A script to automatically remove unused images from a microk8s registry

registry_cleanup.sh

#!/bin/bash

# Set variables
REGISTRY_URL="localhost:32000"

get_in_use_images() {
  microk8s kubectl get pods --all-namespaces -o jsonpath='{.items[*].spec.containers[*].image}' | tr ' ' '\n' | sort | uniq
}

get_registry_images() {
  curl -s "http://${REGISTRY_URL}/v2/_catalog" | jq -r '.repositories[]'
}

# Get the list of images in use by Kubernetes pods
in_use_images=$(get_in_use_images)

# Get the list of images in the registry
registry_images=$(get_registry_images)

# Find images in the registry that are not in use
unused_images=()
for image in $registry_images; do
  image_used=false
  for in_use_image in $in_use_images; do
    if [[ "$in_use_image" == *"$image"* ]]; then
      image_used=true
      break
    fi
  done
  if ! $image_used; then
    unused_images+=("$image")
  fi
done

get_tags() {
  curl -s "http://${REGISTRY_URL}/v2/$1/tags/list" | jq -r '.tags[]'
}

get_digest() {
  curl -sI -H "Accept: application/vnd.docker.distribution.manifest.v2+json" "http://${REGISTRY_URL}/v2/$1/manifests/$2" | grep Docker-Content-Digest | awk '{print $2}' | tr -d '\r'
}

delete_tagged_image() {
  curl -sI -X DELETE "http://${REGISTRY_URL}/v2/$1/manifests/$2"
}

# Remove unused images from the registry
for unused_image in "${unused_images[@]}"; do
  echo "Removing unused image: $unused_image"
  # List all tags for the image
  tags=$(get_tags $unused_image)

  # Delete each tag of the image
  for tag in $tags; do
	digest=$(get_digest $unused_image $tag)
	echo "Deleting $unused_image:$tag with digest $digest"
	response=$(delete_tagged_image $unused_image $digest)
	echo "Deleted $unused_image:$tag with response $response"
  done

done

echo "Cleanup complete."