build: don't store timestamps in APK packages

This commit statically sets SOURCE_DATE_EPOCH to 0, which causes `apk mkpkg` to
drop the date from generated packages. This improves reproducibility while
leaving package specific SOURCE_DATE_EPOCH untouched. The latter can be
interesting for i.e. packages like busybox, which prominently show that date on
the login shell.

Without this commit, packages that live inside feed repositories (openwrt.git,
packages.git etc) like `mtd` or `attendedsysupgrade-common` would have random
timestamps since no "full" git log was available.

Below an example with different source dates (0, 1):

│  0755  root:wheel    -                           -  /
│  0755  root:wheel    -                           -  lib/
│  0755  root:wheel    -                           -  lib/apk/
│  0755  root:wheel    -                           -  lib/apk/packages/
│ -0644  root:wheel    1970-01-01T00:00:01Z       10  lib/apk/packages/mtd.list
│ +0644  root:wheel    -                          10  lib/apk/packages/mtd.list
│  0755  root:wheel    -                           -  sbin/
│ -0755  root:wheel    1970-01-01T00:00:01Z    24595  sbin/mtd
│ +0755  root:wheel    -                       24595  sbin/mtd

Link: https://github.com/openwrt/openwrt/pull/24005
Signed-off-by: Paul Spooren <mail@aparcar.org>

diff --git a/include/package-pack.mk b/include/package-pack.mk
index 493619f7aa1e8117142c085bc13d31d0ccee2b77..5dc69139b3819bac5a151dd7386c0fd8396c2db7 100644 (file)
--- a/include/package-pack.mk
+++ b/include/package-pack.mk
@@ -605,7 +605,7 @@ else
                exit 1; \
        fi
 
-       $(FAKEROOT) $(STAGING_DIR_HOST)/bin/apk mkpkg \
+       SOURCE_DATE_EPOCH=0 $(FAKEROOT) $(STAGING_DIR_HOST)/bin/apk mkpkg \
          --info "name:$(1)$$(ABIV_$(1))" \
          --info "version:$(VERSION)" \
          $$(if $$(APK_TAGS_$(1)),--info "tags:$$(APK_TAGS_$(1))") \