Adding async redis caching

[mattyweb]

First version with Redis caching

• including aiocache library
• using Pickle serialization
• adding Redis container
• added some tests
• added faster requests loader script
• redid map/clusters
• created stubs for other legacy routes

[mattyweb]

Other than the map essentials, shim routes are placeholders:

• open-requests
• map/pins
• visualizations
• comparison/frequency
• comparison/timetoclose
• comparison/counts
• feedback

Needs infrastructure to be "productionized" (e.g. Redis, Gunicorn)

Needs data loading

[mattyweb]

Need to keep tweaking Redis behavior

Will see "Connection <RedisConnection [db:0]> has pending commands, closing it." messages if new requests come in before the previous one has finished.

As a result may see "Redis set cache timeout error" or

Ignore set errors, and do a CACHE_MAX_RETRIES attempts to get the cache.

This sometimes will results in a loop which will return a 429 HTTP error. These errors show up in client.

Need to tweak max retries, cache timeout, pool size, cache eviction policy and cache max memory size.

Also, might want to revisit whether JSON serialization is better than Pickle...

[mattyweb]

OK. Also added Sentry using the ASGI extension. Problem with the free account is it's single-user, but we could create a shared account. Biggest value would be setting up alerts that go to Slack.

[mattyweb]

now works with the version 2 UI
the shim now supports the map/pins and open-requests endpoints