Managing too many Kubernetes clusters? π© Been there. When your infra grows wild, merging clusters can reduce costs, simplify security, and cut DevOps headachesβbut only if done right.
Hereβs how I successfully consolidated multiple clusters into one without breaking production.
π₯ 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.
πΉ 1. Map Your Microservices
Before migration, know your dependencies. Example:
β
star-app β Consumes API, sends messages to RabbitMQ
β
comet-app β Listens to RabbitMQ, writes to Elasticsearch
π Lesson: Move dependent services together or risk unexpected failures.
πΉ 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']
β Now, one dashboard tracks everything.
πΉ 3. Fix Traffic Routing (Ingress / Istio)
π΄ Before: Each cluster had its own LoadBalancer (πΈ $$$).
π’ 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
β Fewer LoadBalancers, faster traffic routing.
πΉ 4. Strengthen Security
π Before: Cluster-wide open access π±
π After:
β Firewall rules to restrict external traffic
β JWT-based authentication for API access
β NetworkPolicies to control pod-to-pod communication
kind: NetworkPolicy
spec:
ingress:
- from:
- namespaceSelector:
matchLabels:
istio-injection: enabled
ports:
- protocol: TCP
port: 8080
β Locked down. No more unnecessary exposure.
πΉ 5. Seamless Migration
β
Deploy new cluster first β Debug everything in test
β
Gradually switch traffic β Use DNS/load balancers to transition traffic
β
Decommission old clusters β After validation
The result? π
β
40% cost savings
β
Unified monitoring & security
β
No downtime
Want the full breakdown? π₯
π Read the complete guide on Medium:
https://medium.datadriveninvestor.com/how-i-merged-multiple-kubernetes-clusters-with-zero-downtime-7c62f0a8c050
π¬ Have you consolidated clusters before? What was your biggest challenge? Letβs discuss in the comments! π