[Feat] Dynamic URI generated from forwarded headers (Kong, Nginx,...)

app/main.py

@@ -2,8 +2,9 @@
 """Main API application"""
 
 import logging
-from fastapi import FastAPI
+from fastapi import FastAPI, Request
 from opentelemetry import trace
+from starlette.middleware.base import BaseHTTPMiddleware
 from opentelemetry.sdk.resources import Resource
 from opentelemetry.sdk.trace import TracerProvider
 from opentelemetry.sdk.trace.export import ConsoleSpanExporter, BatchSpanProcessor, SimpleSpanProcessor
@@ -20,6 +21,7 @@
 from app.routers.task import task
 
 from . import config
+from .request_context import set_api_url_base, _api_url_base
 
 logging.basicConfig(
     level=logging.INFO,
@@ -48,6 +50,19 @@
 
 APP = FastAPI(servers=[{"url": config.API_URL_ROOT}], **config.API_CONFIG)
 
+
+class _ExternalRequestContextMiddleware(BaseHTTPMiddleware):
+    async def dispatch(self, request: Request, call_next):
+        token = _api_url_base.set(None)
+        try:
+            set_api_url_base(request)
+            return await call_next(request)
+        finally:
+            _api_url_base.reset(token)
+
+
+APP.add_middleware(_ExternalRequestContextMiddleware)
+
 if config.OPENTELEMETRY_ENABLED:
     FastAPIInstrumentor.instrument_app(APP)
 

app/request_context.py

@@ -0,0 +1,30 @@
+"""Per-request URL context derived from forwarding headers. (e.g. for Kong or other API gateways)"""
+from contextvars import ContextVar
+
+from fastapi import Request
+
+from . import config
+
+_api_url_base: ContextVar[str | None] = ContextVar("_api_url_base", default=None)
+
+
+def set_api_url_base(request: Request) -> None:
+    """Set the per-request API URL base from forwarding headers."""
+    host = (request.headers.get("x-forwarded-host") or
+            request.headers.get("host", "")).split(",")[0].strip()
+    proto = (request.headers.get("x-forwarded-proto") or
+             request.url.scheme).split(",")[0].strip()
+    prefix = (request.headers.get("x-forwarded-prefix")
+              or request.headers.get("x-script-name")
+              or "").rstrip("/")
+    api_url = config.API_URL.strip("/")
+    if host:
+        _api_url_base.set(f"{proto}://{host}{prefix}/{api_url}")
+
+
+def get_url_prefix() -> str:
+    """Return the per-request API URL base, or fall back to static config."""
+    value = _api_url_base.get()
+    if value:
+        return value
+    return f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}"

app/routers/account/models.py

@@ -2,7 +2,7 @@
 import datetime
 from pydantic import Field, computed_field, field_validator
 
-from ... import config
+from ...request_context import get_url_prefix
 from ...types.base import IRIBaseModel
 from ...types.scalars import AllocationUnit
 
@@ -26,7 +26,7 @@ def _norm_dt_field(cls, v):
     @property
     def self_uri(self) -> str:
         """Return the URI for this project resource."""
-        return f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}/account/projects/{self.id}"
+        return f"{get_url_prefix()}/account/projects/{self.id}"
 
 
 class AllocationEntry(IRIBaseModel):
@@ -54,13 +54,13 @@ class ProjectAllocation(IRIBaseModel):
     @property
     def project_uri(self) -> str:
         """Return the URI for the associated project resource."""
-        return f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}/account/projects/{self.project_id}"
+        return f"{get_url_prefix()}/account/projects/{self.project_id}"
 
     @computed_field(description="URI of the associated capability resource")
     @property
     def capability_uri(self) -> str:
         """Return the URI for the associated capability."""
-        return f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}/account/capabilities/{self.capability_id}"
+        return f"{get_url_prefix()}/account/capabilities/{self.capability_id}"
 
 
 class UserAllocation(IRIBaseModel):
@@ -79,4 +79,4 @@ class UserAllocation(IRIBaseModel):
     @property
     def project_allocation_uri(self) -> str:
         """Return the URI for the associated project allocation."""
-        return f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}/account/projects/{self.project_id}/project_allocations/{self.project_allocation_id}"
+        return f"{get_url_prefix()}/account/projects/{self.project_id}/project_allocations/{self.project_allocation_id}"

app/routers/facility/models.py

@@ -1,7 +1,7 @@
 """Facility-related models."""
 from pydantic import Field, HttpUrl, computed_field
 
-from ... import config
+from ...request_context import get_url_prefix
 from ...types.base import NamedObject
 
