experiments: enable by default, support no_scm (#5019)

* experiments: enable by default, support no_scm

* mark experiments option obsolete

dvc/command/experiments.py

@@ -300,9 +300,6 @@ class CmdExperimentsShow(CmdBase):
 
         from dvc.utils.pager import pager
 
-        if not self.repo.experiments:
-            return 0
-
         try:
             all_experiments = self.repo.experiments.show(
                 all_branches=self.args.all_branches,
@@ -355,8 +352,6 @@ class CmdExperimentsShow(CmdBase):
 
 class CmdExperimentsApply(CmdBase):
     def run(self):
-        if not self.repo.experiments:
-            return 0
 
         self.repo.experiments.apply(self.args.experiment)
 
@@ -402,8 +397,6 @@ def _show_diff(
 
 class CmdExperimentsDiff(CmdBase):
     def run(self):
-        if not self.repo.experiments:
-            return 0
 
         try:
             diff = self.repo.experiments.diff(
@@ -445,8 +438,6 @@ class CmdExperimentsDiff(CmdBase):
 
 class CmdExperimentsRun(CmdRepro):
     def run(self):
-        if not self.repo.experiments:
-            return 0
 
         saved_dir = os.path.realpath(os.curdir)
         os.chdir(self.args.cwd)
@@ -483,9 +474,6 @@ class CmdExperimentsGC(CmdRepro):
     def run(self):
         from dvc.repo.gc import _raise_error_if_all_disabled
 
-        if not self.repo.experiments:
-            return 0
-
         _raise_error_if_all_disabled(
             all_branches=self.args.all_branches,
             all_tags=self.args.all_tags,
@@ -536,8 +524,6 @@ class CmdExperimentsGC(CmdRepro):
 
 class CmdExperimentsBranch(CmdBase):
     def run(self):
-        if not self.repo.experiments:
-            return 0
 
         self.repo.experiments.branch(self.args.experiment, self.args.branch)
 
@@ -545,7 +531,7 @@ class CmdExperimentsBranch(CmdBase):
 
 
 def add_parser(subparsers, parent_parser):
-    EXPERIMENTS_HELP = "Commands to display and compare experiments."
+    EXPERIMENTS_HELP = "Commands to run and compare experiments."
 
     experiments_parser = subparsers.add_parser(
         "experiments",
@@ -553,6 +539,7 @@ def add_parser(subparsers, parent_parser):
         aliases=["exp"],
         description=append_doc_link(EXPERIMENTS_HELP, "experiments"),
         formatter_class=argparse.RawDescriptionHelpFormatter,
+        help=EXPERIMENTS_HELP,
     )
 
     experiments_subparsers = experiments_parser.add_subparsers(

dvc/config.py

@@ -141,7 +141,7 @@ SCHEMA = {
         Optional("hardlink_lock", default=False): Bool,
         Optional("no_scm", default=False): Bool,
         Optional("autostage", default=False): Bool,
-        Optional("experiments", default=False): Bool,
+        Optional("experiments"): Bool,  # obsoleted
         Optional("check_update", default=True): Bool,
     },
     "cache": {

dvc/repo/__init__.py

@@ -133,7 +133,6 @@ class Repo:
         from dvc.cache import Cache
         from dvc.data_cloud import DataCloud
         from dvc.lock import LockNoop, make_lock
-        from dvc.repo.experiments import Experiments
         from dvc.repo.metrics import Metrics
         from dvc.repo.params import Params
         from dvc.repo.plots import Plots
@@ -179,11 +178,6 @@ class Repo:
             self.state = State(self)
             self.stage_cache = StageCache(self)
 
-            try:
-                self.experiments = Experiments(self)
-            except NotImplementedError:
-                self.experiments = None
-
             self._ignore()
 
         self.metrics = Metrics(self)
@@ -198,6 +192,12 @@ class Repo:
         no_scm = self.config["core"].get("no_scm", False)
         return self._scm if self._scm else SCM(self.root_dir, no_scm=no_scm)
 
+    @cached_property
+    def experiments(self):
+        from dvc.repo.experiments import Experiments
+
+        return Experiments(self)
+
     @property
     def tree(self) -> "BaseTree":
         return self._tree
@@ -258,8 +258,6 @@ class Repo:
             self.config.files["local"],
             self.tmp_dir,
         ]
-        if self.experiments:
-            flist.append(self.experiments.exp_dir)
 
         if path_isin(self.cache.local.cache_dir, self.root_dir):
             flist += [self.cache.local.cache_dir]

dvc/repo/experiments/__init__.py

@@ -28,7 +28,7 @@ from dvc.repo.experiments.base import (
 )
 from dvc.repo.experiments.executor import BaseExecutor, LocalExecutor
 from dvc.stage.run import CheckpointKilledError
-from dvc.utils import env2bool, relpath
+from dvc.utils import relpath
 
 logger = logging.getLogger(__name__)
 
@@ -72,7 +72,6 @@ class Experiments:
         repo (dvc.repo.Repo): repo instance that these experiments belong to.
     """
 
-    EXPERIMENTS_DIR = "experiments"
     STASH_EXPERIMENT_FORMAT = "dvc-exp:{rev}:{baseline_rev}:{name}"
     STASH_EXPERIMENT_RE = re.compile(
         r"(?:commit: )"
@@ -92,12 +91,10 @@ class Experiments:
 
     def __init__(self, repo):
         from dvc.lock import make_lock
+        from dvc.scm.base import NoSCMError
 
