krar

Kubernetes Resources Auto Rollout aka krar

krar is a simple chart for refreshing images using floating tags on selected resources. Can be considered as a lightweight Keel alternative.

The main use case is when your Kubernetes cluster is running applications/services using major or minor image versions (floating tags) you want up to date.

[!WARNING] Triggering that restart affects resource availability if:

• There is only one replica of the resource,
• The image version is too open and brings breaking changes risk (like latest or usually major versions).

[!IMPORTANT] Only resources with imagePullPolicy set to Always will work.

It’s possible to define multiple jobs to handle resources to restart in specific ways.

krar doesn’t log events clearly nor annotate restart resources yet.

What’s inside?

No dependency required.

• ServiceAccount
• CluterRole/ClusterRoleBinding with GET, PATCH and LIST permissions on "", "apps" (deployments, daemonsets, statefulsets only)
• As many CronJob you need

How to mark my resource for automatic rollout?

With default values, you can add the following label on your Deployment, DaemonSet and StatefulSet resources:

krar.slash-mnt.com/rollout-policy: once-a-month

to allow auto rollout using the job named once-a-month.

Example:

# From https://kubernetes.io/docs/concepts/workloads/controllers/deployment/
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
    krar.slash-mnt.com/rollout-policy: once-a-month
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.25
        ports:
        - containerPort: 80

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