Reloader

Mon, 01 Jan 2024 00:00:00 +0000

Reloader is a Kubernetes controller from Stakater that watches ConfigMaps and Secrets and automatically triggers rolling restarts of Deployments, StatefulSets, and DaemonSets when the watched resources change. Kubernetes does not do this natively — updating a ConfigMap does not restart pods that consume it, so configuration changes don’t take effect until the next deploy.

Usage

Annotate a Deployment to watch a specific ConfigMap or Secret:

apiVersion: apps/v1
kind: Deployment
metadata:
 name: my-app
 annotations:
 reloader.stakater.com/auto: "true" # watch all referenced ConfigMaps/Secrets
 # OR be specific:
 configmap.reloader.stakater.com/reload: "my-config"
 secret.reloader.stakater.com/reload: "my-secret"

When the ConfigMap or Secret changes, Reloader detects it and triggers a rolling restart by updating a pod template annotation. The deployment rolls out new pods that pick up the updated configuration.

Installation

helm repo add stakater https://stakater.github.io/stakater-charts
helm install reloader stakater/reloader -n reloader --create-namespace

Why not use a hash annotation manually

The common alternative is to inject a hash of the ConfigMap into the pod template annotations via Helm or Kustomize — when the hash changes, Kubernetes rolls the deployment. This works but requires build-time tooling. Reloader handles it at runtime without any changes to the deployment pipeline.

Configmap on Backend Engineering Strategy Tools

Reloader

Usage

Installation

Why not use a hash annotation manually

Resources