[Feature] Add modular tracking interface with MLflow backend

miles/utils/arguments.py

@@ -1048,6 +1048,30 @@ def add_wandb_arguments(parser):
             parser.add_argument("--wandb-run-id", type=str, default=None)
             return parser
 
+        # mlflow
+        def add_mlflow_arguments(parser):
+            parser.add_argument("--use-mlflow", action="store_true", default=False)
+            parser.add_argument(
+                "--mlflow-tracking-uri",
+                type=str,
+                default=None,
+                help="MLflow tracking server URI. Defaults to MLFLOW_TRACKING_URI env var, or local mlruns/ directory.",
+            )
+            parser.add_argument(
+                "--mlflow-experiment-name",
+                type=str,
+                default="miles",
+                help="MLflow experiment name.",
+            )
+            parser.add_argument(
+                "--mlflow-run-name",
+                type=str,
+                default=None,
+                help="MLflow run name. Defaults to --wandb-group if not set.",
+            )
+            parser.add_argument("--mlflow-run-id", type=str, default=None)
+            return parser
+
         # tensorboard
         def add_tensorboard_arguments(parser):
             # tb_project_name, tb_experiment_name
@@ -1397,6 +1421,7 @@ def add_sglang_tp_size():
         parser = add_eval_arguments(parser)
         parser = add_algo_arguments(parser)
         parser = add_wandb_arguments(parser)
+        parser = add_mlflow_arguments(parser)
         parser = add_tensorboard_arguments(parser)
         parser = add_router_arguments(parser)
         parser = add_debug_arguments(parser)

miles/utils/tracking/__init__.py

@@ -0,0 +1 @@
+from .base import TrackingBackend, TrackingManager, BACKEND_REGISTRY

miles/utils/tracking/base.py

@@ -0,0 +1,137 @@
+"""
+Shared tracking interface for experiment logging backends.
+
+Each backend implements ``init / log / finish``, and :class:`TrackingManager` fans out
+calls to every active backend.
+
+To add a new backend:
+--------------------
+1. Subclass :class:`TrackingBackend`.
+2. Register it in :data:`BACKEND_REGISTRY`.
+3. Add a corresponding ``--use-<name>`` CLI flag in ``arguments.py``.
+"""
+
+from __future__ import annotations
+
+import logging
+from abc import ABC, abstractmethod
+from typing import Any
+
+logger = logging.getLogger(__name__)
+
+
+
+class TrackingBackend(ABC):
+    # Interface every logging backend must satisfy.
+
+    @abstractmethod
+    def init(self, args, *, primary: bool = True, **kwargs) -> None:
+        ...
+
+    @abstractmethod
+    def log(self, metrics: dict[str, Any], step: int | None = None) -> None:
+        ...
+
+    @abstractmethod
+    def finish(self) -> None:
+        ...
+
+
+# Thin adapters for backwards compatibility to keep wandb_utils and tensorboard_utils untouched.
+class WandbBackend(TrackingBackend):
+    # Delegates to the existing ``wandb_utils`` helpers.
+
+    def init(self, args, *, primary: bool = True, **kwargs) -> None:
