dvc: Decouple dvc_api_available from get_dvc_repo.

Closes #473

src/dvclive/dvc.py

@@ -73,14 +73,19 @@ def make_checkpoint():
         sleep(_CHECKPOINT_SLEEP)
 
 
-def get_dvc_repo():
+def dvc_api_available() -> bool:
     # noqa pylint: disable=unused-import
     try:
-        from dvc.exceptions import NotDvcRepoError
-        from dvc.repo import Repo
-        from dvc.scm import SCMError
+        import dvc  # noqa: F401
     except ImportError:
-        return None
+        return False
+    return True
+
+
+def get_dvc_repo():
+    from dvc.exceptions import NotDvcRepoError
+    from dvc.repo import Repo
+    from dvc.scm import SCMError
 
     try:
         return Repo()

src/dvclive/live.py

@@ -5,10 +5,13 @@
 from pathlib import Path
 from typing import Any, Dict, List, Optional, Set, Union
 
+from dvc_studio_client.env import STUDIO_TOKEN
+from dvc_studio_client.post_live_metrics import post_live_metrics
 from ruamel.yaml.representer import RepresenterError
 
 from . import env
 from .dvc import (
+    dvc_api_available,
     get_dvc_repo,
     get_random_exp_name,
     make_checkpoint,
@@ -29,13 +32,6 @@
     open_file_in_browser,
 )
 
-try:
-    from dvc_studio_client.env import STUDIO_TOKEN
-    from dvc_studio_client.post_live_metrics import post_live_metrics
-except ImportError:
-    post_live_metrics = None
-    STUDIO_TOKEN = None
-
 logging.basicConfig()
 logger = logging.getLogger("dvclive")
 logger.setLevel(os.getenv(env.DVCLIVE_LOGLEVEL, "INFO").upper())
@@ -110,11 +106,6 @@ def _init_cleanup(self):
                 os.remove(f)
 
     def _init_dvc(self):
-        self._dvc_repo = get_dvc_repo()
-
-        if self._dvc_repo is not None:
-            self._baseline_rev = self._dvc_repo.scm.get_rev()
-
         if os.getenv(env.DVC_EXP_BASELINE_REV, None):
             # `dvc exp` execution
             self._baseline_rev = os.getenv(env.DVC_EXP_BASELINE_REV, "")
@@ -124,50 +115,56 @@ def _init_dvc(self):
                 logger.warning(
                     "Ignoring `_save_dvc_exp` because `dvc exp run` is running"
                 )
-        elif self._save_dvc_exp:
-            if self._dvc_repo is not None:
-                # `DVCLive Only` or `dvc repro` execution
-                self._exp_name = get_random_exp_name(
-                    self._dvc_repo.scm, self._baseline_rev
-                )
-                mark_dvclive_only_started()
-            else:
+                self._save_dvc_exp = False
+            return
+
+        self._dvc_repo = get_dvc_repo()
+        if self._dvc_repo is None:
+            if self._save_dvc_exp:
+                if not dvc_api_available():
+                    logger.warning(
+                        "Can't save experiment without the DVC Python API."
+                        "\nYou can install it by calling `pip install dvc`."
+                    )
                 logger.warning(
                     "Can't save experiment without a DVC Repo."
                     "\nYou can create a DVC Repo by calling `dvc init`."
                 )
+                self._save_dvc_exp = False
+            return
 
-    def _init_studio(self):
-        if post_live_metrics is not None:
-            if not os.getenv(STUDIO_TOKEN, None):
-                logger.debug("Skipping `studio` report.")
-                self._studio_events_to_skip.add("start")
-                self._studio_events_to_skip.add("data")
-                self._studio_events_to_skip.add("done")
-                return
+        self._baseline_rev = self._dvc_repo.scm.get_rev()
+        if self._save_dvc_exp:
+            self._exp_name = get_random_exp_name(self._dvc_repo.scm, self._baseline_rev)
+            mark_dvclive_only_started()
 
-        if not (self._dvc_repo or self._inside_dvc_exp):
-            logger.debug("`studio` report can't be used without a DVC Repo.")
+    def _init_studio(self):
+        if not os.getenv(STUDIO_TOKEN, None):
+            logger.debug("Missing env var `STUDIO_TOKEN`, skipping `studio` report.")
             self._studio_events_to_skip.add("start")
             self._studio_events_to_skip.add("data")
             self._studio_events_to_skip.add("done")
-            return
-
-        if self._inside_dvc_exp:
+        elif self._inside_dvc_exp:
             logger.debug("Skipping `studio` report `start` and `done` events.")
             self._studio_events_to_skip.add("start")
             self._studio_events_to_skip.add("done")
-        else:
-            response = False
-            if post_live_metrics is not None:
-                response = post_live_metrics(
-                    "start", self._baseline_rev, self._exp_name, "dvclive"
-                )
-            else:
-                logger.debug(
-                    "`dvc_studio_client` is not installed.\n"
-                    "You can install it with `pip install dvc-studio-client`."
+        elif self._dvc_repo is None:
+            if not dvc_api_available():
+                logger.warning(
+                    "Can't send updates to Studio without the DVC Python API."
+                    "\nYou can install it by calling `pip install dvc`."
                 )
+            logger.warning(
+                "Can't send updates to Studio without a DVC Repo."
+                "\nYou can create a DVC Repo by calling `dvc init`."
+            )
+            self._studio_events_to_skip.add("start")
+            self._studio_events_to_skip.add("data")
+            self._studio_events_to_skip.add("done")
+        else:
+            response = post_live_metrics(
+                "start", self._baseline_rev, self._exp_name, "dvclive"
+            )
             if not response:
                 logger.debug(
                     "`studio` report `start` event failed. "
@@ -384,15 +381,10 @@ def end(self):
                 logger.warning("`post_to_studio` `done` event failed.")
             self._studio_events_to_skip.add("done")
             self._studio_events_to_skip.add("data")
-
         else:
             self.make_report()
 
-        if (
-            self._dvc_repo is not None
-            and not self._inside_dvc_exp
-            and self._save_dvc_exp
-        ):
+        if self._save_dvc_exp:
             from dvc.exceptions import DvcException
 
             try:

tests/test_dvc.py

@@ -197,3 +197,9 @@ def test_exp_save_dvcexception_is_ignored(tmp_dir, mocker):
 
     with Live(save_dvc_exp=True):
         pass
+
+
+def test_exp_save_skipped_if_not_dvc_api_available(tmp_dir, mocker):
+    mocker.patch("dvclive.live.dvc_api_available", return_value=False)
+    live = Live(save_dvc_exp=True)
+    assert not live._save_dvc_exp