feat: blobless clone

test/import_blobless.txt

@@ -0,0 +1,53 @@
+......
+=== ./immutable/hash (git) ===
+Cloning into '.'...
+warning: filtering not recognized by server, ignoring
+Note: switching to '5b3504594f7354121cf024dc734bf79e270cffd3'.
+
+You are in 'detached HEAD' state. You can look around, make experimental
+changes and commit them, and you can discard any commits you make in this
+state without impacting any branches by switching back to a branch.
+
+If you want to create a new branch to retain commits you create, you may
+do so (now or later) by using -c with the switch command. Example:
+
+  git switch -c <new-branch-name>
+
+Or undo this operation with:
+
+  git switch -
+
+Turn off this advice by setting config variable advice.detachedHead to false
+
+HEAD is now at 5b35045... update changelog
+=== ./immutable/hash_tar (tar) ===
+Downloaded tarball from 'file:///vcstmp/archive.tar.gz' and unpacked it
+=== ./immutable/hash_zip (zip) ===
+Downloaded zipfile from 'file:///vcstmp/archive.zip' and unpacked it
+=== ./immutable/tag (git) ===
+Cloning into '.'...
+warning: filtering not recognized by server, ignoring
+Note: switching to 'tags/0.1.27'.
+
+You are in 'detached HEAD' state. You can look around, make experimental
+changes and commit them, and you can discard any commits you make in this
+state without impacting any branches by switching back to a branch.
+
+If you want to create a new branch to retain commits you create, you may
+do so (now or later) by using -c with the switch command. Example:
+
+  git switch -c <new-branch-name>
+
+Or undo this operation with:
+
+  git switch -
+
+Turn off this advice by setting config variable advice.detachedHead to false
+
+HEAD is now at 8087b72... 0.1.27
+=== ./vcs2l (git) ===
+Cloning into '.'...
+warning: filtering not recognized by server, ignoring
+=== ./without_version (git) ===
+Cloning into '.'...
+warning: filtering not recognized by server, ignoring

test/test_commands.py

@@ -270,6 +270,45 @@ def test_import_shallow(self):
         finally:
             rmtree(workdir)
 
+    def test_import_blobless(self):
+        workdir = os.path.join(TEST_WORKSPACE, 'import-blobless')
+        os.makedirs(workdir)
+        try:
+            output = run_command(
+                'import',
+                ['--blobless-clone', '--input', self.repos_file_path, '.'],
+                subfolder='import-blobless',
+            )
+            # the actual output contains absolute paths
+            output = output.replace(
+                b'repository in ' + workdir.encode() + b'/', b'repository in ./'
+            )
+            expected = get_expected_output('import_blobless')
+            # newer git versions don't append ... after the commit hash
+            assert output == expected or output == expected.replace(b'... ', b' ')
+
+            git_repos = [
+                os.path.join(workdir, 'immutable', 'hash'),
+                os.path.join(workdir, 'immutable', 'tag'),
+                os.path.join(workdir, 'vcs2l'),
+                os.path.join(workdir, 'without_version'),
+            ]
+            for repo_path in git_repos:
+                partial_filter = subprocess.check_output(
+                    ['git', 'config', '--get', 'remote.origin.partialclonefilter'],
+                    stderr=subprocess.STDOUT,
+                    cwd=repo_path,
+                ).strip()
+                self.assertEqual(partial_filter, b'blob:none')
+                promisor = subprocess.check_output(
+                    ['git', 'config', '--get', 'remote.origin.promisor'],
+                    stderr=subprocess.STDOUT,
+                    cwd=repo_path,
+                ).strip()
+                self.assertEqual(promisor, b'true')
+        finally:
+            rmtree(workdir)
+
     def test_import_url(self):
         workdir = os.path.join(TEST_WORKSPACE, 'import-url')
         os.makedirs(workdir)

vcs2l/clients/git.py

@@ -326,6 +326,8 @@ def import_(self, command):
 
             # fetch updates for existing repo
             cmd_fetch = [GitClient._executable, 'fetch', remote]
+            if command.blobless_clone:
+                cmd_fetch.append('--filter=blob:none')
             if command.shallow:
                 result_version_type, version_name = self._check_version_type(
                     command.url, checkout_version, command.retry
@@ -409,7 +411,17 @@ def import_(self, command):
 
             if not command.shallow or version_type in (None, 'branch'):
                 cmd_clone = [GitClient._executable, 'clone', command.url, '.']
-                if version_type == 'branch':
+                if command.blobless_clone:
+                    cmd_clone += ['--filter=blob:none']
+                    if version_type == 'branch':
+                        cmd_clone += ['-b', version_name]
+                        checkout_version = None
+                    elif command.version:
+                        cmd_clone.append('--no-checkout')
+                        checkout_version = command.version
+                    else:
+                        checkout_version = None
+                elif version_type == 'branch':
                     cmd_clone += ['-b', version_name]
                     checkout_version = None
                 else:

vcs2l/commands/import_.py

@@ -19,7 +19,15 @@ class ImportCommand(Command):
     command = 'import'
     help = 'Import the list of repositories'
 
-    def __init__(self, args, url, version=None, recursive=False, shallow=False):
+    def __init__(
+        self,
+        args,
+        url,
+        version=None,
+        recursive=False,
+        shallow=False,
+        blobless_clone=False,
+    ):
         super(ImportCommand, self).__init__(args)
         self.url = url
         self.version = version
@@ -28,6 +36,7 @@ def __init__(self, args, url, version=None, recursive=False, shallow=False):
         self.skip_existing = args.skip_existing
         self.recursive = recursive
         self.shallow = shallow
+        self.blobless_clone = blobless_clone
 
 
 def get_parser():
@@ -49,12 +58,19 @@ def get_parser():
         help="Delete existing directories if they don't contain the "
         'repository being imported',
     )
-    group.add_argument(
+    clone_type_group = group.add_mutually_exclusive_group()
+    clone_type_group.add_argument(
         '--shallow',
         action='store_true',
         default=False,
         help='Create a shallow clone without a history',
     )
+    clone_type_group.add_argument(
+        '--blobless-clone',
+        action='store_true',
+        default=False,
+        help='Only clone the commit history first, then checkout to the target version to obtain files',
+    )
     group.add_argument(
         '--recursive',
         action='store_true',
@@ -207,6 +223,7 @@ def generate_jobs(repos, args):
             str(repo['version']) if 'version' in repo else None,
             recursive=args.recursive,
             shallow=args.shallow,
+            blobless_clone=args.blobless_clone,
         )
         job = {'client': client, 'command': command}
         jobs.append(job)
@@ -247,6 +264,7 @@ def main(args=None, stdout=None, stderr=None):
     except (RuntimeError, request.URLError) as e:
         print(ansi('redf') + str(e) + ansi('reset'), file=sys.stderr)
         return 1
+
     jobs = generate_jobs(repos, args)
     add_dependencies(jobs)