512 db redis health (#686)

* catches exceptions from db/redis and provides better errors on startup

* move health endpoint changes to separate branch

* update changelog

* catch appropriate redis err, stop app upon db and cache connection failure

* adds check for cache enabled

CHANGELOG.md

@@ -41,6 +41,7 @@ The types of changes are:
 * Added the ability to delete a datastore from the frontend [#683] https://github.com/ethyca/fidesops/pull/683
 * Added the ability to disable/enable a datastore from the frontend [#693] https://github.com/ethyca/fidesops/pull/693
 * Adds Postgres and Redis health checks to health endpoint [#690](https://github.com/ethyca/fidesops/pull/690)
+* Added health checks and better error messages on app startup for both db and cache [#686](https://github.com/ethyca/fidesops/pull/686)
 
 ### Changed
 

src/fidesops/main.py

@@ -7,6 +7,7 @@
 from fastapi import FastAPI, Request, Response
 from fastapi.staticfiles import StaticFiles
 from fideslog.sdk.python.event import AnalyticsEvent
+from redis.exceptions import ResponseError
 from starlette.background import BackgroundTask
 from starlette.middleware.cors import CORSMiddleware
 
@@ -18,12 +19,13 @@
 from fidesops.api.v1.api import api_router
 from fidesops.api.v1.exception_handlers import ExceptionHandlers
 from fidesops.api.v1.urn_registry import V1_URL_PREFIX
-from fidesops.common_exceptions import FunctionalityNotConfigured
+from fidesops.common_exceptions import FunctionalityNotConfigured, RedisConnectionError
 from fidesops.core.config import config
 from fidesops.db.database import init_db
 from fidesops.schemas.analytics import Event, ExtraData
 from fidesops.tasks.scheduled.scheduler import scheduler
 from fidesops.tasks.scheduled.tasks import initiate_scheduled_request_intake
+from fidesops.util.cache import get_cache
 from fidesops.util.logger import get_fides_log_record_factory
 
 logging.basicConfig(level=config.security.LOG_LEVEL)
@@ -142,7 +144,19 @@ def start_webserver() -> None:
 
     if config.database.ENABLED:
         logger.info("Running any pending DB migrations...")
-        init_db(config.database.SQLALCHEMY_DATABASE_URI)
+        try:
+            init_db(config.database.SQLALCHEMY_DATABASE_URI)
+        except Exception as error:  # pylint: disable=broad-except
+            logger.error(f"Connection to database failed: {error}")
+            return
+
+    if config.redis.ENABLED:
+        logger.info("Running Redis connection test...")
+        try:
+            get_cache()
+        except (RedisConnectionError, ResponseError) as e:
+            logger.error(f"Connection to cache failed: {e}")
+            return
 
     scheduler.start()