Clean up old Podman images while keeping the newest version of each image

cleanup-podman-images.sh

#!/bin/sh
# Show usage information
show_help() {
  cat << EOF
Usage: $(basename "$0") [OPTIONS] [IMAGE_PATTERN]

Clean up old Podman images while keeping the newest version of each image.

Options:
  --dryrun    Show what would be removed without actually removing anything
  --help      Display this help message and exit

Arguments:
  IMAGE_PATTERN    Pattern to match image names (default: .*)

Examples:
  $(basename "$0")                           # Clean all images from any registry
  $(basename "$0") --dryrun                  # Show what would be removed (dry run)
  $(basename "$0") asia-east1-docker.pkg.dev        # Clean only asia-east1-docker.pkg.dev images
  $(basename "$0") --dryrun asia-east1-docker.pkg.dev         # Dry run for asia-east1-docker.pkg.dev images
EOF
  exit 0
}

# Parse arguments
IMAGE_PATTERN=".*"
DRYRUN=false

for arg in "$@"; do
  case "$arg" in
    --help|-h)
      show_help
      ;;
    --dryrun)
      DRYRUN=true
      ;;
    -*)
      # Skip other options
      ;;
    *)
      IMAGE_PATTERN="$arg"
      ;;
  esac
done

# Extract version from tag
extract_version() {
  echo "$1" | grep -o '[0-9]\+\(\.[0-9]\+\)*' 2>/dev/null || echo ""
}

# Get images
TMPFILE=$(mktemp)
RESULT_FILE=$(mktemp)
LATEST_FILE=$(mktemp)
CLEANUP_FILE=$(mktemp)

# Ensure cleanup on exit
cleanup() {
  rm -f "$TMPFILE" "$RESULT_FILE" "$LATEST_FILE" "$CLEANUP_FILE"
}
trap cleanup EXIT INT TERM

# Get all images matching pattern
podman image ls | grep "$IMAGE_PATTERN" > "$TMPFILE" || true

if [ ! -s "$TMPFILE" ]; then
  echo "No images found matching pattern: $IMAGE_PATTERN"
  exit 0
fi

# Process each line into repo, tag, id
cat "$TMPFILE" | while read -r line; do
  repo=$(echo "$line" | awk '{print $1}')
  tag=$(echo "$line" | awk '{print $2}')
  id=$(echo "$line" | awk '{print $3}')
  
  # Skip if no repo or tag
  [ -z "$repo" ] || [ -z "$tag" ] && continue
  
  # Store repo, tag, id
  echo "$repo|$tag|$id" >> "$RESULT_FILE"
done

# Find latest version for each repo and list images to remove
for repo in $(cat "$RESULT_FILE" | cut -d'|' -f1 | sort | uniq); do
  # Get all tags and find latest version
  latest_tag=""
  latest_ver=""
  
  # Get all tags for this repo
  for entry in $(grep "^$repo|" "$RESULT_FILE"); do
    tag=$(echo "$entry" | cut -d'|' -f2)
    
    # Skip 'latest' tag for version comparison
    if [ "$tag" != "latest" ]; then
      version=$(extract_version "$tag")
      if [ -n "$version" ]; then
        # If first version or newer
        if [ -z "$latest_ver" ] || [ "$(printf '%s\n%s' "$latest_ver" "$version" | sort -V | tail -n1)" = "$version" ]; then
          latest_ver="$version"
          latest_tag="$tag"
        fi
      fi
    fi
  done
  
  # Only proceed if we found a version tag
  if [ -n "$latest_tag" ]; then
    # Find old versions to remove
    remove_ids=""
    remove_tags=""
    
    for entry in $(grep "^$repo|" "$RESULT_FILE"); do
      tag=$(echo "$entry" | cut -d'|' -f2)
      id=$(echo "$entry" | cut -d'|' -f3)
      
      if [ "$tag" != "$latest_tag" ] && [ "$tag" != "latest" ]; then
        remove_ids="$remove_ids $id"
        remove_tags="$remove_tags $tag"
      fi
    done
    
    # Clean up the lists
    remove_ids=$(echo "$remove_ids" | tr -s ' ' | sed 's/^ //')
    remove_tags=$(echo "$remove_tags" | tr -s ' ' | sed 's/^ //')
    
    # Only output if we found images to remove
    if [ -n "$remove_ids" ]; then
      
      echo "Repo: $repo"
      echo "  Latest: $latest_tag"
      echo "  Remove: $remove_tags"
      echo "  Command: podman image rm -f $remove_ids"
      
      if [ "$DRYRUN" = false ]; then
        # shellcheck disable=SC2086
        podman image rm -f $remove_ids
      fi
    fi
  fi
done