diff --git a/.github/workflows/unittest.yaml b/.github/workflows/unittest.yaml
index 41f7e226ab..a26174b863 100644
--- a/.github/workflows/unittest.yaml
+++ b/.github/workflows/unittest.yaml
@@ -31,8 +31,17 @@ jobs:
     - name: Check ray status
       working-directory: trinity-${{ github.run_id }}/.github/workflows/docker
       run: |
-        docker compose exec trinity-node-1 ray status
-        docker compose exec trinity-node-2 ray status
+        MAX_RETRIES=20
+        RETRY_INTERVAL=5
+        for i in $(seq 1 $MAX_RETRIES); do
+          docker compose exec trinity-node-1 ray status && docker compose exec trinity-node-2 ray status && break
+          echo "Waiting for ray cluster to be ready... ($i/$MAX_RETRIES)"
+          sleep $RETRY_INTERVAL
+          if [ "$i" -eq "$MAX_RETRIES" ]; then
+            echo "Ray cluster failed to start after $MAX_RETRIES retries."
+            exit 1
+          fi
+        done
 
     - name: Decide test type
       id: test_type
@@ -89,7 +98,7 @@ jobs:
         fi
 
     - name: Upload test results
-      if: env.tests_run == 'true'
+      if: env.tests_run == 'true' || failure()
       uses: actions/upload-artifact@v4
       with:
         name: pytest-results
@@ -97,7 +106,7 @@ jobs:
       continue-on-error: true
 
     - name: Publish Test Report
-      if: env.tests_run == 'true'
+      if: env.tests_run == 'true' || failure()
       uses: ctrf-io/github-test-reporter@v1
       with:
         report-path: trinity-${{ github.run_id }}/report.json
diff --git a/tests/common/config_test.py b/tests/common/config_test.py
index 994b573c04..a7b4d63530 100644
--- a/tests/common/config_test.py
+++ b/tests/common/config_test.py
@@ -74,6 +74,14 @@ def test_continue_from_checkpoint_is_valid(self):
         timestamp = config.name.split("_")[-1]
         self.assertTrue(datetime.datetime.strptime(timestamp, "%Y%m%d%H%M%S"))
 
+    def test_config_flatten(self):
+        config = get_template_config()
+        flat_config = config.flatten()
+        self.assertIsInstance(flat_config, dict)
+        for key, value in flat_config.items():
+            self.assertIsInstance(key, str)
+            self.assertNotIsInstance(value, dict)
+
     def tearDown(self):
         if os.path.exists(CHECKPOINT_ROOT_DIR):
             shutil.rmtree(CHECKPOINT_ROOT_DIR)
diff --git a/trinity/common/config.py b/trinity/common/config.py
index 717a97b668..3b735bf4f3 100644
--- a/trinity/common/config.py
+++ b/trinity/common/config.py
@@ -3,6 +3,7 @@
 import os
 from dataclasses import dataclass, field
 from datetime import datetime
+from enum import Enum
 from typing import Any, Dict, List, Optional
 
 from omegaconf import OmegaConf
@@ -386,7 +387,7 @@ class MonitorConfig:
     # TODO: support multiple monitors (List[str])
     monitor_type: str = "tensorboard"
     # the default args for monitor
-    monitor_args: Dict = field(default_factory=dict)
+    monitor_args: Optional[Dict] = None
     # whether to enable ray timeline profile
     # the output file will be saved to `cache_dir/timeline.json`
     enable_ray_timeline: bool = False
@@ -793,6 +794,14 @@ def check_and_update(self) -> None:  # noqa: C901
 
         self._check_interval()
 
+        # check monitor
+        from trinity.utils.monitor import MONITOR
+
+        monitor_cls = MONITOR.get(self.monitor.monitor_type)
+        if monitor_cls is None:
+            raise ValueError(f"Invalid monitor type: {self.monitor.monitor_type}")
+        if self.monitor.monitor_args is None:
+            self.monitor.monitor_args = monitor_cls.default_args()
         # create a job dir in <checkpoint_root_dir>/<project>/<name>/monitor
         self.monitor.cache_dir = os.path.join(self.checkpoint_job_dir, "monitor")
         try:
@@ -831,6 +840,29 @@ def check_and_update(self) -> None:  # noqa: C901
         else:
             self.trainer.trainer_config = None
 
