Image build time improvements (#10104)

* [build]: Patch debootstrap to not unmount the host's /proc filesystem

Currently, when the final image is being built (sonic-vs.img.gz,
sonic-broadcom.bin, or similar), each invocation of sudo in the
build_debian.sh script takes 0.8 seconds to run and execute the actual
command. This is because the /proc filesystem in the slave container has
been unmounted somehow. This is happening when debootstrap is running,
and it incorrectly unmounts the host's (in our case, the slave
container's) /proc filesystem because in the new image being built,
/proc is a symlink to the host's (the slave container's) /proc. Because
of that, /proc is gone, and each invocation of sudo adds 0.8 seconds
overhead. As a side effect, docker exec into the slave container during
this time will fail, because /proc/self/fd doesn't exist anymore, and
docker exec assumes that that exists.

Debootstrap has fixed this in 1.0.124 and newer, so backport the patch
that fixes this into the version that Bullseye has.

Signed-off-by: Saikrishna Arcot <sarcot@microsoft.com>

* [build_debian.sh]: Use eatmydata to speed up deb package installations

During package installations, dpkg calls fsync multiples times (for each
package) to ensure that tht efiles are written to disk, so that if
there's some system crash during package installation, then it is in at
least a somewhat recoverable state. For our use case though, we're
installing packages in a chroot in fsroot-* from a slave container and
then packaging it into an image. If there were a system crash (or even
if docker crashed), the fsroot-* directory would first be removed, and
the process would get restarted. This means that the fsync calls aren't
really needed for our use case.

The eatmydata package includes a library that will block/suppress the
use of fsync (and similar) system calls from applications and will
instead just return success, so that the application is not blocked on
disk writes, which can instead happen in the background instead as
necessary. If dpkg is run with this library, then the fsync calls that
it does will have no effect.

Therefore, install the eatmydata package at the beginning of
build_debian.sh and have dpkg be run under eatmydata for almost all
package installations/removals. At the end of the installation, remove
it, so that the final image uses dpkg as normal.

In my testing, this saves about 2-3 minutes from the image build time.

Signed-off-by: Saikrishna Arcot <sarcot@microsoft.com>

* Change ln syntax to use chroot

Signed-off-by: Saikrishna Arcot <sarcot@microsoft.com>

build_debian.sh

@@ -113,6 +113,12 @@ sudo cp files/apt/apt.conf.d/{81norecommends,apt-{clean,gzip-indexes,no-language
 ## Note: set lang to prevent locale warnings in your chroot
 sudo LANG=C chroot $FILESYSTEM_ROOT apt-get -y update
 sudo LANG=C chroot $FILESYSTEM_ROOT apt-get -y upgrade
+
+echo '[INFO] Install and setup eatmydata'
+sudo LANG=C chroot $FILESYSTEM_ROOT apt-get -y install eatmydata
+sudo LANG=C chroot $FILESYSTEM_ROOT ln -s /usr/bin/eatmydata /usr/local/bin/dpkg
+echo 'Dir::Bin::dpkg "/usr/local/bin/dpkg";' | sudo tee $FILESYSTEM_ROOT/etc/apt/apt.conf.d/00image-install-eatmydata > /dev/null
+
 echo '[INFO] Install packages for building image'
 sudo LANG=C chroot $FILESYSTEM_ROOT apt-get -y install makedev psmisc
 
@@ -586,6 +592,10 @@ scripts/collect_host_image_version_files.sh $TARGET_PATH $FILESYSTEM_ROOT
 # Remove GCC
 sudo LANG=C DEBIAN_FRONTEND=noninteractive chroot $FILESYSTEM_ROOT apt-get -y remove gcc
 
+# Remove eatmydata
+sudo rm $FILESYSTEM_ROOT/etc/apt/apt.conf.d/00image-install-eatmydata $FILESYSTEM_ROOT/usr/local/bin/dpkg
+sudo LANG=C DEBIAN_FRONTEND=noninteractive chroot $FILESYSTEM_ROOT apt-get -y remove eatmydata
+
 ## Clean up apt
 sudo LANG=C chroot $FILESYSTEM_ROOT apt-get -y autoremove
 sudo LANG=C chroot $FILESYSTEM_ROOT apt-get autoclean

rules/debootstrap.dep

@@ -0,0 +1,10 @@
+
+SPATH       := $($(DEBOOTSTRAP)_SRC_PATH)
+DEP_FILES   := $(SONIC_COMMON_FILES_LIST) rules/debootstrap.mk rules/debootstrap.dep
+DEP_FILES   += $(SONIC_COMMON_BASE_FILES_LIST)
+DEP_FILES   += $(shell git ls-files $(SPATH))
+
+$(DEBOOTSTRAP)_CACHE_MODE  := GIT_CONTENT_SHA
+$(DEBOOTSTRAP)_DEP_FLAGS   := $(SONIC_COMMON_FLAGS_LIST)
+$(DEBOOTSTRAP)_DEP_FILES   := $(DEP_FILES)
+

