[PATCH v2 06/10] update debian initramfs in deterministic mode

[Felix Moessbauer <felix.moessbauer@siemens.com>]

This patch exports the SOURCE_DATE_EPOCH variable in the image install
task. By that, update-initramfs is switched into reproducible mode.
Before this patch, each trigger of update-initramfs created a new
non-deterministic version of the initramfs.

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
---
 meta/classes/image.bbclass | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index b86a428..063b9a3 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -304,6 +304,17 @@ python() {
 }
 
 
+# make generation of initramfs reproducible
+# note: this function is shared across multiple rootfs, but we only want to make the
+#       image rootfs reproducible. Otherwise changes of SOURCE_DATE_EPOCH would
+#       invalidate the SSTATE entries for most packages, even if they don't use the
+#       global SOURCE_DATE_EPOCH variable.
+rootfs_install_pkgs_install_prepend() {
+    if [ ! -z "${SOURCE_DATE_EPOCH}" ]; then
+        export SOURCE_DATE_EPOCH="${SOURCE_DATE_EPOCH}"
+    fi
+}
+
 # here we call a command that should describe your whole build system,
 # this could be "git describe" or something similar.
 # set ISAR_RELEASE_CMD to customize, or override do_mark_rootfs to do something
-- 
2.34.1