feat: make ioredis configurable via environment variables (#3365)

* feat: expose ioredis client options

* run linter

* refactor redis client init into class extension

* explicitly handle constructor errors

* rename singletons

.env.sample

@@ -16,7 +16,15 @@ DATABASE_CONNECTION_POOL_MIN=
 DATABASE_CONNECTION_POOL_MAX=
 # Uncomment this to disable SSL for connecting to Postgres
 # PGSSLMODE=disable
-REDIS_URL=redis://localhost:6379
+
+# For redis you can either specify an ioredis compatible url like this
+REDIS_URL=redis://localhost:6479
+# or alternatively, if you would like to provide addtional connection options,
+# use a base64 encoded JSON connection option object. Refer to the ioredis documentation
+# for a list of available options.
+# Example: Use Redis Sentinel for high availability
+# {"sentinels":[{"host":"sentinel-0","port":26379},{"host":"sentinel-1","port":26379}],"name":"mymaster"}
+# REDIS_URL=ioredis://eyJzZW50aW5lbHMiOlt7Imhvc3QiOiJzZW50aW5lbC0wIiwicG9ydCI6MjYzNzl9LHsiaG9zdCI6InNlbnRpbmVsLTEiLCJwb3J0IjoyNjM3OX1dLCJuYW1lIjoibXltYXN0ZXIifQ==
 
 # URL should point to the fully qualified, publicly accessible URL. If using a
 # proxy the port in URL and PORT may be different.