rules/debootstrap.mk

@@ -0,0 +1,9 @@
+# debootstrap package
+
+DEBOOTSTRAP_VERSION = 1.0.123
+
+export DEBOOTSTRAP_VERSION
+
+DEBOOTSTRAP = debootstrap_$(DEBOOTSTRAP_VERSION)_all.deb
+$(DEBOOTSTRAP)_SRC_PATH = $(SRC_PATH)/debootstrap
+SONIC_MAKE_DEBS += $(DEBOOTSTRAP)

slave.mk

@@ -992,6 +992,7 @@ $(addprefix $(TARGET_PATH)/, $(SONIC_INSTALLERS)) : $(TARGET_PATH)/% : \
         $$(addprefix $(TARGET_PATH)/,$$($$*_DOCKERS)) \
         $$(addprefix $(TARGET_PATH)/,$$(SONIC_PACKAGES_LOCAL)) \
         $$(addprefix $(FILES_PATH)/,$$($$*_FILES)) \
+        $(addsuffix -install,$(addprefix $(IMAGE_DISTRO_DEBS_PATH)/,$(DEBOOTSTRAP))) \
         $(if $(findstring y,$(ENABLE_ZTP)),$(addprefix $(IMAGE_DISTRO_DEBS_PATH)/,$(SONIC_ZTP))) \
         $(addprefix $(PYTHON_WHEELS_PATH)/,$(SONIC_UTILITIES_PY3)) \
         $(addprefix $(PYTHON_WHEELS_PATH)/,$(SONIC_PY_COMMON_PY2)) \

src/debootstrap/.gitignore

@@ -0,0 +1,3 @@
+debootstrap*.udeb
+debootstrap*.dsc
+debootstrap-*/

src/debootstrap/Makefile

@@ -0,0 +1,24 @@
+.ONESHELL:
+SHELL = /bin/bash
+.SHELLFLAGS += -e
+
+MAIN_TARGET = debootstrap_$(DEBOOTSTRAP_VERSION)_all.deb
+
+$(addprefix $(DEST)/, $(MAIN_TARGET)): $(DEST)/% :
+	# Remove any stale files
+	rm -rf ./debootstrap-$(DEBOOTSTRAP_VERSION) ./debootstrap*.{deb,udeb,dsc}
+
+	# Get source package
+	dget https://deb.debian.org/debian/pool/main/d/debootstrap/debootstrap_$(DEBOOTSTRAP_VERSION).dsc
+
+	# Build source and Debian packages
+	pushd debootstrap-$(DEBOOTSTRAP_VERSION)
+	patch -p1 -i ../proc-mount.patch
+	dpkg-buildpackage -rfakeroot -b -us -uc -j$(SONIC_CONFIG_MAKE_JOBS) --admindir $(SONIC_DPKG_ADMINDIR)
+	popd
+
+	# Move the newly-built .deb packages to the destination directory
+	mv $(DERIVED_TARGETS) $* $(DEST)/
+
+$(addprefix $(DEST)/, $(DERIVED_TARGETS)): $(DEST)/% : $(DEST)/$(MAIN_TARGET)
+

src/debootstrap/proc-mount.patch

@@ -0,0 +1,34 @@
+From 87cdebbcad6f4e16ba711227cbbbd70039f88752 Mon Sep 17 00:00:00 2001
+From: YunQiang Su <syq@debian.org>
+Date: Mon, 7 Sep 2020 09:29:37 +0800
+Subject: [PATCH] stage1: re-mkdir /proc instead of umount if it is a symlink
+
+In docker, the TARGET/proc will be a symlink to /proc.
+And if the docker instance is called with --privileged, it will umount
+the /proc of the whole instance in setup_proc.
+---
+ debian/changelog | 3 +++
+ functions        | 7 ++++++-
+ 2 files changed, 9 insertions(+), 1 deletion(-)
+
+diff --git a/functions b/functions
+index 1ac63f7..065320d 100644
+--- a/functions
++++ b/functions
+@@ -1183,7 +1183,12 @@ setup_proc () {
+ 		umount_on_exit /dev/shm
+ 		umount_on_exit /proc
+ 		umount_on_exit /proc/bus/usb
+-		umount "$TARGET/proc" 2>/dev/null || true
++		if [ -L "$TARGET/proc" ];then
++			rm -f $TARGET/proc
++			mkdir $TARGET/proc
++		else
++			umount "$TARGET/proc" 2>/dev/null || true
++		fi
+ 
+ 		# some container environment are used at second-stage, it already treats /proc and so on
+ 		if [ -z "$(ls -A "$TARGET/proc")" ]; then
+-- 
+GitLab
+