diff --git a/alpine/.gitignore b/alpine/.gitignore
index eb87ef6a8..75aa11237 100644
--- a/alpine/.gitignore
+++ b/alpine/.gitignore
@@ -2,6 +2,7 @@
 *.tag
 *.iso
 *.vhd
+*.tar
 *.tar.gz
 /mobylinux-boot.vhdx
 /mobylinux.efi
diff --git a/alpine/Makefile b/alpine/Makefile
index 66c7ebd74..411d3ca78 100644
--- a/alpine/Makefile
+++ b/alpine/Makefile
@@ -22,6 +22,9 @@ PAD4_IMAGE=mobylinux/pad4@sha256:1ad26970698670373ee0bf374a06900f712a61b8038255e
 # Tag: d5711601eb5b89de0f052d87365e18388ff3f1b5
 TAR2INITRD_IMAGE=mobylinux/tar2initrd@sha256:58d377e65845f91400e173ce9fca93462f2f237947eef2b0d2c17bb4f2da5ee8
 
+# Tag: d56cde1558e3080e59a32e3cd7c7141baa601811
+TARTAR2INITRD_IMAGE=mobylinux/tartar2initrd@sha256:e1ad4522ff906d339da5f250b9ef6bffa5a70b4dec7d2cf7f7dbd0447b79352f
+
 # Tag: 77bc577875fb3a80ac2d14b70d1daa885bbf199c
 GCE_IMAGE=mobylinux/mkimage-gce@sha256:f9abf2eae20984b7dd3c1afb700b2c9c41e39e6e7c688c78348a51d0780d74cc
 
@@ -63,12 +66,12 @@ moby.img: Dockerfile mkinitrd.sh init $(ETCFILES)
 
 container.img:
 	$(MAKE) -j -C containers
-	tar cf - containers/*/rootfs containers/*/config.json | \
-		docker run --rm --read-only --net=none --log-driver=none --tmpfs /tmp -i $(TAR2INITRD_IMAGE) > $@
+	tar cf - $$(find containers -name container.tar) | \
+		docker run --rm --read-only --net=none --log-driver=none --tmpfs /tmp -i $(TARTAR2INITRD_IMAGE) > $@
 
 test.img:
 	$(MAKE) -j -C test
-	tar cf - test/rootfs test/config.json | \
+	cat test/container.tar | \
 		docker run --rm --read-only --net=none --log-driver=none --tmpfs /tmp -i $(TAR2INITRD_IMAGE) > $@
 
 initrd.img: moby.img container.img
diff --git a/alpine/containers/.gitignore b/alpine/containers/.gitignore
deleted file mode 100644
index a5731bdba..000000000
--- a/alpine/containers/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-rootfs
-config.json
diff --git a/alpine/containers/binfmt/Makefile b/alpine/containers/binfmt/Makefile
index 45df3cb63..e7b5a9255 100644
--- a/alpine/containers/binfmt/Makefile
+++ b/alpine/containers/binfmt/Makefile
@@ -1,20 +1,16 @@
+# Tag: 893c93bf54bc037f6952886330d5ba58746ace37
+RIDDLER=mobylinux/riddler@sha256:3d4a61555110be4b6e8ff6bcdcf5f8aa24d64564eb4162ea4e580d8916d083cc
+
 # Tag: c3312201a71982a820067a521e457a8c29aa7397
 BINFMT_IMAGE=mobylinux/binfmt@sha256:2d08969710368376d927b0fc51796a2c30c67070421d4eb1973a08a83f98181f
 
-default: config.json
+default: container.tar
 
-EXCLUDE=--exclude .dockerenv --exclude Dockerfile \
-	--exclude dev/console --exclude dev/pts --exclude dev/shm \
-	--exclude etc/hostname --exclude etc/hosts --exclude etc/mtab --exclude etc/resolv.conf
-
-config.json:
-	mkdir -p rootfs
-	CONTAINER=$$( docker create $(BINFMT_IMAGE) /dev/null ) && \
-	docker export $$CONTAINER | tar -xf - -C rootfs $(EXCLUDE) && \
-	docker rm $$CONTAINER && \
-	../riddler.sh --cap-drop all --read-only -v /proc/sys/fs/binfmt_misc:/binfmt_misc $(BINFMT_IMAGE) /usr/bin/binfmt -dir /etc/binfmt.d/ -mount /binfmt_misc >$@
+container.tar:
+	docker run --rm -v /var/run/docker.sock:/var/run/docker.sock $(RIDDLER) \
+	   $(BINFMT_IMAGE) /containers/binfmt --cap-drop all --read-only -v /proc/sys/fs/binfmt_misc:/binfmt_misc $(BINFMT_IMAGE) /usr/bin/binfmt -dir /etc/binfmt.d/ -mount /binfmt_misc >$@
 
