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Scaling

This guide explains how to scale Virtual MCP Server (vMCP) deployments.

Vertical scaling​

Vertical scaling (increasing CPU/memory per instance) is the simplest approach and works for all use cases, including stateful backends.

To increase resources, configure podTemplateSpec in your VirtualMCPServer:

spec:
  podTemplateSpec:
    spec:
      containers:
        - name: vmcp
          resources:
            requests:
              cpu: '500m'
              memory: 512Mi
            limits:
              cpu: '1'
              memory: 1Gi

Vertical scaling is recommended as the starting point for most deployments.

Horizontal scaling​

Horizontal scaling (adding more replicas) can improve availability and handle higher request volumes.

How to scale horizontally​

The VirtualMCPServer CRD does not have a replicas field. The operator creates a Deployment named vmcp-<NAME> (where <NAME> is your VirtualMCPServer name) with 1 replica and preserves the replicas count, allowing you to manage scaling separately.

Option 1: Manual scaling

kubectl scale deployment vmcp-<vmcp-name> -n <NAMESPACE> --replicas=3

Option 2: Autoscaling with HPA

kubectl autoscale deployment vmcp-<vmcp-name> -n <NAMESPACE> \
  --min=2 --max=5 --cpu-percent=70

When horizontal scaling is challenging​

Horizontal scaling works well for stateless backends (fetch, search, read-only operations) where sessions can be resumed on any instance.

However, stateful backends make horizontal scaling difficult:

  • Stateful backends (Playwright browser sessions, database connections, file system operations) require requests to be routed to the same vMCP instance that established the session
  • Requires session affinity configuration (which may not work reliably through proxies)
  • Session resumption may not work reliably for stateful backends

For stateful backends, vertical scaling or dedicated vMCP instances per team/use case are recommended instead of horizontal scaling.