+        from . import wandb_utils
+
+        if primary:
+            wandb_utils.init_wandb_primary(args, **kwargs)
+        else:
+            wandb_utils.init_wandb_secondary(args, **kwargs)
+
+    def log(self, metrics: dict[str, Any], step: int | None = None) -> None:
+        import wandb
+
+        wandb.log(metrics)
+
+    def finish(self) -> None:
+        import wandb
+
+        wandb.finish()
+
+
+class TensorboardBackend(TrackingBackend):
+    _adapter = None
+
+    def init(self, args, *, primary: bool = True, **kwargs) -> None:
+        from .tensorboard_utils import _TensorboardAdapter
+
+        self._adapter = _TensorboardAdapter(args)
+
+    def log(self, metrics: dict[str, Any], step: int | None = None) -> None:
+        if self._adapter is not None:
+            # Strip step-key entries (e.g. "train/step", "rollout/step") —
+            # tensorboard receives step as an explicit argument instead.
+            data = {k: v for k, v in metrics.items() if not k.endswith("/step")}
+            self._adapter.log(data=data, step=step)
+
+    def finish(self) -> None:
+        if self._adapter is not None:
+            self._adapter.finish()
+
+
+class MlflowBackend(TrackingBackend):
+
+    def init(self, args, *, primary: bool = True, **kwargs) -> None:
+        from . import mlflow_utils
+
+        mlflow_utils.init_mlflow(args, primary=primary, **kwargs)
+
+    def log(self, metrics: dict[str, Any], step: int | None = None) -> None:
+        from . import mlflow_utils
+
+        mlflow_utils.log_metrics(metrics, step=step)
+
+    def finish(self) -> None:
+        from . import mlflow_utils
+
+        mlflow_utils.finish()
+
+
+# Registry that maps backend name → (class, args-flag attribute)
+
+BACKEND_REGISTRY: dict[str, tuple[type[TrackingBackend], str]] = {
+    "wandb": (WandbBackend, "use_wandb"),
+    "tensorboard": (TensorboardBackend, "use_tensorboard"),
+    "mlflow": (MlflowBackend, "use_mlflow"),
+}
+
+
+class TrackingManager:
+    #Initialises and logs to every enabled backend; used internally by ``tracking_utils``.
+
+    def __init__(self) -> None:
+        self._backends: list[TrackingBackend] = []
+
+    def init(self, args, *, primary: bool = True, **kwargs) -> None:
+        for name, (cls, flag) in BACKEND_REGISTRY.items():
+            if getattr(args, flag, False):
+                logger.info("Initialising tracking backend: %s", name)
+                backend = cls()
+                backend.init(args, primary=primary, **kwargs)
+                self._backends.append(backend)
+
+    def log(self, metrics: dict[str, Any], step: int | None = None) -> None:
+        for backend in self._backends:
+            backend.log(metrics, step=step)
+
+    def finish(self) -> None:
+        for backend in self._backends:
+            try:
+                backend.finish()
+            except Exception:
+                logger.exception(
+                    "Error finishing tracking backend %s",
+                    type(backend).__name__,
+                )
+        self._backends.clear()

