Add an environment variable for server config

python/lsst/daf/butler/remote_butler/server/_config.py

@@ -0,0 +1,46 @@
+# This file is part of daf_butler.
+#
+# Developed for the LSST Data Management System.
+# This product includes software developed by the LSST Project
+# (http://www.lsst.org).
+# See the COPYRIGHT file at the top-level directory of this distribution
+# for details of code ownership.
+#
+# This software is dual licensed under the GNU General Public License and also
+# under a 3-clause BSD license. Recipients may choose which of these licenses
+# to use; please see the files gpl-3.0.txt and/or bsd_license.txt,
+# respectively.  If you choose the GPL option then the following text applies
+# (but note that there is still no warranty even if you opt for BSD instead):
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+from dataclasses import dataclass
+
+__all__ = ("Config", "get_config_from_env")
+
+
+@dataclass(frozen=True)
+class Config:
+    butler_root: str
+
+
+def get_config_from_env() -> Config:
+    butler_root = os.getenv("BUTLER_SERVER_BUTLER_ROOT")
+    if butler_root is None:
+        raise Exception(
+            "The environment variable BUTLER_SERVER_BUTLER_ROOT "
+            "must point to a Butler configuration to be used by the server"
+        )
+    return Config(butler_root=butler_root)

python/lsst/daf/butler/remote_butler/server/_server.py

@@ -37,10 +37,9 @@
 from fastapi.middleware.gzip import GZipMiddleware
 from lsst.daf.butler import Butler
 
+from ._config import get_config_from_env
 from ._factory import Factory
 
-BUTLER_ROOT = "ci_hsc_gen3/DATA"
-
 log = logging.getLogger(__name__)
 
 app = FastAPI()
@@ -49,7 +48,8 @@
 
 @cache
 def _make_global_butler() -> Butler:
-    return Butler.from_config(BUTLER_ROOT)
+    config = get_config_from_env()
+    return Butler.from_config(config.butler_root)
 
 
 def factory_dependency() -> Factory: