redis integration (ICDC-3031)

[erm156]

JIRA ticket: https://tracker.nci.nih.gov/browse/ICDC-3031

• not sure if redis configuration is appropriate for deployment to various tiers (redis host/port are read from environment variables)

• the graphql query is extracted from the request as a string and used as a key in the cache

• cache duration is set for 864000 seconds (10 days)

[erm156]

I'm noticing that the Redis client emits errors continuously when Redis is not available, which causes the app to become unresponsive as you mentioned above. When I try to close/shutdown the Redis client upon encountering an error (Redis unavailable), the entire app crashes. Wrapping this code in a try/catch doesn't seem to make a difference. I've seen other users documenting this error, but haven't found a solution that works for our use case. It could be config-related for the Redis client, or I might need to invoke the client differently.