miles/utils/tracking/mlflow_utils.py

@@ -0,0 +1,135 @@
+"""
+MLflow tracking backend for slime.
+
+
+MLflow docs for future reference:
+  - Tracking overview : https://mlflow.org/docs/latest/ml/tracking/
+  - Python API        : https://mlflow.org/docs/latest/python_api/mlflow.html
+  - Remote tracking   : https://mlflow.org/docs/latest/tracking/server.html
+"""
+
+from __future__ import annotations
+
+import logging
+import os
+import re
+from copy import deepcopy
+from typing import Any
+
+logger = logging.getLogger(__name__)
+
+
+# Helpers/utils
+def _sanitize_key(key: str) -> str:
+    return re.sub(r"[^a-zA-Z0-9_\-./\s]", "_", key)
+
+
+def _compute_config_for_logging(args) -> dict[str, str]:
+    # Build a flat param dict from *args*, mirroring ``wandb_utils._compute_config_for_logging``."""
+    raw = deepcopy(args.__dict__)
+
+    whitelist_env_vars = ["SLURM_JOB_ID"]
+    raw["env_vars"] = {k: v for k, v in os.environ.items() if k in whitelist_env_vars}
+
+    return _flatten_dict(raw)
+
+
+def _flatten_dict(d: dict, parent_key: str = "", sep: str = ".") -> dict[str, str]:
+    # Recursively flatten nested dicts into ``dotted.key`` → ``str(value)`` pairs.
+    items: list[tuple[str, str]] = []
+    for k, v in d.items():
+        new_key = f"{parent_key}{sep}{k}" if parent_key else k
+        if isinstance(v, dict):
+            items.extend(_flatten_dict(v, new_key, sep).items())
+        else:
+            items.append((new_key, str(v)))
+    return dict(items)
+
+
+def init_mlflow(args, *, primary: bool = True, **kwargs) -> None:
+    if not args.use_mlflow:
+        args.mlflow_run_id = None
+        return
+
+    import mlflow
+
+    tracking_uri = args.mlflow_tracking_uri or os.environ.get("MLFLOW_TRACKING_URI")
+    if tracking_uri:
+        mlflow.set_tracking_uri(tracking_uri)
+        logger.info("MLflow tracking URI: %s", tracking_uri)
+
+    experiment_name = args.mlflow_experiment_name
+    mlflow.set_experiment(experiment_name)
+
+    if primary:
+        _init_mlflow_primary(args, experiment_name)
+    else:
+        _init_mlflow_secondary(args)
+
+
+def _init_mlflow_primary(args, experiment_name: str) -> None:
+    import mlflow
+
+    run_name = args.mlflow_run_name or args.wandb_group
+
+    tags = {}
+    slurm_job_id = os.environ.get("SLURM_JOB_ID")
+    if slurm_job_id:
+        tags["slurm_job_id"] = slurm_job_id
+    tags["rank"] = str(args.rank)
+
+    run = mlflow.start_run(run_name=run_name, tags=tags)
+    mlflow.log_params(_compute_config_for_logging(args))
+
+    args.mlflow_run_id = run.info.run_id
+    logger.info("MLflow run started: %s (experiment=%s, name=%s)", run.info.run_id, experiment_name, run_name)
+
+
+def _init_mlflow_secondary(args) -> None:
+    """Attach to an existing MLflow run created by the primary rank."""
+    import mlflow
+
+    run_id = args.mlflow_run_id or os.environ.get("MLFLOW_RUN_ID")
+    if run_id is None:
+        return
+
+    mlflow.start_run(run_id=run_id)
+    logger.info("MLflow secondary attached to run: %s", run_id)
+
+
+# ---------------------------------------------------------------------------
+# Logging
+# ---------------------------------------------------------------------------
+
+def log_metrics(metrics: dict[str, Any], step: int | None = None) -> None:
+    import mlflow
+
+    if mlflow.active_run() is None:
+        return
+
+    sanitized: dict[str, float] = {}
+    for k, v in metrics.items():
+        if k.endswith("/step"):
+            continue
+        try:
+            sanitized[_sanitize_key(k)] = float(v)
+        except (TypeError, ValueError):
+            continue
+
+    if sanitized:
+        mlflow.log_metrics(sanitized, step=int(step) if step is not None else None)
+
+
+# ---------------------------------------------------------------------------
+# Cleanup
+# ---------------------------------------------------------------------------
+
+def finish() -> None:
+    import mlflow
+
+    if mlflow.active_run() is None:
+        return
+
+    run_id = mlflow.active_run().info.run_id
+    mlflow.end_run()
+    logger.info("MLflow run ended: %s", run_id)

miles/utils/tracking_utils.py

@@ -1,21 +1,16 @@
-import wandb
-from miles.utils.tensorboard_utils import _TensorboardAdapter
+from .tracking import TrackingManager
 
-from . import wandb_utils
+_manager = TrackingManager()
 
 
 def init_tracking(args, primary: bool = True, **kwargs):
-    if primary:
-        wandb_utils.init_wandb_primary(args, **kwargs)
-    else:
-        wandb_utils.init_wandb_secondary(args, **kwargs)
+    _manager.init(args, primary=primary, **kwargs)
 
 
-# TODO further refactor, e.g. put TensorBoard init to the "init" part
 def log(args, metrics, step_key: str):
-    if args.use_wandb:
-        wandb.log(metrics)
+    step = metrics.get(step_key)
+    _manager.log(metrics, step=step)
 
-    if args.use_tensorboard:
-        metrics_except_step = {k: v for k, v in metrics.items() if k != step_key}
-        _TensorboardAdapter(args).log(data=metrics_except_step, step=metrics[step_key])
+
+def finish_tracking():
+    _manager.finish()

setup.py

@@ -39,7 +39,10 @@ def get_tag(self):
     extras_require={
         "fsdp": [
             "torch>=2.0",
-        ]
+        ],
+        "mlflow": [
+            "mlflow",
+        ],
     },
     python_requires=">=3.10",
     classifiers=[