Kubefeeds Team A dedicated and highly skilled team at Kubefeeds, driven by a passion for Kubernetes and Cloud-Native technologies, delivering innovative solutions with expertise and enthusiasm.

πŸš€ How I Merged Multiple Kubernetes Clusters with Zero Downtime

1 min read

Managing too many Kubernetes clusters? 😩 Been there. When your infra grows wild, merging clusters can reduce costs, simplify security, and cut DevOps headachesβ€”but only if done right.

Here’s how I successfully consolidated multiple clusters into one without breaking production.

πŸ”₯ Why Merge Kubernetes Clusters?
Less Maintenance β†’ No more juggling dozens of separate monitoring, logging, and security setups.

Lower Costs β†’ One optimized cluster is cheaper than several underutilized ones.

Better Security β†’ Centralized policies reduce the risk of misconfiguration.
πŸ”Ή 1. Map Your Microservices
Before migration, know your dependencies. Example:
βœ… star-app β†’ Consumes API, sends messages to RabbitMQ
βœ… comet-app β†’ Listens to RabbitMQ, writes to Elasticsearch

πŸ”‘ Lesson: Move dependent services together or risk unexpected failures.

πŸ”Ή 2. Unify Your Monitoring & Logging
I moved Prometheus, Grafana, and RabbitMQ into a single cluster:

additionalScrapeConfigs:
  - job_name: star-service
    static_configs:
      - targets: ['star-app.star-namespace:8080']

βœ… Now, one dashboard tracks everything.

πŸ”Ή 3. Fix Traffic Routing (Ingress / Istio)

πŸ”΄ Before: Each cluster had its own LoadBalancer (πŸ’Έ $$$).
🟒 After: Unified traffic with two gateways:

External Gateway β†’ For public requests
Internal Gateway β†’ For microservices

kind: VirtualService
spec:
  hosts:
    - "star.mydomain.org"
  gateways:
    - external-gateway
  http:
    - match:
        - uri:
            prefix: /
      route:
        - destination:
            host: star-service
            port: 8080

βœ… Fewer LoadBalancers, faster traffic routing.

πŸ”Ή 4. Strengthen Security

πŸ”’ Before: Cluster-wide open access 😱
πŸ” After:
βœ” Firewall rules to restrict external traffic
βœ” JWT-based authentication for API access
βœ” NetworkPolicies to control pod-to-pod communication

kind: NetworkPolicy
spec:
  ingress:
    - from:
        - namespaceSelector:
            matchLabels:
              istio-injection: enabled
      ports:
        - protocol: TCP
          port: 8080

βœ… Locked down. No more unnecessary exposure.

πŸ”Ή 5. Seamless Migration

βœ… Deploy new cluster first β†’ Debug everything in test
βœ… Gradually switch traffic β†’ Use DNS/load balancers to transition traffic
βœ… Decommission old clusters β†’ After validation
The result? πŸš€
βœ… 40% cost savings
βœ… Unified monitoring & security
βœ… No downtime

Want the full breakdown? πŸ”₯
πŸ‘‰ Read the complete guide on Medium:
https://medium.datadriveninvestor.com/how-i-merged-multiple-kubernetes-clusters-with-zero-downtime-7c62f0a8c050
πŸ’¬ Have you consolidated clusters before? What was your biggest challenge? Let’s discuss in the comments! πŸš€

Kubefeeds Team A dedicated and highly skilled team at Kubefeeds, driven by a passion for Kubernetes and Cloud-Native technologies, delivering innovative solutions with expertise and enthusiasm.