[Build]: Support to use symbol links for lazy installation targets to reduce the image size (#10923)

Why I did it
Support to use symbol links in platform folder to reduce the image size.
The current solution is to copy each lazy installation targets (xxx.deb files) to each of the folders in the platform folder. The size will keep growing when more and more packages added in the platform folder. For cisco-8000 as an example, the size will be up to 2G, while most of them are duplicate packages in the platform folder.

How I did it
Create a new folder in platform/common, all the deb packages are copied to the folder, any other folders where use the packages are the symbol links to the common folder.

Why platform.tar?
We have implemented a patch for it, see #10775, but the problem is the the onie use really old unzip version, cannot support the symbol links.
The current solution is similar to the PR 10775, but make the platform folder into a tar package, which can be supported by onie. During the installation, the package.tar will be extracted to the original folder and removed.

Author: xumia

build_debian.sh

@@ -647,5 +647,5 @@ fi
 pushd $FILESYSTEM_ROOT && sudo tar czf $OLDPWD/$FILESYSTEM_DOCKERFS -C ${DOCKERFS_PATH}var/lib/docker .; popd
 
 ## Compress together with /boot, /var/lib/docker and $PLATFORM_DIR as an installer payload zip file
-pushd $FILESYSTEM_ROOT && sudo zip $OLDPWD/$ONIE_INSTALLER_PAYLOAD -r boot/ $PLATFORM_DIR/; popd
+pushd $FILESYSTEM_ROOT && sudo tar czf platform.tar.gz -C $PLATFORM_DIR . && sudo zip -n .gz $OLDPWD/$ONIE_INSTALLER_PAYLOAD -r boot/ platform.tar.gz; popd
 sudo zip -g -n .squashfs:.gz $ONIE_INSTALLER_PAYLOAD $FILESYSTEM_SQUASHFS $FILESYSTEM_DOCKERFS

files/Aboot/boot0.j2

@@ -348,7 +348,12 @@ extract_image() {
 
     info "Extracting swi content"
     ## Unzip the image except boot0 and dockerfs archive
-    unzip -oq "$swipath" -x boot0 "$dockerfs" -d "$image_path"
+    unzip -oq "$swipath" -x boot0 "$dockerfs" "platform.tar.gz" -d "$image_path"
+
+    ## Extract the platform.tar.gz
+    info "Extracting platform.tar.gz"
+    mkdir -p "$image_path/platform"
+    unzip -oqp "$swipath" "platform.tar.gz" | tar xzf - -C "$image_path/platform" $TAR_EXTRA_OPTION
 
     ## detect rootfs type
     local mountstr="$(grep " $target_path " /proc/mounts)"

files/build_templates/sonic_debian_extension.j2

@@ -614,7 +614,9 @@ sudo LANG=C chroot $FILESYSTEM_ROOT depmod -a {{kversion}}
 sudo dpkg --root=$FILESYSTEM_ROOT -i {{deb}} || sudo LANG=C DEBIAN_FRONTEND=noninteractive chroot $FILESYSTEM_ROOT apt-get -y install -f --download-only
 
 sudo mkdir -p $FILESYSTEM_ROOT/$PLATFORM_DIR/{{dev}}
-sudo cp {{ deb }} $FILESYSTEM_ROOT/$PLATFORM_DIR/{{dev}}/
+sudo mkdir -p $FILESYSTEM_ROOT/$PLATFORM_DIR/common
+sudo cp {{ deb }} $FILESYSTEM_ROOT/$PLATFORM_DIR/common/
+sudo ln -sf "../common/{{ debfilename }}" "$FILESYSTEM_ROOT/$PLATFORM_DIR/{{dev}}/{{ debfilename }}"
 for f in $(find $FILESYSTEM_ROOT/var/cache/apt/archives -name "*.deb"); do
     sudo mv $f $FILESYSTEM_ROOT/$PLATFORM_DIR/{{dev}}/
 done

installer/arm64/install.sh

@@ -155,9 +155,9 @@ fi
 # Decompress the file for the file system directly to the partition
 if [ x"$docker_inram" = x"on" ]; then
     # when disk is small, keep dockerfs.tar.gz in disk, expand it into ramfs during initrd
-    unzip -o $ONIE_INSTALLER_PAYLOAD -d $demo_mnt/$image_dir
+    unzip -o $ONIE_INSTALLER_PAYLOAD -x "platform.tar.gz" -d $demo_mnt/$image_dir
 else
-    unzip -o $ONIE_INSTALLER_PAYLOAD -x "$FILESYSTEM_DOCKERFS" -d $demo_mnt/$image_dir
+    unzip -o $ONIE_INSTALLER_PAYLOAD -x "$FILESYSTEM_DOCKERFS" "platform.tar.gz" -d $demo_mnt/$image_dir
 
