Chroot seems to work for simple enough builds

testdata/chroot-simple/Dockerfile

@@ -0,0 +1,3 @@
+FROM debian:9
+RUN echo "ASD" > /asd
+RUN cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 32 | head -n 1

tools/scripts/makisu_chroot.sh

@@ -0,0 +1,55 @@
+#! /bin/bash
+
+set -e
+
+[ -z "$1" ] && echo "Must at least provide context of build" && exit 1
+
+CHROOT=${CHROOT_LOCATION:-$HOME/.makisu-chroot-$RANDOM}
+SSL_CERT_DIR=${SSL_CERTS:-/etc/ssl/certs}
+CONTEXT=${@: -1}
+BUILD_VOLUMES="$CONTEXT:/context,$BUILD_VOLUMES"
+
+function makisu::prepare_internals () {
+    mkdir -p $CHROOT/makisu-internal/certs
+    cp $(which makisu) $CHROOT/makisu-internal/makisu
+    cat $SSL_CERT_DIR/* > $CHROOT/makisu-internal/certs/cacerts.pem
+}
+
+function makisu::prepare_dev () {
+    mkdir -p $CHROOT/dev
+    mknod -m 622 $CHROOT/dev/console c 5 1
+    mknod -m 666 $CHROOT/dev/null c 1 3
+    mknod -m 666 $CHROOT/dev/zero c 1 5
+    mknod -m 666 $CHROOT/dev/ptmx c 5 2
+    mknod -m 666 $CHROOT/dev/tty c 5 0
+    mknod -m 444 $CHROOT/dev/random c 1 8
+    mknod -m 444 $CHROOT/dev/urandom c 1 9
+    chown root:tty $CHROOT/dev/{console,ptmx,tty}
+}
+
+function makisu::prepare_etc () {
+    mkdir -p $CHROOT/etc
+    cp /etc/*.conf $CHROOT/etc/
+}
+
+function makisu::prepare_volumes () {
+    for vol in $(sed "s/,/ /g" <<< $BUILD_VOLUMES); do
+        from=$(cut -d ':' -f 1 <<< $vol)
+        to=$(cut -d ':' -f 2 <<< $vol)
+        echo "Copying volume $from to chroot directory $CHROOT/$to"
+        mkdir -p $CHROOT/$to
+        cp -r $from/* $CHROOT/$to
+    done
+}
+
+echo "Preparing chroot at $CHROOT"
+rm -rf $CHROOT
+
+makisu::prepare_internals
+makisu::prepare_etc
+makisu::prepare_dev
+makisu::prepare_volumes
+
+makisu_args=${@:1:$#-1}
+echo "Starting Makisu: makisu $makisu_args /context"
+chroot $CHROOT/ /makisu-internal/makisu $makisu_args /context