Add script to clean ip older images

Signed-off-by: Avi Deitcher <avi@deitcher.net>

scripts/cleanup-older-images.sh

@@ -0,0 +1,88 @@
+#!/bin/sh
+set -e
+
+##
+#
+# script to remove all older linuxkit images
+# see usage() for usage and functionality
+#
+
+usage() {
+    cat >&2 <<EOF
+$0 [-n] <base> <versions>
+
+Prune any images that start with <base> except the <versions> most recent versions.
+[-n] = dry-run, but report what it would remove and leave.
+
+Examples:
+  $0 linuxkit 2
+        will remove all versions of any image starting with linuxkit except for the 2 most recent of each
+        would match "linuxkit/foo" and ALSO "linuxkitprojects/foo"
+
+  $0 linuxkit/ 2
+        will remove all versions of any image starting with linuxkit/ except for the 2 most recent of each
+        would match "linuxkit/foo" but NOT "linuxkitprojects/foo"
+
+  $0 linuxkit/sshd 3
+        will remove all versions of linuxkit/sshd except for the 3 most recent
+
+EOF
+}
+
+
+# backwards compatibility
+dryrun=false
+if [ "$1" = "-n" ]; then
+  dryrun=true
+  set -- "$2" "$3"
+fi
+
+# sufficient arguments
+if [ $# -ne 2 ] ; then
+    usage
+    exit 1
+fi
+
+imagebase="$1"
+versions="$2"
+unversions=$(( $versions + 1))
+
+# make sure the imagebase is good
+case "$imagebase" in
+  # has a slash in it
+  */*)
+    testimage="$imagebase*"
+    ;;
+    # no slash in it
+  *)
+    testimage="$imagebase*/*"
+    ;;
+esac
+
+# find all of our images
+IMAGELIST=$(docker image ls --filter=reference="$testimage"':*' --format '{{.Repository}} {{.Tag}} {{.CreatedAt}}')
+
+# find unique names for all images
+uniqueimages=$(echo "$IMAGELIST" | awk '{print $1}' | sort | uniq)
+
+# now go through each image, find the list
+for img in $uniqueimages; do
+  # get the unique list of each, and sort by date
+  sortedlist=$(echo "$IMAGELIST" | grep -w $img | sort -k 3,3 -r)
+  # now split
+  tokeep=$(echo "$sortedlist" | head -$versions | awk '{printf "%s:%s\t",$1,$2; $1=$2=""; print $0}')
+  todelete=$(echo "$sortedlist" | tail -n +$unversions | awk '{print $1":"$2}')
+  todeletedates=$(echo "$sortedlist" | tail -n +$unversions | awk '{printf "%s:%s\t",$1,$2; $1=$2=""; print $0}')
+
+  echo "$tokeep" | while read i; do
+    echo "KEEP\t$i"
+  done
+  if [ -n "$todeletedates" ]; then
+    echo "$todeletedates" | while read i; do
+      echo "DELETE\t$i"
+    done
+    if ! "$dryrun"; then
+      docker image rm $todelete
+    fi
+  fi
+done