Use "docker load" to create "scratch" in hack/make/test-integration-cli (instead of implicitly pulling it from the index)

Creating the "docker save" tarball for "scratch" is pretty simple.  I've also extrapolated the "docker build -t busybox ." logic into a separate "hack/make/.ensure-busybox" file so that it can eventually be reused easier.

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)

hack/make/.ensure-busybox

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+if ! docker inspect busybox &> /dev/null; then
+	if [ -d /docker-busybox ]; then
+		source "$(dirname "$BASH_SOURCE")/.ensure-scratch"
+		( set -x; docker build -t busybox /docker-busybox )
+	else
+		( set -x; docker pull busybox )
+	fi
+fi

hack/make/.ensure-scratch

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+if ! docker inspect scratch &> /dev/null; then
+	# let's build a "docker save" tarball for "scratch"
+	# see https://github.com/dotcloud/docker/pull/5262
+	# and also https://github.com/dotcloud/docker/issues/4242
+	mkdir -p /docker-scratch
+	(
+		cd /docker-scratch
+		echo '{"scratch":{"latest":"511136ea3c5a64f264b78b5433614aec563103b4d4702f3ba7d4d2698e22c158"}}' > repositories
+		mkdir -p 511136ea3c5a64f264b78b5433614aec563103b4d4702f3ba7d4d2698e22c158
+		(
+			cd 511136ea3c5a64f264b78b5433614aec563103b4d4702f3ba7d4d2698e22c158
+			echo '{"id":"511136ea3c5a64f264b78b5433614aec563103b4d4702f3ba7d4d2698e22c158","comment":"Imported from -","created":"2013-06-13T14:03:50.821769-07:00","container_config":{"Hostname":"","Domainname":"","User":"","Memory":0,"MemorySwap":0,"CpuShares":0,"AttachStdin":false,"AttachStdout":false,"AttachStderr":false,"PortSpecs":null,"ExposedPorts":null,"Tty":false,"OpenStdin":false,"StdinOnce":false,"Env":null,"Cmd":null,"Image":"","Volumes":null,"WorkingDir":"","Entrypoint":null,"NetworkDisabled":false,"OnBuild":null},"docker_version":"0.4.0","architecture":"x86_64","Size":0}' > json
+			echo '1.0' > VERSION
+			tar -cf layer.tar --files-from /dev/null
+		)
+	)
+	( set -x; tar -cf /docker-scratch.tar -C /docker-scratch . )
+	( set -x; docker load --input /docker-scratch.tar )
+fi

hack/make/test-integration-cli

@@ -30,13 +30,7 @@ bundle_test_integration_cli() {
 	# pull the busybox image before running the tests
 	sleep 2
 
-	if ! docker inspect busybox &> /dev/null; then
-		if [ -d /docker-busybox ]; then
-			( set -x; docker build -t busybox /docker-busybox )
-		else
-			( set -x; docker pull busybox )
-		fi
-	fi
+	source "$(dirname "$BASH_SOURCE")/.ensure-busybox"
 
 	bundle_test_integration_cli