Reloader — Auto-Restart Kubernetes Pods on Config Changes

What it is

Reloader is a Kubernetes controller that watches for changes in ConfigMaps and Secrets, then triggers rolling upgrades on associated Deployments, StatefulSets, and DaemonSets. By default, Kubernetes does not restart pods when a mounted ConfigMap or Secret changes; Reloader fills that gap.

Reloader is for Kubernetes operators and platform engineers who need configuration changes to take effect without manual pod restarts or redeployment pipelines.

How it saves time or tokens

Without Reloader, teams must either manually restart pods after config changes, build custom controllers, or use workarounds like changing annotation checksums in Helm charts. Reloader handles this automatically by computing a hash of the ConfigMap or Secret data and updating a pod annotation when the hash changes, which triggers the Kubernetes rolling update mechanism.

How to use

1. Install Reloader via Helm: helm repo add stakater https://stakater.github.io/stakater-charts && helm install reloader stakater/reloader.
2. Add the annotation reloader.stakater.com/auto: 'true' to your Deployment, StatefulSet, or DaemonSet.
3. Update a ConfigMap or Secret; Reloader automatically triggers a rolling restart of the annotated workload.

Example

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
  annotations:
    reloader.stakater.com/auto: 'true'
spec:
  replicas: 3
  template:
    spec:
      containers:
        - name: app
          image: my-app:latest
          envFrom:
            - configMapRef:
                name: my-app-config

Related on TokRepo

• DevOps tools -- Kubernetes operational automation tools
• Automation tools -- infrastructure automation workflows

Common pitfalls

• Enabling Reloader on all workloads in a cluster without the annotation filter can cause unexpected rolling restarts during routine config changes.
• Reloader triggers restarts for any data change in the ConfigMap, including whitespace-only changes; be precise with config updates.
• In large clusters, Reloader's watch on all ConfigMaps and Secrets can consume significant API server resources; use namespace filtering.