Feat:support subpath in juicefs volume dynamic-mount (#4241)

Signed-off-by: jiuyu <guotongyu.gty@alibaba-inc.com>
Co-authored-by: jiuyu <guotongyu.gty@alibaba-inc.com>

addons/dynamic-mount/juicefs/docker/mount.sh

@@ -7,17 +7,37 @@ if [[ $# -ne 4 ]]; then
     exit 1
 fi
 
-mount_src=$1        # e.g. juicefs://mybucket
+mount_src=$1        # e.g. juicefs://volume-name/subpath
 mount_target=$2     # e.g. /runtime-mnt/thin/default/thin-demo/thin-fuse/mybucket
 fs_type=$3
 mount_opt_file=$4   # e.g. /etc/fluid/mount-opts/mybucket.opts (mount options in json format)
 
-filesystem_name=${mount_src#juicefs://}
+# Check if the mount_src starts with juicefs://
+if [[ "$mount_src" == juicefs://* ]]; then
+    juicefs_volume_path=${mount_src#juicefs://}
+else
+    echo "Error: mount_src does not start with juicefs://"
+    exit 1
+fi
+
+if [[ "$juicefs_volume_path" == *"/"* ]]; then
+    volume_name="${juicefs_volume_path%%/*}"
+    volume_subpath="${juicefs_volume_path#*/}"
+else
+    volume_name=$juicefs_volume_path
+fi
+
 token_file=$(cat ${mount_opt_file} | jq -r '.["token"]')
 access_key_file=$(cat ${mount_opt_file} | jq -r '.["access-key"]')
 secret_key_file=$(cat ${mount_opt_file} | jq -r '.["secret-key"]')
 bucket=$(cat ${mount_opt_file} | jq -r '.["bucket"]')
 
-juicefs auth $filesystem_name --token `cat $token_file` --access-key `cat $access_key_file` --secret-key `cat $secret_key_file` --bucket "$bucket"
+juicefs auth $volume_name --token `cat $token_file` --access-key `cat $access_key_file` --secret-key `cat $secret_key_file` --bucket "$bucket"
 
-exec juicefs mount -f $filesystem_name $mount_target
+if [[ -z "$volume_subpath" ]]; then
+# e.g. juicefs://volume-name/ || juicefs://volume-name
+    exec juicefs mount -f $volume_name $mount_target
+else
+# e.g. juicefs://volume-name/subpath-1 || juicefs://volume-name/subpath-1/subpath-2/.../
+    exec juicefs mount -f $volume_name $mount_target --subdir="/"$volume_subpath
+fi