Do not force mlflow usage

Closes #29 (closed)

dan/ocr/document/train.py

@@ -5,20 +5,28 @@ import random
 from copy import deepcopy
 from pathlib import Path
 
-import mlflow
 import numpy as np
 import torch
 import torch.multiprocessing as mp
 from torch.optim import Adam
 
+from dan import logger
 from dan.decoder import GlobalHTADecoder
 from dan.manager.ocr import OCRDataset, OCRDatasetManager
 from dan.manager.training import Manager
-from dan.mlflow import start_mlflow_run
+from dan.mlflow import MLflowNotInstalled, start_mlflow_run
 from dan.models import FCN_Encoder
 from dan.schedulers import exponential_dropout_scheduler
 from dan.transforms import aug_config
 
+try:
+    import mlflow
+
+    MLFLOW = True
+    logger.info("MLflow Logging available.")
+except ImportError:
+    MLFLOW = False
+
 logger = logging.getLogger(__name__)
 
 
@@ -272,13 +280,14 @@ def run():
     config = get_config()
     config_artifact = serialize_config(config)
     labels_artifact = ""
-    dataset_name = config["mlflow"]["dataset_name"]
+    # The only key of this dict is the name of the dataset
+    dataset_name = config_artifact["dataset_params"]["datasets"].keys()[0]
     labels_path = (
         Path(config_artifact["dataset_params"]["datasets"][dataset_name])
         / "labels.json"
     )
 
-    if config["mlflow"]:
+    if MLFLOW and config["mlflow"]:
         with start_mlflow_run(config["mlflow"]) as run:
             logger.info(f"Set tags to MLflow on {config['mlflow']['run_name']}")
             mlflow.set_tags({"Dataset": config["mlflow"]["dataset_name"]})
@@ -303,6 +312,11 @@ def run():
                 )
             else:
                 train_and_test(0, config, True)
+    elif config["mlflow"]:
+        logger.error(
+            "Cannot log to MLflow as the `mlflow` module was not found in your environment."
+        )
+        raise MLflowNotInstalled()
     else:
         if (
             config["training_params"]["use_ddp"]