ability to specify platform arch for air gap install

Signed-off-by: David Gaster <dngaster@gmail.com>
(cherry picked from commit a601ecc468)

scripts/save-images.sh

@@ -15,6 +15,11 @@ while [[ $# -gt 0 ]]; do
 		shift # past argument
 		shift # past value
 		;;
+		-p|--platform)
+		platform="$2"
+		shift # past argument
+		shift # past value
+		;;
 		-h|--help)
 		help="true"
 		shift
@@ -28,8 +33,9 @@ while [[ $# -gt 0 ]]; do
 done
 
 usage () {
-	echo "USAGE: $0 [--image-list longhorn-images.txt] [--images longhorn-images.tar.gz]"
+	echo "USAGE: $0 [--image-list longhorn-images.txt] [--images longhorn-images.tar.gz] [--platform linux/amd64]"
 	echo "  [-l|--images-list path] text file with list of images. 1 per line."
+	echo "  [-p|--platform linux/arch] if using images-list path, pulls the image with the specified platform"
 	echo "  [-i|--images path] tar.gz generated by docker save. If this flag is empty, the script does not export images to a tar.gz file"
 	echo "  [-h|--help] Usage message"
 }
@@ -42,7 +48,11 @@ fi
 set -e -x
 
 for i in $(cat ${list}); do
+    if [ -n "$platform" ]; then
+        docker pull ${i} --platform $platform
+    else
         docker pull ${i}
+    fi
 done
 
 if [[ $images ]]; then