add wrapper script to set umask on downstream images

Dockerfile

@@ -100,6 +100,7 @@ RUN \
 	/app \
 	/config \
 	/defaults && \
+ mv /usr/bin/with-contenv /usr/bin/with-contenvb && \
  echo "**** cleanup ****" && \
  apt-get clean && \
  rm -rf \

Dockerfile.aarch64

@@ -100,6 +100,7 @@ RUN \
 	/app \
 	/config \
 	/defaults && \
+ mv /usr/bin/with-contenv /usr/bin/with-contenvb && \
  echo "**** add qemu ****" && \
  curl -o \
  /usr/bin/qemu-aarch64-static -L \

Dockerfile.armhf

@@ -100,6 +100,7 @@ RUN \
 	/app \
 	/config \
 	/defaults && \
+ mv /usr/bin/with-contenv /usr/bin/with-contenvb && \
  echo "**** add qemu ****" && \
  curl -o \
  /usr/bin/qemu-arm-static -L \

root/usr/bin/with-contenv

@@ -0,0 +1,7 @@
+#! /bin/bash
+if [[ -f /var/run/s6/container_environment/UMASK ]] && [[ "$(pwdx $$)" =~ "/run/s6/services/" ]]; then
+  umask $(cat /var/run/s6/container_environment/UMASK)
+  /usr/bin/with-contenvb "$@"
+else
+  /usr/bin/with-contenvb "$@"
+fi