Remote patron activity sync celery task (PP-1164) (#1894)

This PR updates our Patron API that sync with remote providers to do the sync as an async celery task, rather then in the main web thread worker. To coordinate these patron activity sync tasks, I wired up redis as a service that we can use to store data, not just as a celery broker.

Redis is used to store the state of the patron activity sync and as a distributed lock, so that only one task is doing a sync at a time.

README.md

@@ -146,7 +146,7 @@ grant all privileges on database circ to palace;
 
 ### Redis
 
-Redis is used as the broker for Celery. You can run Redis with docker using the following command:
+Redis is used as the broker for Celery and the caching layer. You can run Redis with docker using the following command:
 
 ```sh
 docker run -d --name redis -p 6379:6379 redis
@@ -193,6 +193,19 @@ We support overriding a number of other Celery settings via environment variable
 the defaults should be sufficient. The full list of settings can be found in
 [`service/celery/configuration.py`](src/palace/manager/service/celery/configuration.py).
 
+#### Redis
+
+We use Redis as the caching layer for the application. Although you can use the same redis database for both
+Celery and caching, we recommend that you use a separate database for each purpose to avoid conflicts.
+
+- `PALACE_REDIS_URL`: The URL of the Redis instance to use for caching. (**required**).
+    - for example:
+        ```sh
+          export PALACE_REDIS_URL="redis://localhost:6379/1"
+        ```
+- `PALACE_REDIS_KEY_PREFIX`: The prefix to use for keys stored in the Redis instance. The default is `palace`.
+    This is useful if you want to use the same Redis database for multiple CM (optional).
+
 #### General
 
 - `PALACE_BASE_URL`: The base URL of the application. Used to create absolute links. (optional)

docker-compose.yml

@@ -20,13 +20,15 @@ x-cm-variables: &cm
     PALACE_CELERY_BROKER_URL: "redis://redis:6379/0"
     PALACE_CELERY_BROKER_TRANSPORT_OPTIONS_GLOBAL_KEYPREFIX: "test"
     PALACE_CELERY_CLOUDWATCH_STATISTICS_DRYRUN: "true"
+    PALACE_REDIS_URL: "redis://redis:6379/1"
 
     # Set up the environment variables used for testing as well
     PALACE_TEST_DATABASE_URL: "postgresql://palace:test@pg:5432/circ"
     PALACE_TEST_SEARCH_URL: "http://os:9200"
     PALACE_TEST_MINIO_URL: "http://minio:9000"
     PALACE_TEST_MINIO_USER: "palace"
     PALACE_TEST_MINIO_PASSWORD: "test123456789"
+    PALACE_TEST_REDIS_URL: "redis://redis:6379/2"
   depends_on:
     pg:
       condition: service_healthy

pyproject.toml

@@ -263,6 +263,7 @@ python-dateutil = "2.9.0.post0"
 python3-saml = "^1.16"  # python-saml is required for SAML authentication
 pytz = "^2023.3"
 pyyaml = "^6.0"
+redis = "^5.0.5"
 redmail = "^0.6.0"
 requests = "^2.29"
 sqlalchemy = {version = "^1.4", extras = ["mypy"]}
@@ -308,6 +309,7 @@ types-Pillow = "^10.0.0"
 types-psycopg2 = "^2.9.21"
 types-python-dateutil = "^2.8.19"
 types-pytz = "^2024.1"
+types-redis = "^4.6.0.20240425"
 types-requests = "^2.28.11"
 
 [tool.poetry.group.pg]