cachi2: use reflink if possible

use reflink to copy sources into build dir to save space

Signed-off-by: Martin Basti <mbasti@redhat.com>

atomic_reactor/plugins/cachi2_postprocess.py

@@ -9,11 +9,14 @@
 import json
 import os.path
 import shlex
+import shutil
 from dataclasses import dataclass
 from pathlib import Path
 from shutil import copytree
 from typing import Any, Optional, List, Dict
 
+import reflink
+
 from atomic_reactor.constants import (
     CACHITO_ENV_ARG_ALIAS,
     CACHITO_ENV_FILENAME,
@@ -24,7 +27,7 @@
     REMOTE_SOURCE_TARBALL_FILENAME,
     REMOTE_SOURCE_JSON_ENV_FILENAME,
 )
-from atomic_reactor.dirs import BuildDir
+from atomic_reactor.dirs import BuildDir, reflink_copy
 from atomic_reactor.plugin import Plugin
 
 from atomic_reactor.utils.cachi2 import generate_request_json
@@ -176,9 +179,18 @@ def inject_into_build_dir(
             created_dirs.append(dest_dir)
 
             # copy app and deps generated by cachito into build_dir
-            # TODO: reflink?
-            copytree(remote_source.sources_path/'app', dest_dir/'app', symlinks=True)
-            copytree(remote_source.sources_path/'deps', dest_dir/'deps', symlinks=True)
+            copy_method = shutil.copy2
+            if reflink.supported_at(dest_dir):
+                copy_method = reflink_copy
+            self.log.debug(
+                "copy method used for cachi2 build_dir_injecting: %s", copy_method.__name__)
+
+            copytree(
+                remote_source.sources_path/'app', dest_dir/'app',
+                symlinks=True, copy_function=copy_method)
+            copytree(
+                remote_source.sources_path/'deps', dest_dir/'deps',
+                symlinks=True, copy_function=copy_method)
 
             # Create cachito.env file with environment variables received from cachito request
             self.generate_cachito_env_file(dest_dir, remote_source.build_args)