k8s-sidecar

What is k8s-sidecar?

The k8s-sidecar image is a lightweight utility container often deployed alongside applications to dynamically inject configuration. It continuously monitors Kubernetes ConfigMaps and Secrets within a namespace and writes their contents to a mounted volume inside the container.

This approach enables applications that cannot natively reload configurations from the Kubernetes API to consume updates without modification. For example, it is commonly used with logging and monitoring stacks, such as Grafana or Prometheus, where dashboards and rule files can be managed as ConfigMaps and automatically synced to disk.

By decoupling configuration management from application logic, k8s-sidecar simplifies dynamic configuration workflows in Kubernetes environments.

How to use this image

The k8s-sidecar image is typically run as a sidecar container in the same pod as the main application.

Examples:

<code><pre>apiVersion: v1
kind: Pod
metadata:
 name: grafana
spec:
 containers:
   - name: grafana
     image: grafana/grafana:latest
     volumeMounts:
       - name: dashboards
         mountPath: /var/lib/grafana/dashboards
   - name: sidecar
     image: quay.io/kiwigrid/k8s-sidecar:latest
     env:
       - name: LABEL
         value: grafana_dashboard
       - name: FOLDER
         value: /var/lib/grafana/dashboards
     volumeMounts:
       - name: dashboards
         mountPath: /var/lib/grafana/dashboards
 volumes:
   - name: dashboards
     emptyDir: {}</pre></code>

This example shows k8s-sidecar watching ConfigMaps labeled grafana_dashboard and writing them into Grafana’s dashboards folder.

Image variants

The k8s-sidecar image is generally published under quay.io/kiwigrid/k8s-sidecar and available in these forms:

k8s-sidecar:<version>

Version-pinned images (e.g., k8s-sidecar:1.27.0) are recommended for production to ensure predictable behavior.

k8s-sidecar:latest

Tracks the most recent stable release. Useful for testing but less reliable for long-term production use.

k8s-sidecar:dev / nightly

Built from the development branch. Intended for contributors or teams testing upcoming features.