     if [ "$install_env" = "onie" ]; then
         TAR_EXTRA_OPTION="--numeric-owner"
@@ -168,6 +168,8 @@ else
     unzip -op $ONIE_INSTALLER_PAYLOAD "$FILESYSTEM_DOCKERFS" | tar xz $TAR_EXTRA_OPTION -f - -C $demo_mnt/$image_dir/$DOCKERFS_DIR
 fi
 
+mkdir -p $demo_mnt/$image_dir/platform
+unzip -op $ONIE_INSTALLER_PAYLOAD "platform.tar.gz" | tar xz $TAR_EXTRA_OPTION -f - -C $demo_mnt/$image_dir/platform
 
 if [ "$install_env" = "onie" ]; then
     # Store machine description in target file system

installer/armhf/install.sh

@@ -155,9 +155,9 @@ fi
 # Decompress the file for the file system directly to the partition
 if [ x"$docker_inram" = x"on" ]; then
     # when disk is small, keep dockerfs.tar.gz in disk, expand it into ramfs during initrd
-    unzip -o $ONIE_INSTALLER_PAYLOAD -d $demo_mnt/$image_dir
+    unzip -o $ONIE_INSTALLER_PAYLOAD -x "platform.tar.gz" -d $demo_mnt/$image_dir
 else
-    unzip -o $ONIE_INSTALLER_PAYLOAD -x "$FILESYSTEM_DOCKERFS" -d $demo_mnt/$image_dir
+    unzip -o $ONIE_INSTALLER_PAYLOAD -x "$FILESYSTEM_DOCKERFS" "platform.tar.gz" -d $demo_mnt/$image_dir
 
     if [ "$install_env" = "onie" ]; then
         TAR_EXTRA_OPTION="--numeric-owner"
@@ -168,6 +168,8 @@ else
     unzip -op $ONIE_INSTALLER_PAYLOAD "$FILESYSTEM_DOCKERFS" | tar xz $TAR_EXTRA_OPTION -f - -C $demo_mnt/$image_dir/$DOCKERFS_DIR
 fi
 
+mkdir -p $demo_mnt/$image_dir/platform
+unzip -op $ONIE_INSTALLER_PAYLOAD "platform.tar.gz" | tar xz $TAR_EXTRA_OPTION -f - -C $demo_mnt/$image_dir/platform
 
 if [ "$install_env" = "onie" ]; then
     # Store machine description in target file system

installer/x86_64/install.sh

@@ -536,9 +536,9 @@ fi
 # Decompress the file for the file system directly to the partition
 if [ x"$docker_inram" = x"on" ]; then
     # when disk is small, keep dockerfs.tar.gz in disk, expand it into ramfs during initrd
-    unzip -o $ONIE_INSTALLER_PAYLOAD -d $demo_mnt/$image_dir
+    unzip -o $ONIE_INSTALLER_PAYLOAD -x "platform.tar.gz" -d $demo_mnt/$image_dir
 else
-    unzip -o $ONIE_INSTALLER_PAYLOAD -x "$FILESYSTEM_DOCKERFS" -d $demo_mnt/$image_dir
+    unzip -o $ONIE_INSTALLER_PAYLOAD -x "$FILESYSTEM_DOCKERFS" "platform.tar.gz"  -d $demo_mnt/$image_dir
 
     if [ "$install_env" = "onie" ]; then
         TAR_EXTRA_OPTION="--numeric-owner"
@@ -549,6 +549,9 @@ else
     unzip -op $ONIE_INSTALLER_PAYLOAD "$FILESYSTEM_DOCKERFS" | tar xz $TAR_EXTRA_OPTION -f - -C $demo_mnt/$image_dir/$DOCKERFS_DIR
 fi
 
+mkdir -p $demo_mnt/$image_dir/platform
+unzip -op $ONIE_INSTALLER_PAYLOAD "platform.tar.gz" | tar xz $TAR_EXTRA_OPTION -f - -C $demo_mnt/$image_dir/platform
+
 if [ "$install_env" = "onie" ]; then
     # Store machine description in target file system
     if [ -f /etc/machine-build.conf ]; then