From 4b424bdfdbbe16b6e41f6cd1de75a51e3799cf94 Mon Sep 17 00:00:00 2001 From: Richard Purdie Date: Thu, 14 Oct 2021 12:34:17 +0100 Subject: reproducible: Merge code into base.bbclass Reproducibility is here to stay and needs to be part of our default workflow. Move the remaining code to base.bbclass so it is always a first class citizen and it is clear people need to be mindful of it. (From OE-Core rev: abb0671d2cebfd7e8df94796404bbe9c7f961058) Signed-off-by: Richard Purdie --- meta/lib/oe/reproducible.py | 51 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) (limited to 'meta/lib/oe') diff --git a/meta/lib/oe/reproducible.py b/meta/lib/oe/reproducible.py index a5000574cf..4fb99d963c 100644 --- a/meta/lib/oe/reproducible.py +++ b/meta/lib/oe/reproducible.py @@ -5,6 +5,57 @@ import os import subprocess import bb +# For reproducible builds, this code sets the default SOURCE_DATE_EPOCH in each +# component's build environment. The format is number of seconds since the +# system epoch. +# +# Upstream components (generally) respect this environment variable, +# using it in place of the "current" date and time. +# See https://reproducible-builds.org/specs/source-date-epoch/ +# +# The default value of SOURCE_DATE_EPOCH comes from the function +# get_source_date_epoch_value which reads from the SDE_FILE, or if the file +# is not available will use the fallback of SOURCE_DATE_EPOCH_FALLBACK. +# +# The SDE_FILE is normally constructed from the function +# create_source_date_epoch_stamp which is typically added as a postfuncs to +# the do_unpack task. If a recipe does NOT have do_unpack, it should be added +# to a task that runs after the source is available and before the +# do_deploy_source_date_epoch task is executed. +# +# If a recipe wishes to override the default behavior it should set it's own +# SOURCE_DATE_EPOCH or override the do_deploy_source_date_epoch_stamp task +# with recipe-specific functionality to write the appropriate +# SOURCE_DATE_EPOCH into the SDE_FILE. +# +# SOURCE_DATE_EPOCH is intended to be a reproducible value. This value should +# be reproducible for anyone who builds the same revision from the same +# sources. +# +# There are 4 ways the create_source_date_epoch_stamp function determines what +# becomes SOURCE_DATE_EPOCH: +# +# 1. Use the value from __source_date_epoch.txt file if this file exists. +# This file was most likely created in the previous build by one of the +# following methods 2,3,4. +# Alternatively, it can be provided by a recipe via SRC_URI. +# +# If the file does not exist: +# +# 2. If there is a git checkout, use the last git commit timestamp. +# Git does not preserve file timestamps on checkout. +# +# 3. Use the mtime of "known" files such as NEWS, CHANGLELOG, ... +# This works for well-kept repositories distributed via tarball. +# +# 4. Use the modification time of the youngest file in the source tree, if +# there is one. +# This will be the newest file from the distribution tarball, if any. +# +# 5. Fall back to a fixed timestamp (SOURCE_DATE_EPOCH_FALLBACK). +# +# Once the value is determined, it is stored in the recipe's SDE_FILE. + def get_source_date_epoch_from_known_files(d, sourcedir): source_date_epoch = None newest_file = None -- cgit v1.2.3-54-g00ecf