refactor(env): introduce explicit gym ID handling in EnvConfig/factory (#2234)

* refactor(env): introduce explicit gym ID handling in EnvConfig/factory

This commit introduces properties for the gym package/ID associated
with and environment config. They default to the current defaults
(`gym_{package_name}/{task_id}`) to avoid breaking changes, but allow
for easier use of external gym environments.

Subclasses of `EnvConfig` can override the default properties to allow
the factory to import (i.e. register) the gym env from a specific module,
and also instantiate the env from any ID string.

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* more changes

* quality

* fix test

---------

Co-authored-by: Ben Sprenger <ben.sprenger@rogers.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Adil Zouitine <adilzouitinegm@gmail.com>

src/lerobot/envs/configs.py

@@ -37,6 +37,16 @@ class EnvConfig(draccus.ChoiceRegistry, abc.ABC):
     def type(self) -> str:
         return self.get_choice_name(self.__class__)
 
+    @property
+    def package_name(self) -> str:
+        """Package name to import if environment not found in gym registry"""
+        return f"gym_{self.type}"
+
+    @property
+    def gym_id(self) -> str:
+        """ID string used in gym.make() to instantiate the environment"""
+        return f"{self.package_name}/{self.task}"
+
     @property
     @abc.abstractmethod
     def gym_kwargs(self) -> dict:

src/lerobot/envs/factory.py

@@ -16,6 +16,7 @@
 import importlib
 
 import gymnasium as gym
+from gymnasium.envs.registration import registry as gym_registry
 
 from lerobot.envs.configs import AlohaEnv, EnvConfig, LiberoEnv, PushtEnv
 
@@ -84,17 +85,24 @@ def make_env(
             gym_kwargs=cfg.gym_kwargs,
             env_cls=env_cls,
         )
-    package_name = f"gym_{cfg.type}"
-    try:
-        importlib.import_module(package_name)
-    except ModuleNotFoundError as e:
-        print(f"{package_name} is not installed. Please install it with `pip install 'lerobot[{cfg.type}]'`")
-        raise e
 
-    gym_handle = f"{package_name}/{cfg.task}"
+    if cfg.gym_id not in gym_registry:
+        print(f"gym id '{cfg.gym_id}' not found, attempting to import '{cfg.package_name}'...")
+        try:
+            importlib.import_module(cfg.package_name)
+        except ModuleNotFoundError as e:
+            raise ModuleNotFoundError(
+                f"Package '{cfg.package_name}' required for env '{cfg.type}' not found. "
+                f"Please install it or check PYTHONPATH."
+            ) from e
+
+        if cfg.gym_id not in gym_registry:
+            raise gym.error.NameNotFound(
+                f"Environment '{cfg.gym_id}' not registered even after importing '{cfg.package_name}'."
+            )
 
     def _make_one():
-        return gym.make(gym_handle, disable_env_checker=cfg.disable_env_checker, **(cfg.gym_kwargs or {}))
+        return gym.make(cfg.gym_id, disable_env_checker=cfg.disable_env_checker, **(cfg.gym_kwargs or {}))
 
     vec = env_cls([_make_one for _ in range(n_envs)], autoreset_mode=gym.vector.AutoresetMode.SAME_STEP)