Quick Start

This tutorial demonstrates the functionality of Eraser and validates that non-running images are removed succesfully.

Deploy a DaemonSet

After following the install instructions, we'll apply a demo DaemonSet. For illustrative purposes, a DaemonSet is applied and deleted so the non-running images remain on all nodes. The alpine image with the 3.7.3 tag will be used in this example. This is an image with a known critical vulnerability.

First, apply the DaemonSet:

cat <<EOF | kubectl apply -f -
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: alpine
spec:
  selector:
    matchLabels:
      app: alpine
  template:
    metadata:
      labels:
        app: alpine
    spec:
      containers:
      - name: alpine
        image: docker.io/library/alpine:3.7.3
EOF

Next, verify that the Pods are running or completed. After the alpine Pods complete, you may see a CrashLoopBackoff status. This is expected behavior from the alpine image and can be ignored for the tutorial.

$ kubectl get pods
NAME          READY   STATUS      RESTARTS     AGE
alpine-2gh9c   1/1     Running     1 (3s ago)   6s
alpine-hljp9   0/1     Completed   1 (3s ago)   6s

Delete the DaemonSet:

$ kubectl delete daemonset alpine

Verify that the Pods have been deleted:

$ kubectl get pods
No resources found in default namespace.

To verify that the alpine images are still on the nodes, exec into one of the worker nodes and list the images. If you are not using a kind cluster or Docker for your container nodes, you will need to adjust the exec command accordingly.

List the nodes:

$ kubectl get nodes
NAME                 STATUS   ROLES           AGE   VERSION
kind-control-plane   Ready    control-plane   45m   v1.24.0
kind-worker          Ready    <none>          45m   v1.24.0
kind-worker2         Ready    <none>          44m   v1.24.0

List the images then filter for alpine:

$ docker exec kind-worker ctr -n k8s.io images list | grep alpine
docker.io/library/alpine:3.7.3                                                                             application/vnd.docker.distribution.manifest.list.v2+json sha256:8421d9a84432575381bfabd248f1eb56f3aa21d9d7cd2511583c68c9b7511d10 2.0 MiB   linux/386,linux/amd64,linux/arm/v6,linux/arm64/v8,linux/ppc64le,linux/s390x  io.cri-containerd.image=managed
docker.io/library/alpine@sha256:8421d9a84432575381bfabd248f1eb56f3aa21d9d7cd2511583c68c9b7511d10           application/vnd.docker.distribution.manifest.list.v2+json sha256:8421d9a84432575381bfabd248f1eb56f3aa21d9d7cd2511583c68c9b7511d10 2.0 MiB   linux/386,linux/amd64,linux/arm/v6,linux/arm64/v8,linux/ppc64le,linux/s390x  io.cri-containerd.image=managed

Automatically Cleaning Images

After deploying Eraser, it will automatically clean images in a regular interval. This interval can be set using the manager.scheduling.repeatInterval setting in the configmap. The default interval is 24 hours (24h). Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".

Eraser will schedule eraser pods to each node in the cluster, and each pod will contain 3 containers: collector, scanner, and remover that will run to completion.

$ kubectl get pods -n eraser-system
NAMESPACE            NAME                                         READY   STATUS      RESTARTS         AGE
eraser-system        eraser-kind-control-plane-sb789           0/3     Completed   0                26m
eraser-system        eraser-kind-worker-j84hm                  0/3     Completed   0                26m
eraser-system        eraser-kind-worker2-4lbdr                 0/3     Completed   0                26m
eraser-system        eraser-controller-manager-86cdb4cbf9-x8d7q   1/1     Running     0                26m

The collector container sends the list of all images to the scanner container, which scans and reports non-compliant images to the remover container for removal of images that are non-running. Once all pods are completed, they will be automatically cleaned up.

If you want to remove all the images periodically, you can skip the scanner container by setting the components.scanner.enabled value to false using the configmap. In this case, each collector pod will hold 2 containers: collector and remover.

$ kubectl get pods -n eraser-system
NAMESPACE            NAME                                         READY   STATUS      RESTARTS         AGE
eraser-system        eraser-kind-control-plane-ksk2b           0/2     Completed   0                50s
eraser-system        eraser-kind-worker-cpgqc                  0/2     Completed   0                50s
eraser-system        eraser-kind-worker2-k25df                 0/2     Completed   0                50s
eraser-system        eraser-controller-manager-86cdb4cbf9-x8d7q   1/1     Running     0                55s