Add alpine:3.16.0 for mirrorring and add ability to check if image mirrorred.

images/alpine.sh

@@ -0,0 +1,2 @@
+#!/usr/bin/env bash
+echo "alpine:3.16.0"

mirror.sh

@@ -51,9 +51,15 @@ function get_amd64_image() {
 	image_name=$(echo "${image}" | cut -d":" -f 1)
 	image_version=$(echo "${image}" | cut -d":" -f 2)
 
+	# Check if amd64 layers should be fetched.
+	if docker manifest inspect "${REMOTE_IMAGE}-amd64" &> /dev/null; then
+		echo -e "\t* Layers for amd64 architecture for this image exist."
+
+		return
+	fi
+
 	echo -ne "\t* Getting amd64 layers... "
 
-	# arm64 layers might be missing. So we just put "FAIL!" here and do nothing else.
 	if ! docker pull --platform=linux/amd64 "${image}" &> /dev/null; then
 		echo "FAIL!"
 
@@ -79,6 +85,13 @@ function get_arm64_image() {
 	image_name=$(echo "${image}" | cut -d":" -f 1)
 	image_version=$(echo "${image}" | cut -d":" -f 2)
 
+	# Check if arm64 layers should be fetched.
+	if docker manifest inspect "${REMOTE_IMAGE}-arm64" &> /dev/null; then
+		echo -e "\t* Layers for arm64 architecture for this image exist."
+
+		return
+	fi
+
 	echo -ne "\t* Getting arm64 layers... "
 
 	# arm64 layers might be missing. So we just put "FAIL!" here and do nothing else.