+    def flatten(self) -> Dict[str, Any]:
+        """Flatten the config into a single-level dict with dot-separated keys for nested fields."""
+
+        def _flatten(obj, parent_key="", sep="."):
+            items = {}
+            if hasattr(obj, "__dataclass_fields__"):
+                obj = vars(obj)
+            if isinstance(obj, dict):
+                for k, v in obj.items():
+                    new_key = f"{parent_key}{sep}{k}" if parent_key else k
+                    items.update(_flatten(v, new_key, sep=sep))
+            elif isinstance(obj, list):
+                for i, v in enumerate(obj):
+                    new_key = f"{parent_key}{sep}{i}" if parent_key else str(i)
+                    items.update(_flatten(v, new_key, sep=sep))
+            elif isinstance(obj, Enum):
+                items[parent_key] = obj.value
+            else:
+                items[parent_key] = obj
+            return items
+
+        return _flatten(self)
+
 
 def load_config(config_path: str) -> Config:
     """Load the configuration from the given path."""
diff --git a/trinity/utils/monitor.py b/trinity/utils/monitor.py
index 6ba4d7482d..75860357eb 100644
--- a/trinity/utils/monitor.py
+++ b/trinity/utils/monitor.py
@@ -6,7 +6,16 @@
 
 import numpy as np
 import pandas as pd
-import wandb
+
+try:
+    import wandb
+except ImportError:
+    wandb = None
+
+try:
+    import mlflow
+except ImportError:
+    mlflow = None
 from torch.utils.tensorboard import SummaryWriter
 
 from trinity.common.config import Config
@@ -77,6 +86,11 @@ def calculate_metrics(
                 metrics[key] = val
         return metrics
 
+    @classmethod
+    def default_args(cls) -> Dict:
+        """Return default arguments for the monitor."""
+        return {}
+
 
 @MONITOR.register_module("tensorboard")
 class TensorboardMonitor(Monitor):
@@ -103,11 +117,24 @@ def close(self) -> None:
 
 @MONITOR.register_module("wandb")
 class WandbMonitor(Monitor):
+    """Monitor with Weights & Biases.
+
+    Args:
+        base_url (`Optional[str]`): The base URL of the W&B server. If not provided, use the environment variable `WANDB_BASE_URL`.
+        api_key (`Optional[str]`): The API key for W&B. If not provided, use the environment variable `WANDB_API_KEY`.
+    """
+
     def __init__(
         self, project: str, group: str, name: str, role: str, config: Config = None
     ) -> None:
+        assert wandb is not None, "wandb is not installed. Please install it to use WandbMonitor."
         if not group:
             group = name
+        monitor_args = config.monitor.monitor_args or {}
+        if base_url := monitor_args.get("base_url"):
+            os.environ["WANDB_BASE_URL"] = base_url
+        if api_key := monitor_args.get("api_key"):
+            os.environ["WANDB_API_KEY"] = api_key
         self.logger = wandb.init(
             project=project,
             group=group,
@@ -129,3 +156,65 @@ def log(self, data: dict, step: int, commit: bool = False) -> None:
 
     def close(self) -> None:
         self.logger.finish()
+
+    @classmethod
+    def default_args(cls) -> Dict:
+        """Return default arguments for the monitor."""
+        return {
+            "base_url": None,
+            "api_key": None,
+        }
+
+
+@MONITOR.register_module("mlflow")
+class MlflowMonitor(Monitor):
+    """Monitor with MLflow.
+
+    Args:
+        uri (`Optional[str]`): The tracking server URI. If not provided, the default is `http://localhost:5000`.
+        username (`Optional[str]`): The username to login. If not provided, the default is `None`.
+        password (`Optional[str]`): The password to login. If not provided, the default is `None`.
+    """
+
+    def __init__(
+        self, project: str, group: str, name: str, role: str, config: Config = None
+    ) -> None:
+        assert (
+            mlflow is not None
+        ), "mlflow is not installed. Please install it to use MlflowMonitor."
+        monitor_args = config.monitor.monitor_args or {}
+        if username := monitor_args.get("username"):
+            os.environ["MLFLOW_TRACKING_USERNAME"] = username
+        if password := monitor_args.get("password"):
+            os.environ["MLFLOW_TRACKING_PASSWORD"] = password
+        mlflow.set_tracking_uri(config.monitor.monitor_args.get("uri", "http://localhost:5000"))
+        mlflow.set_experiment(project)
+        mlflow.start_run(
+            run_name=f"{name}_{role}",
+            tags={
+                "group": group,
+                "role": role,
+            },
+        )
+        mlflow.log_params(config.flatten())
+        self.console_logger = get_logger(__name__)
+
+    def log_table(self, table_name: str, experiences_table: pd.DataFrame, step: int):
+        pass
+
+    def log(self, data: dict, step: int, commit: bool = False) -> None:
+        """Log metrics."""
+        mlflow.log_metrics(metrics=data, step=step)
+        self.console_logger.info(f"Step {step}: {data}")
+
+    def close(self) -> None:
+        mlflow.end_run()
+
+    @classmethod
+    def default_args(cls) -> Dict:
+        """Return default arguments for the monitor."""
+        return {
+            "uri": "http://localhost:5000",
+            "username": None,
+            "password": None,
+        }