 clean:
-	rm -rf rootfs config.json
+	rm -f container.tar
 
 .DELETE_ON_ERROR:
diff --git a/alpine/containers/riddler.sh b/alpine/containers/riddler.sh
deleted file mode 100755
index d3404b30a..000000000
--- a/alpine/containers/riddler.sh
+++ /dev/null
@@ -1,6 +0,0 @@
-#!/bin/sh
-
-# tag: 801f33408e43e6a22985aa994ab0bcba41659ec6
-RIDDLER=mobylinux/riddler@sha256:2dda30eb24ac531a9f2164e9592a21538b5841f2ca8459b0c190da46ea7dfafd
-
-docker run --rm -v /var/run/docker.sock:/var/run/docker.sock $RIDDLER "$@"
diff --git a/alpine/containers/rng-tools/Makefile b/alpine/containers/rng-tools/Makefile
index c254aefd2..62a99295d 100644
--- a/alpine/containers/rng-tools/Makefile
+++ b/alpine/containers/rng-tools/Makefile
@@ -1,20 +1,16 @@
+# Tag: 893c93bf54bc037f6952886330d5ba58746ace37
+RIDDLER=mobylinux/riddler@sha256:3d4a61555110be4b6e8ff6bcdcf5f8aa24d64564eb4162ea4e580d8916d083cc
+
 # Tag: 3dad6dd43270fa632ac031e99d1947f20b22eec9
 RNGD_IMAGE=mobylinux/rngd@sha256:1c93c1db7196f6f71f8e300bc1d15f0376dd18e8891c8789d77c8ff19f3a9a92
 
-default: config.json
+default: container.tar
 
-EXCLUDE=--exclude .dockerenv --exclude Dockerfile \
-	--exclude dev/console --exclude dev/pts --exclude dev/shm \
-	--exclude etc/hostname --exclude etc/hosts --exclude etc/mtab --exclude etc/resolv.conf
-
-config.json:
-	mkdir -p rootfs
-	CONTAINER=$$( docker create $(RNGD_IMAGE) /dev/null ) && \
-	docker export $$CONTAINER | tar -xf - -C rootfs $(EXCLUDE) && \
-	docker rm $$CONTAINER && \
-	../riddler.sh --cap-drop all --cap-add SYS_ADMIN --read-only --oom-score-adj -800 $(RNGD_IMAGE) /bin/tini /usr/sbin/rngd -f >$@
+container.tar:
+	docker run --rm -v /var/run/docker.sock:/var/run/docker.sock $(RIDDLER) \
+	  $(RNGD_IMAGE) /containers/rngd --cap-drop all --cap-add SYS_ADMIN --read-only --oom-score-adj -800 $(RNGD_IMAGE) /bin/tini /usr/sbin/rngd -f >$@
 
 clean:
-	rm -rf rootfs config.json
+	rm -f container.tar
 
 .DELETE_ON_ERROR:
diff --git a/alpine/test/.gitignore b/alpine/test/.gitignore
deleted file mode 100644
index a5731bdba..000000000
--- a/alpine/test/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-rootfs
-config.json
diff --git a/alpine/test/Makefile b/alpine/test/Makefile
index 00c5b88b0..a42789122 100644
--- a/alpine/test/Makefile
+++ b/alpine/test/Makefile
@@ -1,20 +1,20 @@
+# Tag: 893c93bf54bc037f6952886330d5ba58746ace37
+RIDDLER=mobylinux/riddler@sha256:3d4a61555110be4b6e8ff6bcdcf5f8aa24d64564eb4162ea4e580d8916d083cc
+
 # Tag: e79cbcc45b715cea7047a802944b478a7b5a906a
 TEST_IMAGE=mobylinux/test@sha256:bc9403a9fc7aa5298f92c83d1e3423e804097f08dbba623e076c1728666f6b73
 
-default: config.json
+default: container.tar
 
-EXCLUDE=--exclude .dockerenv --exclude Dockerfile \
-	--exclude dev/console --exclude dev/pts --exclude dev/shm \
-	--exclude etc/hostname --exclude etc/hosts --exclude etc/mtab --exclude etc/resolv.conf
-
-config.json:
-	mkdir -p rootfs
-	CONTAINER=$$( docker create $(TEST_IMAGE) /dev/null ) && \
-	docker export $$CONTAINER | tar -xf - -C rootfs $(EXCLUDE) && \
-	docker rm $$CONTAINER && \
-	../containers/riddler.sh --cap-drop all --cap-add SYS_ADMIN -e HOME=/tmp -v /tmp:/tmp -v /var/run/docker.sock:/var/run/docker.sock:ro -v /usr/bin/docker:/usr/bin/docker:ro -v /etc/resolv.conf:/etc/resolv.conf:ro --net host --read-only $(TEST_IMAGE) /bin/sh /bin/test.sh >$@
+container.tar:
+	docker run --rm -v /var/run/docker.sock:/var/run/docker.sock $(RIDDLER) \
+	  $(TEST_IMAGE) /test --cap-drop all --cap-add SYS_ADMIN -e HOME=/tmp \
+	  -v /tmp:/tmp -v /var/run/docker.sock:/var/run/docker.sock:ro \
+	  -v /usr/bin/docker:/usr/bin/docker:ro \
+	  -v /etc/resolv.conf:/etc/resolv.conf:ro \
+	  --net host --read-only $(TEST_IMAGE) /bin/sh /bin/test.sh >$@
 
 clean:
-	rm -rf rootfs config.json
+	rm -f container.tar
 
 .DELETE_ON_ERROR:
diff --git a/base/riddler/Dockerfile b/base/riddler/Dockerfile
index 92394a073..2f194dd4f 100644
--- a/base/riddler/Dockerfile
+++ b/base/riddler/Dockerfile
@@ -9,6 +9,7 @@ RUN \
   jq \
   linux-headers \
   musl-dev \
+  tar \
   && true
 
 COPY Dockerfile /
diff --git a/base/riddler/Makefile b/base/riddler/Makefile
index 916455efa..1a6970ef0 100644
--- a/base/riddler/Makefile
+++ b/base/riddler/Makefile
@@ -8,11 +8,11 @@ default: push
 hash: Dockerfile riddler.sh
 	DOCKER_CONTENT_TRUST=1 docker pull $(BASE)
 	tar cf - $^ | docker build --no-cache -t $(IMAGE):build -
-	docker run --entrypoint=/bin/sh --rm $(IMAGE):build -c 'cat /Dockerfile /usr/bin/riddler.sh /lib/apk/db/installed | sha1sum' | sed 's/ .*//' > hash
+	docker run --entrypoint=/bin/sh --rm $(IMAGE):build -c 'cat /Dockerfile /usr/bin/riddler.sh /lib/apk/db/installed | sha1sum' | sed 's/ .*//' > $@
 
 push: hash
 	docker pull mobylinux/$(IMAGE):$(shell cat hash) || \
-		 (docker tag $(IMAGE):build mobylinux/$(IMAGE):latest && \
+		 (docker tag $(IMAGE):build mobylinux/$(IMAGE):$(shell cat hash) && \
 		  docker push mobylinux/$(IMAGE):$(shell cat hash))
 	docker rmi $(IMAGE):build
 	rm -f hash
diff --git a/base/riddler/riddler.sh b/base/riddler/riddler.sh
index 2c2f32cb5..2557af53a 100755
--- a/base/riddler/riddler.sh
+++ b/base/riddler/riddler.sh
@@ -2,6 +2,17 @@
 
 set -e
 
+# arguments are image name, prefix, then arguments passed to Docker
+# eg ./riddler.sh alpine:3.4 / --read-only alpine:3.4 ls
+# This script will output a tarball under prefix/ with rootfs and config.json
+
+IMAGE="$1"; shift
+PREFIX="$1"; shift
+
+cd /tmp
+mkdir -p /tmp/$PREFIX
+cd /tmp/$PREFIX
+
 # riddler always adds the apparmor options if this is not present
 EXTRA_OPTIONS="--security-opt apparmor=unconfined"
 
