A demo program to trigger a memory leak in k8s.io/client-go v0.26.x and newer.
This was written to report an issue to Kubernetes kubernetes/kubernetes#118703
CAUTION: this is not a tut0riaI on making a connection pool or using k8s API. This program is intentionally broken (and because I wrote it in a hurry, it might be also unintentionally broken).
If you create a rest.Config with custom Dial function, it breaks the cache in k8s.io/client-go/transport/cache.go. The cache creates a new entry every time you request a new ClientSet with this config, resulting in potentially infinite memory leak.
build with go build memory_leak_demo.
Options:
-kubeconfig filename: A path to valid kubeconfig file for a running Kubernetes cluster.
Kubeconfig needs the permission to list cluster nodes. Default ~/.kube/config.
Also can be set via KUBECONFIG env variable.
-pprof ip:port: A TCP port to listen for pprof HTTP requests, e.q. 127.0.0.1:21285.
See https://pkg.go.dev/net/http/pprof how to use this endpoint. This tool helps to verify the leak.
Default: HTTP pprof disabled.
-sleep seconds: Interval between k8s API queries. Smaller interval means faster leak.