Make experiment tracking optional (#226)

* Make experiment tracking optional

trlx/trainer/accelerate_base_trainer.py

@@ -76,17 +76,16 @@ def __init__(self, config, **kwargs):
 
         run_name = "/".join([script_name, model_name, num_gpus]) + f":{branch}"
 
-        if self.accelerator.is_main_process and not ray.is_initialized():
+        if (
+            config.train.tracker is not None
+            and self.accelerator.is_main_process
+            and not ray.is_initialized()
+        ):
             config_dict = self.config.to_dict()
             dist_config = get_distributed_config(self.accelerator)
             config_dict["distributed"] = dist_config
             init_trackers_kwargs = {}
 
-            if config.train.tracker not in ("wandb", "tensorboard"):
-                raise ValueError(
-                    f"Only supported trackers are wandb and tensorboard, got {config.train.tracker}"
-                )
-
             if config.train.tracker == "wandb":
                 init_trackers_kwargs["wandb"] = {
                     "name": run_name,
@@ -101,7 +100,7 @@ def __init__(self, config, **kwargs):
                     config=config_dict,
                     init_kwargs=init_trackers_kwargs,
                 )
-            else:  # only other supported tracker is tensorboard
+            elif config.train.tracker == "tensorboard":
                 config_dict_flat = flatten_dict(
                     config_dict
                 )  # flatten config for tensorboard, split list in hparams into flatten config
@@ -116,6 +115,11 @@ def __init__(self, config, **kwargs):
                     project_name=self.config.train.project_name,
                     config=config_dict_flat,
                 )
+            else:
+                raise ValueError(
+                    f"Only supported trackers are `wandb` and `tensorboard`. Got: `{config.train.tracker}`. "
+                    "Set `tracker` to `None` to disable tracking."
+                )
 
     def setup_model(self):
         """