 
@@ -26,7 +26,7 @@ def _self_path(self) -> str:
     @property
     def resource_uris(self) -> list[str]:
         """Return the list of resource URIs for this site."""
-        return [f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}/status/resources/{resource_id}" for resource_id in self.resource_ids]
+        return [f"{get_url_prefix()}/status/resources/{resource_id}" for resource_id in self.resource_ids]
 
     @classmethod
     def find(cls, items, name=None, description=None, modified_since=None, short_name=None, country_name=None):
@@ -53,4 +53,4 @@ def _self_path(self) -> str:
     @property
     def site_uris(self) -> list[str]:
         """Return the list of site URIs for this facility."""
-        return [f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}/facility/sites/{site_id}" for site_id in self.site_ids]
+        return [f"{get_url_prefix()}/facility/sites/{site_id}" for site_id in self.site_ids]

app/routers/status/models.py

@@ -4,7 +4,7 @@
 
 from pydantic import Field, computed_field, field_validator
 
-from ... import config
+from ...request_context import get_url_prefix
 from ...types.base import NamedObject
 
 
@@ -43,13 +43,13 @@ def _self_path(self) -> str:
     @property
     def site_uri(self) -> str:
         """Return the site URI for this resource."""
-        return f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}/facility/sites/{self.site_id}"
+        return f"{get_url_prefix()}/facility/sites/{self.site_id}"
 
     @computed_field(description="The list of capabilities in this resource")
     @property
     def capability_uris(self) -> list[str]:
         """Return the list of capability URIs for this resource."""
-        return [f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}/account/capabilities/{e}" for e in self.capability_ids]
+        return [f"{get_url_prefix()}/account/capabilities/{e}" for e in self.capability_ids]
 
     @classmethod
     def find(cls, items, name=None, description=None, modified_since=None, group=None, resource_type=None, current_status=None, capability=None, site_id=None) -> list:
@@ -89,13 +89,13 @@ def _norm_dt_field(cls, v):
     @property
     def resource_uri(self) -> str:
         """Return the resource URI for this event."""
-        return f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}/status/resources/{self.resource_id}"
+        return f"{get_url_prefix()}/status/resources/{self.resource_id}"
 
     @computed_field(description="The event's incident")
     @property
     def incident_uri(self) -> str | None:
         """Return the incident URI for this event."""
-        return f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}/status/incidents/{self.incident_id}" if self.incident_id else None
+        return f"{get_url_prefix()}/status/incidents/{self.incident_id}" if self.incident_id else None
 
     @classmethod
     def find(cls, items, incident_id=None, name=None, description=None, modified_since=None, resource_id=None, status=None, from_=None, to=None, time_=None) -> list:
@@ -162,13 +162,13 @@ def _norm_dt_field(cls, v):
     @property
     def event_uris(self) -> list[str]:
         """Return the list of event URIs for this incident."""
-        return [f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}/status/events/{e}" for e in self.event_ids]
+        return [f"{get_url_prefix()}/status/events/{e}" for e in self.event_ids]
 
     @computed_field(description="The list of resources that may be impacted by this incident")
     @property
     def resource_uris(self) -> list[str]:
         """Return the list of resource URIs for this incident."""
-        return [f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}/status/resources/{r}" for r in self.resource_ids]
+        return [f"{get_url_prefix()}/status/resources/{r}" for r in self.resource_ids]
 
     @classmethod
     def find(cls, items, name=None, description=None, modified_since=None, status=None, type_=None, from_=None, to=None, time_=None, resource_id=None, resolution=None) -> list:

app/routers/task/models.py

@@ -2,7 +2,7 @@
 import enum
 from pydantic import BaseModel, Field, computed_field
 
-from ... import config
+from ...request_context import get_url_prefix
 
 
 class TaskSubmitResponse(BaseModel):
@@ -13,7 +13,7 @@ class TaskSubmitResponse(BaseModel):
     @property
     def task_uri(self) -> str:
         """Return the URI for this task."""
-        return f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}/task/{self.task_id}"
+        return f"{get_url_prefix()}/task/{self.task_id}"
 
 
 class TaskStatus(str, enum.Enum):

app/types/base.py

@@ -5,6 +5,7 @@
 from pydantic import BaseModel, ConfigDict, Field, computed_field, field_validator, model_serializer
 
 from .. import config
+from ..request_context import get_url_prefix
 from .scalars import StrictDateTime
 
 
@@ -59,7 +60,7 @@ def _norm_dt_field(cls, v):
     @property
     def self_uri(self) -> str:
         """Computed self URI property."""
-        return f"{config.API_URL_ROOT}{config.API_PREFIX}{config.API_URL}{self._self_path()}"
+        return f"{get_url_prefix()}{self._self_path()}"
 
     name: str|None = Field(default=None, description="The long name of the object.", example="Perlmutter GPU")
     description: str|None = Field(default=None, description="Human-readable description of the object.", example="High-performance GPU compute resource")