dynamic conda finding

tracking_re_id/launch/_conda_utils.py

@@ -0,0 +1,66 @@
+"""Utilities for locating conda-environment Python interpreters at launch time."""
+
+import os
+
+
+def find_conda_python(env_name: str) -> str:
+    """Return the path to ``python3`` inside a named conda environment.
+
+    Resolution order
+    ----------------
+    1. ``<ENV_NAME_UPPER>_PYTHON`` environment variable (explicit override).
+       e.g. for *mmpose*: ``MMPOSE_PYTHON=/path/to/python3``
+    2. ``CONDA_EXE`` environment variable — set by ``conda init`` and points to
+       the conda binary inside the base installation.  The base directory is two
+       levels up (``<base>/bin/conda → <base>``).
+    3. A scan of common conda base-directory locations.
+
+    Parameters
+    ----------
+    env_name:
+        Name of the conda environment (e.g. ``"mmpose"``).
+
+    Returns
+    -------
+    str
+        Absolute path to the Python 3 interpreter.
+
+    Raises
+    ------
+    FileNotFoundError
+        If no interpreter is found through any of the above methods.
+    """
+    # 1. Explicit override via environment variable
+    override_var = f"{env_name.upper()}_PYTHON"
+    if p := os.environ.get(override_var):
+        return p
+
+    rel = os.path.join("envs", env_name, "bin", "python3")
+
+    # 2. Derive conda base from CONDA_EXE (most reliable when conda is initialised)
+    if conda_exe := os.environ.get("CONDA_EXE"):
+        base = os.path.dirname(os.path.dirname(conda_exe))
+        candidate = os.path.join(base, rel)
+        if os.path.isfile(candidate):
+            return candidate
+
+    # 3. Scan common install locations
+    common_bases = [
+        "~/miniconda3",
+        "~/anaconda3",
+        "~/mambaforge",
+        "~/miniforge3",
+        "~/opt/miniconda3",
+        "/opt/conda",
+        "/opt/miniconda3",
+        "/opt/anaconda3",
+    ]
+    for base in common_bases:
+        candidate = os.path.join(os.path.expanduser(base), rel)
+        if os.path.isfile(candidate):
+            return candidate
+
+    raise FileNotFoundError(
+        f"Cannot locate Python for conda env '{env_name}'. "
+        f"Set the {override_var} environment variable to the full path of the interpreter."
+    )