From 223c66f8b048cf8fc49655979b58b1b3694f445a Mon Sep 17 00:00:00 2001
From: Harrison Cook <harrison.cook@ecmwf.int>
Date: Tue, 29 Oct 2024 09:11:40 +0000
Subject: [PATCH] Initial commit to provide failover - Wraps experiment to
 capture connection errors - Logs to disk if server not found

---
 .../training/diagnostics/mlflow/logger.py     | 74 ++++++++++++++++++-
 1 file changed, 72 insertions(+), 2 deletions(-)

diff --git a/src/anemoi/training/diagnostics/mlflow/logger.py b/src/anemoi/training/diagnostics/mlflow/logger.py
index 183e7a0d..f153ff9e 100644
--- a/src/anemoi/training/diagnostics/mlflow/logger.py
+++ b/src/anemoi/training/diagnostics/mlflow/logger.py
@@ -10,6 +10,7 @@
 
 from __future__ import annotations
 
+import functools
 import io
 import logging
 import os
@@ -23,7 +24,10 @@
 from typing import Literal
 from weakref import WeakValueDictionary
 
+import mlflow
+from mlflow import MlflowClient
 from packaging.version import Version
+from pytorch_lightning.loggers.mlflow import LOCAL_FILE_URI_PREFIX
 from pytorch_lightning.loggers.mlflow import MLFlowLogger
 from pytorch_lightning.loggers.mlflow import _convert_params
 from pytorch_lightning.loggers.mlflow import _flatten_dict
@@ -36,7 +40,6 @@
 if TYPE_CHECKING:
     from argparse import Namespace
 
-    import mlflow
 
 LOGGER = logging.getLogger(__name__)
 
@@ -244,6 +247,8 @@ def _remove_csi(line: bytes) -> bytes:
 class AnemoiMLflowLogger(MLFlowLogger):
     """A custom MLflow logger that logs terminal output."""
 
+    _failed_to_offline = False
+
     def __init__(
         self,
         experiment_name: str = "lightning_logs",
@@ -323,6 +328,7 @@ def __init__(
             tracking_uri=tracking_uri,
             on_resume_create_child=on_resume_create_child,
         )
+        self._save_dir = f"{LOCAL_FILE_URI_PREFIX}{save_dir}"
         # Before creating the run we need to overwrite the tracking_uri and save_dir if offline
         if offline:
             # OFFLINE - When we run offline we can pass a save_dir pointing to a local path
@@ -426,7 +432,71 @@ def _get_mlflow_run_params(
     def experiment(self) -> MLFlowLogger.experiment:
         if rank_zero_only.rank == 0:
             self.auth.authenticate()
-        return super().experiment
+
+        parent_obj = super()
+        logger_obj = self
+        experiment = super().experiment
+
+        if self._failed_to_offline:
+            self.return_to_online()
+
+        class WrappedExperiment:
+            """Wrap the experiment object to handle connection errors.
+
+            Fails over to offline logging if an error occurs.
+            """
+
+            def __getattr__(self, key: str) -> Any:
+                # Only wrap logging calls
+                if not hasattr(experiment, key) or not key.startswith("log"):
+                    return super().__getattr__(key)
+                if not callable(getattr(experiment, key)):
+                    return getattr(experiment, key)
+
+                @functools.wraps(getattr(experiment, key))
+                def wrapped_method(*args, **kwargs) -> Any:
+                    try:
+                        return getattr(experiment, key)(*args, **kwargs)
+                    except mlflow.MlflowException as e:
+                        LOGGER.warning("An error occurred when calling %s: %s", key, e)
+                        logger_obj.failover_to_offline()
+                        global experiment
+                        experiment = parent_obj.experiment
+                    return getattr(experiment, key)(*args, **kwargs)
+
+                return wrapped_method
+
+        return WrappedExperiment
+
+    def failover_to_offline(self) -> None:
+        """Failover to offline mode."""
+        self._initialized = False
+        self._mlflow_client = MlflowClient(tracking_uri=self._save_dir)
+        self._failed_to_offline = True
+
+    def return_to_online(self) -> None:
+        """Return to online mode."""
+        try:
+            health_check(self._tracking_uri)
+        except ConnectionError:
+            return
+
+        self._initialized = False
+        self._mlflow_client = MlflowClient(tracking_uri=self._tracking_uri)
+        self._failed_to_offline = False
+
+        from anemoi.training.utils.mlflow_sync import MlFlowSync
+
+        try:
+            MlFlowSync(
+                self._save_dir,
+                self._tracking_uri,
+                self._run_id,
+                self._experiment_name,
+            ).sync()
+        except Exception as e:  # noqa: BLE001
+            LOGGER.warning("Failed to sync to online server: %s", e)
+            self.failover_to_offline()
 
     @rank_zero_only
     def log_system_metrics(self) -> None: