exp: Expose baseline and name via run_env.

Required by DVCLive for the experiments onboarding and live metrics features.

Related (not sure if closes): https://github.com/iterative/dvc/issues/6668

dvc/env.py

@@ -4,6 +4,8 @@ DVC_PAGER = "DVC_PAGER"
 DVC_ROOT = "DVC_ROOT"
 DVCLIVE_RESUME = "DVCLIVE_RESUME"
 DVC_IGNORE_ISATTY = "DVC_IGNORE_ISATTY"
+DVC_EXP_BASELINE_REV = "DVC_EXP_BASELINE_REV"
+DVC_EXP_NAME = "DVC_EXP_NAME"
 DVC_EXP_GIT_REMOTE = "DVC_EXP_GIT_REMOTE"
 DVC_EXP_AUTO_PUSH = "DVC_EXP_AUTO_PUSH"
 DVC_NO_ANALYTICS = "DVC_NO_ANALYTICS"

dvc/repo/experiments/queue/base.py

@@ -20,7 +20,7 @@ from typing import (
 from funcy import cached_property, retry
 
 from dvc.dependency import ParamsDependency
-from dvc.env import DVCLIVE_RESUME
+from dvc.env import DVC_EXP_BASELINE_REV, DVC_EXP_NAME, DVCLIVE_RESUME
 from dvc.exceptions import DvcException
 from dvc.lock import LockError
 from dvc.ui import ui
@@ -396,7 +396,13 @@ class BaseStashQueue(ABC):
                             )
 
                     # save additional repro command line arguments
-                    run_env = {DVCLIVE_RESUME: "1"} if resume_rev else {}
+                    run_env = {
+                        DVC_EXP_BASELINE_REV: baseline_rev,
+                    }
+                    if name:
+                        run_env[DVC_EXP_NAME] = name
+                    if resume_rev:
+                        run_env[DVCLIVE_RESUME] = "1"
                     self._pack_args(*args, run_env=run_env, **kwargs)
 
                     # save experiment as a stash commit

tests/func/experiments/test_experiments.py

@@ -2,6 +2,7 @@ import itertools
 import logging
 import os
 import stat
+from textwrap import dedent
 
 import pytest
 from funcy import first
@@ -682,3 +683,29 @@ def test_experiments_workspace_not_log_exception(caplog, dvc, scm):
             dvc.experiments.run()
 
     assert not caplog.text
+
+
+def test_run_env(tmp_dir, dvc, scm):
+    dump_run_env = dedent(
+        """\
+        import os
+        from dvc.env import DVC_EXP_BASELINE_REV, DVC_EXP_NAME
+        with open("DVC_EXP_BASELINE_REV", "w") as f:
+            f.write(os.environ.get(DVC_EXP_BASELINE_REV, ""))
+        with open("DVC_EXP_NAME", "w") as f:
+            f.write(os.environ.get(DVC_EXP_NAME, ""))
+        """
+    )
+    (tmp_dir / "dump_run_env.py").write_text(dump_run_env)
+    baseline = scm.get_rev()
+    dvc.stage.add(
+        cmd="python dump_run_env.py",
+        name="run_env",
+    )
+    dvc.experiments.run()
+    assert (tmp_dir / "DVC_EXP_BASELINE_REV").read_text().strip() == baseline
+    assert (tmp_dir / "DVC_EXP_NAME").read_text().strip() == ""
+
+    dvc.experiments.run(name="foo")
+    assert (tmp_dir / "DVC_EXP_BASELINE_REV").read_text().strip() == baseline
+    assert (tmp_dir / "DVC_EXP_NAME").read_text().strip() == "foo"