Intermediate changes

commit_hash:1623077a586fe91fb5d853b4efee5d1e623189cb

3 files changed, 45 insertions, 1 deletions

diff --git a/library/python/find_root/README.md b/library/python/find_root/README.md
new file mode 100644
index 00000000000..9a370d2f2ff
--- /dev/null
+++ b/library/python/find_root/README.md
@@ -0,0 +1,9 @@
+# find_root
+
+A simple library for Arcadia root detection.
+
+Простая библиотека для обнаружения корня Аркадии.
+
+Имеется два варианта детектора:
+- каноническая версия `detect_root` (смотрит только на файловую систему)
+- расширенная `get_arcadia_root` + `try_get_arcadia_root` (смотрит на переменные окружения)
diff --git a/library/python/find_root/__init__.py b/library/python/find_root/__init__.py
index 6da604d62e1..5cf6625ad95 100644
--- a/library/python/find_root/__init__.py
+++ b/library/python/find_root/__init__.py
@@ -18,3 +18,36 @@ def _find_path(starts_from, check):
         if next_p == p:
             return None
         p = next_p
+
+
+def try_get_arcadia_root(start_path=os.path.abspath(__file__)):
+    """
+    Extended Arcadia root lookup: use various env vars
+    :param start_path: initial path for lookup
+    Obtain Arcadia root or **empty string** when arcadia root cannot be found.
+    """
+    env_root = os.getenv("ARCADIA_ROOT")
+    if env_root:
+        return env_root
+
+    path = start_path
+    while path != "/" and not os.path.exists(os.path.join(path, ".arcadia.root")):
+        path = os.path.dirname(path)
+
+    # if after all, we reached root, try to check up from ya path
+    # env variable "_" contains path to ya
+    if path == "/" and start_path == os.path.abspath(__file__):
+        path = try_get_arcadia_root(os.path.dirname(os.getenv("_")))
+
+    return path if path != "/" else ""
+
+
+def get_arcadia_root(start_path=os.path.abspath(__file__)):
+    """
+    :param start_path: initial path for lookup
+    Obtain Arcadia root or raise exception when root cannot be found.
+    """
+    arcadia_root = try_get_arcadia_root(start_path=start_path)
+    if not arcadia_root:
+        raise Exception("Cannot find Arcadia root")
+    return arcadia_root
diff --git a/library/python/find_root/ya.make b/library/python/find_root/ya.make
index 35821361805..235c6295674 100644
--- a/library/python/find_root/ya.make
+++ b/library/python/find_root/ya.make
@@ -1,5 +1,7 @@
 PY23_LIBRARY()
 
-PY_SRCS(__init__.py)
+ALL_PY_SRCS()
+
+STYLE_RUFF()
 
 END()