-        if not (
-            env2bool("DVC_TEST")
-            or repo.config["core"].get("experiments", False)
-        ):
-            raise NotImplementedError
+        if repo.config["core"].get("no_scm", False):
+            raise NoSCMError
 
         self.repo = repo
         self.scm_lock = make_lock(
@@ -105,10 +102,6 @@ class Experiments:
             tmp_dir=self.repo.tmp_dir,
         )
 
-    @cached_property
-    def exp_dir(self):
-        return os.path.join(self.repo.dvc_dir, self.EXPERIMENTS_DIR)
-
     @property
     def scm(self):
         return self.repo.scm
@@ -117,23 +110,13 @@ class Experiments:
     def dvc_dir(self):
         return relpath(self.repo.dvc_dir, self.repo.scm.root_dir)
 
-    @cached_property
-    def exp_dvc_dir(self):
-        return os.path.join(self.exp_dir, self.dvc_dir)
-
-    @property
-    def exp_dvc(self):
-        return self.repo
-
     @contextmanager
     def chdir(self):
         yield
 
     @cached_property
     def args_file(self):
-        return os.path.join(
-            self.exp_dvc.tmp_dir, BaseExecutor.PACKED_ARGS_FILE
-        )
+        return os.path.join(self.repo.tmp_dir, BaseExecutor.PACKED_ARGS_FILE)
 
     @cached_property
     def stash(self):
@@ -256,10 +239,10 @@ class Experiments:
         logger.debug("Using experiment params '%s'", params)
 
         for params_fname in params:
-            path = PathInfo(self.exp_dvc.root_dir) / params_fname
+            path = PathInfo(self.repo.root_dir) / params_fname
             suffix = path.suffix.lower()
             modify_data = MODIFIERS[suffix]
-            with modify_data(path, tree=self.exp_dvc.tree) as data:
+            with modify_data(path, tree=self.repo.tree) as data:
                 benedict(data).merge(params[params_fname], overwrite=True)
 
         # Force params file changes to be staged in git

dvc/repo/plots/diff.py

@@ -12,12 +12,6 @@ def _revisions(repo, revs, experiment):
 
 
 def diff(repo, *args, revs=None, experiment=False, **kwargs):
-    if experiment:
-        # use experiments repo brancher with templates from the main repo
-        kwargs["templates"] = repo.plots.templates
-        plots_repo = repo.experiments.exp_dvc
-    else:
-        plots_repo = repo
-    return plots_repo.plots.show(
+    return repo.plots.show(
         *args, revs=_revisions(repo, revs, experiment), **kwargs
     )

tests/func/experiments/test_experiments.py

@@ -305,3 +305,28 @@ def test_branch(tmp_dir, scm, dvc, exp_stage):
 
     assert "branch-ref-b" in scm.list_branches()
     assert scm.resolve_rev("branch-ref-b") == exp_b
+
+
+def test_no_scm(tmp_dir):
+    from dvc.repo import Repo as DvcRepo
+    from dvc.scm.base import NoSCMError
+
+    dvc = DvcRepo.init(no_scm=True)
+
+    with pytest.raises(NoSCMError):
+        dvc.experiments.run()
+
+    with pytest.raises(NoSCMError):
+        dvc.experiments.apply()
+
+    with pytest.raises(NoSCMError):
+        dvc.experiments.branch()
+
+    with pytest.raises(NoSCMError):
+        dvc.experiments.diff()
+
+    with pytest.raises(NoSCMError):
+        dvc.experiments.show()
+
+    with pytest.raises(NoSCMError):
+        dvc.experiments.gc()

tests/unit/command/test_experiments.py

@@ -15,7 +15,7 @@ from dvc.exceptions import InvalidArgumentError
 from .test_repro import default_arguments as repro_arguments
 
 
-def test_experiments_apply(dvc, mocker):
+def test_experiments_apply(dvc, scm, mocker):
     cli_args = parse_args(["experiments", "apply", "exp_rev"])
     assert cli_args.func == CmdExperimentsApply
 
@@ -27,7 +27,7 @@ def test_experiments_apply(dvc, mocker):
     m.assert_called_once_with(cmd.repo, "exp_rev")
 
 
-def test_experiments_diff(dvc, mocker):
+def test_experiments_diff(dvc, scm, mocker):
     cli_args = parse_args(
         [
             "experiments",
@@ -54,7 +54,7 @@ def test_experiments_diff(dvc, mocker):
     )
 
 
-def test_experiments_show(dvc, mocker):
+def test_experiments_show(dvc, scm, mocker):
     cli_args = parse_args(
         [
             "experiments",
@@ -84,7 +84,7 @@ def test_experiments_show(dvc, mocker):
 @pytest.mark.parametrize(
     "args, resume", [(["exp", "run"], None), (["exp", "resume"], ":last")]
 )
-def test_experiments_run(dvc, mocker, args, resume):
+def test_experiments_run(dvc, scm, mocker, args, resume):
     default_arguments = {
         "params": [],
         "name": None,
@@ -105,7 +105,7 @@ def test_experiments_run(dvc, mocker, args, resume):
     )
 
 
-def test_experiments_gc(dvc, mocker):
+def test_experiments_gc(dvc, scm, mocker):
     cli_args = parse_args(
         [
             "exp",
@@ -140,7 +140,7 @@ def test_experiments_gc(dvc, mocker):
         cmd.run()
 
 
-def test_experiments_branch(dvc, mocker):
+def test_experiments_branch(dvc, scm, mocker):
     cli_args = parse_args(["experiments", "branch", "expname", "branchname"])
     assert cli_args.func == CmdExperimentsBranch