Remove cache buffer thing

Make the client use something like min-fresh in requests for ensuring a good buffer

services/dcs/src/dcs/adapters/inbound/fastapi_/routes.py

@@ -107,11 +107,8 @@ async def get_drs_object(
     if not work_order_context.file_id == object_id:
         raise http_exceptions.HttpWrongFileAuthorizationError()
 
-    # Instruct clients to refresh their download URL shortly before it expires
     expires_after = config.presigned_url_expires_after
-    buffer = config.url_expiration_buffer
-    url_max_age = max(buffer, expires_after - buffer)
-    cache_control_header = {"Cache-Control": f"max-age={url_max_age}"}
+    cache_control_header = {"Cache-Control": f"max-age={expires_after}"}
     try:
         drs_object = await data_repository.access_drs_object(drs_id=object_id)
         return Response(

services/dcs/src/dcs/core/data_repository.py

@@ -28,7 +28,7 @@
     S3ObjectStoragesConfig,
 )
 from hexkit.protocols.objstorage import ObjectStorageProtocol
-from pydantic import Field, PositiveInt, field_validator, model_validator
+from pydantic import Field, PositiveInt, field_validator
 from pydantic_settings import BaseSettings
 
 from dcs.adapters.outbound.http import exceptions
@@ -89,14 +89,6 @@ class DataRepositoryConfig(BaseSettings):
         title="Presigned URL expiration time in seconds",
         examples=[30, 60],
     )
-    url_expiration_buffer: PositiveInt = Field(
-        default=5,
-        description="Buffer time in seconds before the presigned URL expires, used to"
-        + " instruct clients to refresh their download URL shortly before it expires."
-        + " Should be less than presigned_url_expires_after.",
-        title="Download URL expiration buffer time (sec)",
-        examples=[5, 10],
-    )
     cache_timeout: int = Field(
         default=7,
         description="Time in days since last access after which a file present in the "
@@ -118,19 +110,6 @@ def check_server_uri(cls, value: str):
 
         return value
 
-    @model_validator(mode="after")
-    def check_url_expiration_buffer(self):
-        """Check that the buffer is less than the expiration time."""
-        value = self.url_expiration_buffer
-        if value >= self.presigned_url_expires_after:
-            message = (
-                "url_expiration_buffer must be less than presigned_url_expires_after"
-                + f", got: {value} (should be less than"
-                + f" {self.presigned_url_expires_after})"
-            )
-            raise ValueError(message)
-        return self
-
 
 class DataRepository(DataRepositoryPort):
     """A service that manages a registry of DRS objects."""

services/dcs/tests_dcs/test_edge_cases.py

@@ -17,20 +17,15 @@
 
 import re
 from dataclasses import dataclass
-from unittest.mock import AsyncMock
 
 import httpx
 import pytest
 import pytest_asyncio
 from fastapi import status
-from ghga_service_commons.api.testing import AsyncTestClient
 from ghga_service_commons.utils.utc_dates import now_as_utc
 from pytest_httpx import HTTPXMock, httpx_mock  # noqa: F401
 
-from dcs.config import Config
 from dcs.core import models
-from dcs.core.data_repository import DataRepositoryConfig
-from dcs.inject import prepare_rest_app
 from dcs.ports.outbound.dao import DrsObjectDaoPort
 from tests_dcs.fixtures.joint import EXAMPLE_FILE, JointFixture, PopulatedFixture
 from tests_dcs.fixtures.mock_api.app import router
@@ -196,61 +191,3 @@ async def test_register_file_twice(populated_fixture: PopulatedFixture, caplog):
     failure_message = f"Could not register file with id '{
         example_file.file_id}' as an entry already exists for this id."
     assert failure_message in caplog.messages
-
-
-@pytest.mark.parametrize(
-    "url_validity, buffer, expected_url_max_age",
-    [(60, 10, 50), (15, 10, 10)],
-    ids=["Normal", "UseBufferAsMinimum"],
-)
-async def test_cache_headers(
-    joint_fixture: JointFixture,
-    url_validity: int,
-    buffer: int,
-    expected_url_max_age: int,
-    monkeypatch,
-):
-    """Test that the cache headers are set correctly"""
-    joint_config = joint_fixture.config.model_dump()
-    joint_config.update(
-        presigned_url_expires_after=url_validity,
-        url_expiration_buffer=buffer,
-    )
-    config = Config(**joint_config)
-    work_order_token = generate_work_order_token(
-        file_id="test-file",
-        jwk=joint_fixture.jwk,
-        valid_seconds=120,
-    )
-    headers = httpx.Headers({"Authorization": f"Bearer {work_order_token}"})
-    monkeypatch.setattr(
-        joint_fixture.data_repository,
-        "access_drs_object",
-        AsyncMock(return_value=EXAMPLE_FILE),
-    )
-    async with prepare_rest_app(
-        config=config, data_repo_override=joint_fixture.data_repository
-    ) as app:
-        async with AsyncTestClient(app) as client:
-            response = await client.get("/objects/test-file", headers=headers)
-
-        assert "Cache-Control" in response.headers
-        assert response.headers["Cache-Control"] == f"max-age={expected_url_max_age}"
-
-
-async def test_cache_param_validation():
-    """Test that the http cache-related config parameters are validated correctly"""
-    with pytest.raises(ValueError):
-        DataRepositoryConfig(
-            drs_server_uri="",
-            ekss_base_url="",
-            presigned_url_expires_after=0,
-            url_expiration_buffer=10,
-        )
-    with pytest.raises(ValueError):
-        DataRepositoryConfig(
-            drs_server_uri="",
-            ekss_base_url="",
-            presigned_url_expires_after=10,
-            url_expiration_buffer=10,
-        )

services/dcs/tests_dcs/test_typical_journey.py

@@ -139,7 +139,7 @@ async def test_happy_journey(
     assert "Cache-Control" in drs_object_response.headers
     assert (
         drs_object_response.headers["Cache-Control"]
-        == f"max-age={joint_fixture.config.presigned_url_expires_after - 5}"
+        == f"max-age={joint_fixture.config.presigned_url_expires_after}"
     )
 
     # download file bytes: