Merge pull request #1046 from lsst/tickets/DM-45616

DM-45616: Add a way for Butler server to serve static files

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

@@ -0,0 +1,54 @@
+# 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/>.
+
+from __future__ import annotations
+
+import dataclasses
+import os
+
+
+@dataclasses.dataclass(frozen=True)
+class ButlerServerConfig:
+    """Butler server configuration loaded from environment variables.
+
+    Notes
+    -----
+    Besides these variables, there is one critical environment variable.  The
+    list of repositories to be hosted must be defined using
+     ``DAF_BUTLER_REPOSITORIES`` or ``DAF_BUTLER_REPOSITORY_INDEX`` -- see
+     `ButlerRepoIndex`.
+    """
+
+    static_files_path: str | None
+    """Absolute path to a directory of files that will be served to end-users
+    as static files from the `configs/` HTTP route.
+    """
+
+
+def load_config() -> ButlerServerConfig:
+    """Read the Butler server configuration from the environment."""
+    return ButlerServerConfig(static_files_path=os.environ.get("DAF_BUTLER_SERVER_STATIC_FILES_PATH"))

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

@@ -34,11 +34,13 @@
 import safir.dependencies.logger
 from fastapi import FastAPI, Request, Response
 from fastapi.middleware.gzip import GZipMiddleware
+from fastapi.staticfiles import StaticFiles
 from safir.logging import configure_logging, configure_uvicorn_logging
 
 from ..._exceptions import ButlerUserError
 from .._errors import serialize_butler_user_error
 from ..server_models import CLIENT_REQUEST_ID_HEADER_NAME, ERROR_STATUS_CODE, ErrorResponseModel
+from ._config import load_config
 from .handlers._external import external_router
 from .handlers._external_query import query_router
 from .handlers._internal import internal_router
@@ -49,6 +51,8 @@
 
 def create_app() -> FastAPI:
     """Create a Butler server FastAPI application."""
+    config = load_config()
+
     app = FastAPI()
     app.add_middleware(GZipMiddleware, minimum_size=1000)
 
@@ -67,6 +71,17 @@ def create_app() -> FastAPI:
         )
     app.include_router(internal_router)
 
+    # If configured to do so, serve a directory of static files via HTTP.
+    #
+    # Until we are able to fully transition away from DirectButler for the RSP,
+    # we need a place to host DirectButler configuration files. Since this
+    # same configuration is needed for Butler server, it's easier to configure
+    # in Phalanx if we just host them from Butler server itself.
+    # This will also host the end-user repository index file for the RSP, for
+    # lack of a better place to put it.
+    if config.static_files_path:
+        app.mount(f"{default_api_path}/configs", StaticFiles(directory=config.static_files_path))
+
     # Any time an exception is returned by a handler, add a log message that
     # includes the username and request ID from the client.  This will make it
     # easier to track down user-reported issues in the logs.

python/lsst/daf/butler/tests/server_utils.py

@@ -70,5 +70,7 @@ def _is_authenticated_endpoint(path: str) -> bool:
         return False
     if path.endswith("/butler.json"):
         return False
+    if path.startswith("/api/butler/configs"):
+        return False
 
     return True

tests/test_server.py

@@ -26,6 +26,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import os.path
+import tempfile
 import unittest
 import uuid
 
@@ -106,6 +107,17 @@ def test_health_check(self):
         self.assertEqual(response.status_code, 200)
         self.assertEqual(response.json()["name"], "butler")
 
+    def test_static_files(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            with open(os.path.join(tmpdir, "temp.txt"), "w") as fh:
+                fh.write("test data 123")
+
+            with mock_env({"DAF_BUTLER_SERVER_STATIC_FILES_PATH": tmpdir}):
+                with create_test_server(TESTDIR) as server:
+                    response = server.client.get("/api/butler/configs/temp.txt")
+                    self.assertEqual(response.status_code, 200)
+                    self.assertEqual(response.text, "test data 123")
+
     def test_dimension_universe(self):
         universe = self.butler.dimensions
         self.assertEqual(universe.namespace, "daf_butler")