exp save: add target arg

dvc/commands/experiments/save.py

@@ -1,6 +1,6 @@
 import argparse
 
-from dvc.cli import formatter
+from dvc.cli import completion, formatter
 from dvc.cli.command import CmdBase
 from dvc.cli.utils import append_doc_link
 from dvc.exceptions import DvcException
@@ -14,6 +14,7 @@ class CmdExperimentsSave(CmdBase):
     def run(self):
         try:
             ref = self.repo.experiments.save(
+                targets=self.args.targets,
                 name=self.args.name,
                 force=self.args.force,
                 include_untracked=self.args.include_untracked,
@@ -41,6 +42,18 @@ def add_parser(experiments_subparsers, parent_parser):
         help=EXPERIMENTS_SAVE_HELP,
         formatter_class=formatter.RawDescriptionHelpFormatter,
     )
+    save_parser.add_argument(
+        "targets",
+        nargs="*",
+        help="""\
+Stages to save. 'dvc.yaml' by default.
+The targets can be path to a dvc.yaml file or `.dvc` file,
+or a stage name from dvc.yaml file from
+current working directory. To save a stage from dvc.yaml
+from other directories, the target must be a path followed by colon `:`
+and then the stage name name.
+""",
+    ).complete = completion.DVCFILES_AND_STAGE
     save_parser.add_argument(
         "-f",
         "--force",

dvc/repo/experiments/executor/base.py

@@ -268,6 +268,7 @@ def _get_top_level_paths(cls, repo: "Repo") -> List["str"]:
     def save(
         cls,
         info: "ExecutorInfo",
+        targets: Optional[Iterable[str]] = None,
         force: bool = False,
         include_untracked: Optional[List[str]] = None,
         message: Optional[str] = None,
@@ -293,7 +294,12 @@ def save(
             include_untracked.append(LOCK_FILE)
 
         try:
-            stages = dvc.commit([], force=True, relink=False)
+            stages = []
+            if targets:
+                for target in targets:
+                    stages.append(dvc.commit(target, force=True, relink=False))
+            else:
+                stages = dvc.commit([], force=True, relink=False)
             exp_hash = cls.hash_exp(stages)
             if include_untracked:
                 dvc.scm.add(include_untracked, force=True)  # type: ignore[call-arg]

dvc/repo/experiments/save.py

@@ -1,5 +1,5 @@
 import os
-from typing import TYPE_CHECKING, List, Optional
+from typing import TYPE_CHECKING, Iterable, List, Optional
 
 from funcy import first
 
@@ -14,6 +14,7 @@
 
 def save(
     repo: "Repo",
+    targets: Optional[Iterable[str]] = None,
     name: Optional[str] = None,
     force: bool = False,
     include_untracked: Optional[List[str]] = None,
@@ -32,6 +33,7 @@ def save(
     try:
         save_result = executor.save(
             executor.info,
+            targets=targets,
             force=force,
             include_untracked=include_untracked,
             message=message,

tests/func/experiments/test_save.py

@@ -173,3 +173,19 @@ def test_exp_save_custom_message(tmp_dir, dvc, scm):
 
     exp = dvc.experiments.save(message="custom commit message")
     assert scm.gitpython.repo.commit(exp).message == "custom commit message"
+
+
+def test_exp_save_target(tmp_dir, dvc, scm):
+    setup_stage(tmp_dir, dvc, scm)
+    orig_dvclock = (tmp_dir / "dvc.lock").read_text()
+    (tmp_dir / "bar").write_text("modified")
+
+    tmp_dir.dvc_gen({"file": "orig"}, commit="add files")
+    orig_dvcfile = (tmp_dir / "file.dvc").read_text()
+    (tmp_dir / "file").write_text("modified")
+
+    dvc.experiments.save(["file"])
+    assert (tmp_dir / "bar").read_text() == "modified"
+    assert (tmp_dir / "dvc.lock").read_text() == orig_dvclock
+    assert (tmp_dir / "file").read_text() == "modified"
+    assert (tmp_dir / "file.dvc").read_text() != orig_dvcfile

tests/unit/command/test_experiments.py

@@ -475,7 +475,7 @@ def test_experiments_rename_invalid(dvc, scm, mocker, capsys, caplog):
 
 
 def test_experiments_save(dvc, scm, mocker):
-    cli_args = parse_args(["exp", "save", "--name", "exp-name", "--force"])
+    cli_args = parse_args(["exp", "save", "target", "--name", "exp-name", "--force"])
     assert cli_args.func == CmdExperimentsSave
 
     cmd = cli_args.func(cli_args)
@@ -484,7 +484,12 @@ def test_experiments_save(dvc, scm, mocker):
     assert cmd.run() == 0
 
     m.assert_called_once_with(
-        cmd.repo, name="exp-name", force=True, include_untracked=[], message=None
+        cmd.repo,
+        targets=["target"],
+        name="exp-name",
+        force=True,
+        include_untracked=[],
+        message=None,
     )
 
 
@@ -500,6 +505,7 @@ def test_experiments_save_message(dvc, scm, mocker, flag):
 
     m.assert_called_once_with(
         cmd.repo,
+        targets=[],
         name=None,
         force=False,
         include_untracked=[],