@@ -19,10 +30,25 @@ docker rm $CONTAINER > /dev/null
 # remove user namespaces
 # --read-only sets /dev ro
 # /sysfs ro unless privileged - cannot detect so will do if grant all caps
-# 
-cat config.json | \
+#
+mv config.json config.json.orig
+cat config.json.orig | \
   jq 'del(.process.rlimits)' | \
   jq 'del (.linux.resources.memory.swappiness)' | \
   jq 'del(.linux.uidMappings) | del(.linux.gidMappings) | .linux.namespaces = (.linux.namespaces|map(select(.type!="user")))' | \
   jq 'if .root.readonly==true then .mounts = (.mounts|map(if .destination=="/dev" then .options |= .+ ["ro"] else . end)) else . end' | \
-  jq '.mounts = if .process.capabilities | length != 38 then (.mounts|map(if .destination=="/sys" then .options |= .+ ["ro"] else . end)) else . end'
+  jq '.mounts = if .process.capabilities | length != 38 then (.mounts|map(if .destination=="/sys" then .options |= .+ ["ro"] else . end)) else . end' \
+  > config.json
+rm config.json.orig
+
+# extract rootfs
+EXCLUDE="--exclude .dockerenv --exclude Dockerfile \
+        --exclude dev/console --exclude dev/pts --exclude dev/shm \
+        --exclude etc/hostname --exclude etc/hosts --exclude etc/mtab --exclude etc/resolv.conf"
+mkdir -p rootfs
+CONTAINER="$(docker create $IMAGE /dev/null)"
+docker export "$CONTAINER" | tar -xf - -C rootfs $EXCLUDE
+docker rm "$CONTAINER" > /dev/null
+
+cd /tmp
+tar cf - .
diff --git a/base/tartar2initrd/Dockerfile b/base/tartar2initrd/Dockerfile
new file mode 100644
index 000000000..af6bdffa0
--- /dev/null
+++ b/base/tartar2initrd/Dockerfile
@@ -0,0 +1,12 @@
+FROM alpine:3.5
+
+RUN \
+  apk update && apk upgrade -a && \
+  apk add --no-cache \
+  libarchive-tools \
+  && true
+
+COPY . /
+
+ENTRYPOINT ["/bin/sh", "-c"]
+CMD ["/tartar2initrd.sh"]
diff --git a/base/tartar2initrd/Makefile b/base/tartar2initrd/Makefile
new file mode 100644
index 000000000..104c8c847
--- /dev/null
+++ b/base/tartar2initrd/Makefile
@@ -0,0 +1,29 @@
+.PHONY: tag push
+
+BASE=alpine:3.5
+IMAGE=tartar2initrd
+
+default: push
+
+hash: Dockerfile tartar2initrd.sh
+	DOCKER_CONTENT_TRUST=1 docker pull $(BASE)
+	tar cf - $^ | docker build --no-cache -t $(IMAGE):build -
+	docker run --rm --entrypoint=/bin/sh $(IMAGE):build -c "cat $^ /lib/apk/db/installed | sha1sum" | sed 's/ .*//' > $@
+
+push: hash
+	docker pull mobylinux/$(IMAGE):$(shell cat hash) || \
+		(docker tag $(IMAGE):build mobylinux/$(IMAGE):$(shell cat hash) && \
+		 docker push mobylinux/$(IMAGE):$(shell cat hash))
+	docker rmi $(IMAGE):build
+	rm -f hash
+
+tag: hash
+	docker pull mobylinux/$(IMAGE):$(shell cat hash) || \
+		docker tag $(IMAGE):build mobylinux/$(IMAGE):$(shell cat hash)
+	docker rmi $(IMAGE):build
+	rm -f hash
+
+clean:
+	rm -f hash
+
+.DELETE_ON_ERROR:
diff --git a/base/tartar2initrd/tartar2initrd.sh b/base/tartar2initrd/tartar2initrd.sh
new file mode 100755
index 000000000..64fe0462d
--- /dev/null
+++ b/base/tartar2initrd/tartar2initrd.sh
@@ -0,0 +1,40 @@
+#!/bin/sh
+
+set -e
+
+mkdir -p /tmp/input0 /tmp/input
+
+cd /tmp/input0
+
+# outer tarball
+bsdtar xf -
+
+cd /tmp/input
+
+# inner tarballs
+find /tmp/input0 \( -name '*.tar' -or -name '*.tgz' -or -name '*.tar.gz' \) -exec bsdtar xf '{}' \;
+
+find . | cpio -H newc -o | gzip -9 > ../initrd.img
+
+cd /tmp
+
+SIZE=$(stat -c "%s" initrd.img)
+SIZE4=$(( $SIZE / 4 \* 4 ))
+DIFF=$(( $SIZE - $SIZE4 ))
+[ $DIFF -ne 0 ] && DIFF=$(( 4 - $DIFF ))
+
+dd if=/dev/zero bs=1 count=$DIFF of=zeropad 2>/dev/null
+
+cat zeropad >> initrd.img
+
+SIZE=$(stat -c "%s" initrd.img)
+SIZE4=$(( $SIZE / 4 \* 4 )) 
+DIFF=$(( $SIZE - $SIZE4 ))
+
+if [ $DIFF -ne 0 ]
+then
+	echo "Bad alignment" >2
+	exit 1
+fi
+
+cat initrd.img