Added a root_path config parameter that allows to configure the fasta…

…pi app root_path.

optimade/server/config.py

@@ -74,6 +74,13 @@ class ServerConfig(BaseSettings):
         "test_server",
         description="ID of /links endpoint resource for the chosen default OPTIMADE implementation (only relevant for the index meta-database)",
     )
+    root_path: Optional[str] = Field(
+        None,
+        description=(
+            "Fastapi root_path app parameter. This can be used to serve the API under a "
+            "path prefix behind a proxy or as a sub application of another fastapi app."
+        ),
+    )
     base_url: Optional[str] = Field(
         None, description="Base URL for this implementation"
     )

optimade/server/main.py

@@ -45,6 +45,7 @@
     LOGGER.info("DEBUG MODE")
 
 app = FastAPI(
+    root_path=CONFIG.root_path,
     title="OPTIMADE API",
     description=(
         f"""The [Open Databases Integration for Materials Design (OPTIMADE) consortium](https://www.optimade.org/) aims to make materials databases interoperational by developing a common REST API.