without DNS name collisions or port conflicts.
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🛠️ Production Runbook & Step-by-Step Resolution
Configure Dynamic Subdomain Wildcards and ExternalDNS
Create a Route53 / Cloudflare DNS wildcard record *.preview.acme.internal pointing to your host cluster Ingress Controller LoadBalancer. Every PR environment automatically inherits this resolvable domain.
# ExternalDNS annotation on Host Ingress Controller ALB
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
annotations:
external-dns.alpha.kubernetes.io/hostname: '*.preview.acme.internal'Configure vCluster Ingress Sync to Host Cluster
In vcluster.yaml, enable ingress synchronization so that ingress resources created inside the virtual cluster are translated and created on the host cluster with unique PR hostnames.
# vcluster.yaml
sync:
ingresses:
enabled: true
# Host ingress rewrites domain: ${PR_NUMBER}-${SERVICE}.preview.acme.internalAutomate Ephemeral Lifecycle & TTL Cleanup via GitHub Actions
On PR open, deploy vCluster via Helm. On PR merge or close, trigger a cleanup action that deletes the namespace, releasing all underlying compute and EBS volumes immediately.
- Route traffic via wildcard DNS (*.preview.domain) mapped to the host cluster ingress controller.
- Configure vcluster.yaml to sync virtual Ingresses to the host cluster with unique PR-prefixed domains.
- Enforce strict 4-hour TTL controllers to automatically destroy idle PR preview clusters.