Script to cleanup Google Cloud - GCP - virtual machine images based on project and number of desired images

image-cleanup.sh

#!/bin/bash
# Script to cleanup GCP virtual machine images

# How many images of this family do we wish to retain
desired_images=8
image_project="PROJECTHERE"

clean_images()
{
  # Function to clean up images, set the default family to megatron base

  # Calculate how many images there are and how many images we need to delete to get to our desired image amount
  number_of_images=$(gcloud compute images list --filter="family=( ${image_family} )" --project=${image_project} | wc -l | xargs)
  images_to_delete=$((${number_of_images}-${desired_images}))


  echo ""
  echo "Total found images in ${image_family} family - $number_of_images"

  # Working variables
  loop=0

  # Iterate over all the listed images in family and project
  for image in $(gcloud compute images list --sort-by "creationTimestamp" --filter="family=( ${image_family} )" --project=${image_project} --format="value(NAME)" | cut -f1); do
    if [ $loop -ge $images_to_delete ]; then
      if [ $loop == 0 ]; then
        echo "No images to delete"
      fi
      echo "Images processed"
      echo ""
      break
    fi

    let "loop++"
    # Delete the image with no confirmation
    echo "deleting $image"
    gcloud compute images delete --project ${image_project} -q ${image}
  done
}

clean_images "IMAGE-FAMILY-NAME-HERE"

The documentation is slightly obscure on this, it should be fairly simple to do but these things never are. Hopefully this will help someone out!