ns-reloader

ns-reloader is a generic Kubernetes namespace watcher that automatically restarts a wrapped process when namespaces matching a specified label selector change. It dynamically updates an environment variable with the list of watched namespaces and gracefully restarts the wrapped process to reflect those changes.

Configuration

ns-reloader is configured via environment variables:

Flag	Environment Variable	Required	Description	Default
--namespace-selector	RELOADER_NAMESPACE_SELECTOR	Yes	Kubernetes label selector for namespaces to watch	n/a
--target-env-var	RELOADER_TARGET_ENV_KEY	No	Name of the environment variable to populate with the namespace list	WATCH_NAMESPACE
--termination-grace-period	RELOADER_TERMINATION_GRACE_PERIOD	No	Grace period for stopping the wrapped process	5s
--debounce-period	RELOADER_DEBOUNCE_PERIOD	No	Minimum time to wait between process restarts.	5s

Usage

ns-reloader wraps any process and manages its lifecycle based on namespace changes. You can use the -- separator to distinguish reloader options from the wrapped command.

reloader [OPTION] -- [COMMAND]...

Example: Wrapping KEDA Operator

This example shows how to wrap KEDA operator to dynamically manage autoscaling across namespaces labeled with keda.sh/enabled=true.

FROM ghcr.io/pfnet/ns-reloader AS base
FROM ghcr.io/kedacore/keda:2.17.2
COPY --from=base /reloader /reloader
ENTRYPOINT ["/reloader"]

apiVersion: apps/v1
kind: Deployment
metadata:
  name: keda-operator-with-reloader
  namespace: keda
spec:
  replicas: 1
  selector:
    matchLabels:
      app: keda-operator
  template:
    metadata:
      labels:
        app: keda-operator
    spec:
      serviceAccountName: keda-operator
      containers:
        - name: keda-operator
          image: <wapped_keda_operator_image>
          env:
            - name: RELOADER_NAMESPACE_SELECTOR
              value: "keda.sh/enabled=true"
            - name: RELOADER_TARGET_ENV_KEY
              value: "WATCH_NAMESPACE"
          command: ["/reloader"]
          args:
            - "/keda"
            - "--leader-elect"
            - "--zap-log-level=info"
            - "--zap-encoder=console"

License

Apache License 2.0