[ELI-619] - switching to global caching

Author: TOEL2

poetry.lock

@@ -35,6 +35,7 @@ pyhamcrest = "^2.1.0"
 boto3 = "^1.40.57"
 botocore = "^1.40.76"
 aws-xray-sdk = "2.15.0"
+cachetools = "^7.0.1"
 
 [tool.poetry.group.dev.dependencies]
 ruff = "^0.14.10"

pyproject.toml

@@ -1,4 +1,5 @@
 from typing import Literal
+import os
 
 URL_PREFIX = "patient-check"
 RULE_STOP_DEFAULT = False
@@ -8,9 +9,4 @@
 CONSUMER_MAPPING_FILE_NAME = "consumer_mapping_config.json"
 RESERVED_TEST_CONSUMER_IDS = {"test-consumer-1", "test-consumer-2", "test-consumer-3"}
 
-TTL = {
-    "test": 300,
-    "dev": 300,
-    "preprod": 300,
-    "prod": 300,
-}
+CACHE_TTL_SECONDS = int(os.getenv("CONFIG_CACHE_TTL_SECONDS", "1800"))

src/eligibility_signposting_api/config/constants.py

@@ -7,15 +7,18 @@
 
 from aws_xray_sdk.core import xray_recorder
 from botocore.client import BaseClient
+from cachetools import TTLCache
 from wireup import Inject, service
 
 from eligibility_signposting_api.model.campaign_config import CampaignConfig, Rules
-from eligibility_signposting_api.config.constants import TTL, RESERVED_TEST_CONSUMER_IDS
+from eligibility_signposting_api.config.constants import CACHE_TTL_SECONDS, RESERVED_TEST_CONSUMER_IDS
 
 BucketName = NewType("BucketName", str)
 
 logger = logging.getLogger(__name__)
 
+campaign_config_cache: TTLCache[str, list[CampaignConfig]] = TTLCache(maxsize=1, ttl=CACHE_TTL_SECONDS)
+
 @service
 class CampaignRepo:
     """Repository class for Campaign Rules, which we can use to calculate a person's eligibility for vaccination.
@@ -30,38 +33,29 @@ def __init__(
         super().__init__()
         self.s3_client = s3_client
         self.bucket_name = bucket_name
-        self._campaign_configs_cache: list[CampaignConfig] | None = None
-        self._cache_expiry_epoch: float = 0.0
-        self._cache_ttl_seconds: int = int(TTL.get(os.getenv("ENVIRONMENT"), 0))
 
     def get_campaign_configs(self, consumer_id: str) -> Generator[CampaignConfig, None, None]:
-        now = time.time()
-        cache_enabled = self._cache_ttl_seconds > 0
-        cache_valid = (
-            cache_enabled
-            and consumer_id not in RESERVED_TEST_CONSUMER_IDS
-            and self._campaign_configs_cache is not None
-            and now < self._cache_expiry_epoch
-        )
+        bypass = consumer_id in RESERVED_TEST_CONSUMER_IDS
+        cache_key = "all_campaigns"
+        cached = None if bypass else campaign_config_cache.get(cache_key)
 
         with xray_recorder.in_subsegment("CampaignRepo.get_campaign_configs"):
-            if cache_valid:
+            if cached is not None:
                 logger.info("Using cached campaign configs")
-                yield from self._campaign_configs_cache
+                yield from cached
                 return
 
             logger.info(
                 "Refreshing campaign configs from S3 (consumer_id=%s, ttl_seconds=%s)",
                 consumer_id,
-                self._cache_ttl_seconds,
+                CACHE_TTL_SECONDS,
             )
-            campaign_configs = self._load_campaign_configs_from_s3()
+            configs = self._load_campaign_configs_from_s3()
 
-            if cache_enabled and consumer_id not in RESERVED_TEST_CONSUMER_IDS:
-                self._campaign_configs_cache = campaign_configs
-                self._cache_expiry_epoch = now + self._cache_ttl_seconds
+            if not bypass:
+                campaign_config_cache[cache_key] = configs
 
-            yield from campaign_configs
+            yield from configs
 
     def _load_campaign_configs_from_s3(self) -> list[CampaignConfig]:
         campaign_configs: list[CampaignConfig] = []

src/eligibility_signposting_api/repos/campaign_repo.py

@@ -33,7 +33,7 @@
 from eligibility_signposting_api.model.consumer_mapping import ConsumerCampaign, ConsumerId, ConsumerMapping
 from eligibility_signposting_api.processors.hashing_service import HashingService, HashSecretName
 from eligibility_signposting_api.repos import SecretRepo
-from eligibility_signposting_api.repos.campaign_repo import BucketName
+from eligibility_signposting_api.repos.campaign_repo import BucketName, campaign_config_cache
 from eligibility_signposting_api.repos.person_repo import TableName
 from tests.fixtures.builders.model import rule
 from tests.fixtures.builders.model.rule import RulesMapperFactory
@@ -103,6 +103,10 @@ def moto_server(request: pytest.FixtureRequest) -> URL:
     return url
 
 
+@pytest.fixture(autouse=True)
+def clear_cache():
+    campaign_config_cache.clear()
+
 def is_responsive(url: URL) -> bool:
     try:
         response = httpx.get(str(url))

tests/integration/conftest.py

@@ -4,7 +4,7 @@
 
 import pytest
 
-from eligibility_signposting_api.repos.campaign_repo import CampaignRepo, BucketName
+from eligibility_signposting_api.repos.campaign_repo import CampaignRepo, BucketName, campaign_config_cache
 from tests.fixtures.builders.model.rule import CampaignConfigFactory
 
 
@@ -13,6 +13,10 @@ def make_s3_body(payload: dict):
 
 
 class TestCampaignRepo:
+    @pytest.fixture(autouse=True)
+    def clear_cache(self):
+        campaign_config_cache.clear()
+
     @pytest.fixture
     def mock_s3_client(self):
         return MagicMock()