[aboot]: refactor boot0.j2 to support one image SONiC-to-SONiC upgrade

files/Aboot/boot0.j2

@@ -24,7 +24,7 @@ kernel_params=kernel-params
 
 aboot_machine="arista_unknown"
 
-target_path=/mnt/flash
+[ -z "$target_path" ] && target_path=/mnt/flash
 image_path="$target_path/image-%%IMAGE_VERSION%%"
 
 # expect the swi to be a non empty file
@@ -41,15 +41,18 @@ parse_environment_config() {
     done
 }
 
-extract_image() {
+clean_flash() {
     ## Remove all the other unnecssary files except swi file, boot-config
     for f in $(ls -A $target_path); do
         if [ $f != "${swipath##*/}" ] && [ $f != "boot-config" ]; then
             rm -rf "$target_path/$f"
         fi
     done
+}
+
+extract_image() {
 
-    mkdir "$image_path"
+    mkdir -p "$image_path"
 
     ## Unzip the image
     unzip -oq "$swipath" -x boot0 -d "$image_path"
@@ -58,10 +61,10 @@ extract_image() {
     rm -f $swipath
 
     ## detect rootfs type
-    rootfs_type=`grep /mnt/flash /proc/mounts | cut -d' ' -f3`
+    rootfs_type=`grep " $target_path " /proc/mounts | cut -d' ' -f3`
 
     ## vfat does not support symbol link
-    if [ $rootfs_type != "vfat" ]; then
+    if [ -n "$sonic_upgrade" ] || [ "$rootfs_type" != "vfat" ]; then
         mkdir -p "$image_path/{{ DOCKERFS_DIR }}"
 
         ## extract docker archive
@@ -70,15 +73,12 @@ extract_image() {
         ## clean up docker archive
         rm -f "$image_path/{{ FILESYSTEM_DOCKERFS }}"
     else
-        echo "/mnt/flash is $rootfs_type, extract {{ FILESYSTEM_DOCKERFS }} in later stage"
+        echo "$target_path is $rootfs_type, extract {{ FILESYSTEM_DOCKERFS }} in later stage"
     fi
 
     ## use new reduced-size boot swi
     echo "SWI=flash:image-%%IMAGE_VERSION%%/{{ ABOOT_BOOT_IMAGE }}" > "$target_path/boot-config"
 
-    ## remove original boot swi
-    rm -f "$swipath"
-
     ## sync disk operations
     sync
 }
@@ -120,6 +120,17 @@ platform_specific() {
     fi
 }
 
+# check the hash file in the image, and determine to install or just skip
+GIT_REVISION=$(unzip -p "$swipath" .imagehash)
+LOCAL_IMAGEHASH=$(cat $image_path/.imagehash 2>/dev/null || true)
+if [ "$GIT_REVISION" != "$LOCAL_IMAGEHASH" ]; then
+    [ -z "$sonic_upgrade" ] && clean_flash
+    extract_image
+fi
+
+[ -z "$sonic_upgrade" ] || exit 0
+
+# build the new cmdline
 echo "$append" >/tmp/append
 parse_environment_config >>/tmp/append
 cat /etc/cmdline | sed "/^\(${bootconfigvars// /\|}\|crashkernel\|loglevel\|ignore_loglevel\)\(\$\|=\)/d;/^\$/d" >>/tmp/append
@@ -129,6 +140,8 @@ echo "rw loop=image-%%IMAGE_VERSION%%/fs.squashfs loopfstype=squashfs apparmor=1
 # process platform specific operations
 platform_specific
 
+[ -e ${taget_path}/machine.conf ] || write_machine_config
+
 # use extra parameters from kernel-params hook if the file exists
 if [ -f "$image_path/$kernel_params" ]; then
     cat "$image_path/$kernel_params" >>/tmp/append
@@ -141,14 +154,6 @@ if ! grep -q "root=" /tmp/append; then
    echo "root=$rootdev" >>/tmp/append
 fi
 
-# check the hash file in the image, and determine to install or just skip
-GIT_REVISION=$(unzip -p "$swipath" .imagehash)
-LOCAL_IMAGEHASH=$(cat $image_path/.imagehash 2>/dev/null || true)
-if [ "$GIT_REVISION" != "$LOCAL_IMAGEHASH" ]; then
-    extract_image
-    write_machine_config
-fi
-
 # chainloading using kexec
 initrd_path="$image_path/$initrd"
 kernel_path="$image_path/$kernel"