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Support Redis Sentinel database connections (#5196)

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# Support Redis Sentinel database connections

This PR adds the support to connect not only to Redis standalone servers
but High Availability Replication sets too
(https://redis.io/docs/management/sentinel/)
Redis Replica Sets have on Master allowing to write data and 2+ replicas
with read-only access to the data. The additional Redis Sentinel
instances monitor all server and reconfigure the RW-Master on the fly if
it comes unavailable.

Therefore all connections must be made through the Sentinels the query
the current master for a read-write connection. This PR adds basic
support to also allow a redis connection url specifying a Sentinel as
Redis connection.

Redis documentation and Jupyter notebook with Redis examples are updated
to mention how to connect to a redis Replica Set with Sentinels

        - 

Remark - i did not found test cases for Redis server connections to add
new cases here. Therefor i tests the new utility class locally with
different kind of setups to make sure different connection urls are
working as expected. But no test case here as part of this PR.
This commit is contained in:
sseide
2023-07-17 16:18:51 +02:00
committed by GitHub
parent 2e47412073
commit 25e3d3f283
6 changed files with 268 additions and 30 deletions
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30
docs/extras/ecosystem/integrations/redis.mdx
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@@ -8,6 +8,36 @@ It is broken into two parts: installation and setup, and then references to spec
## Wrappers
All wrappers needing a redis url connection string to connect to the database support either a stand alone Redis server
or a High-Availability setup with Replication and Redis Sentinels.
### Redis Standalone connection url
For standalone Redis server the official redis connection url formats can be used as describe in the python redis modules
"from_url()" method [Redis.from_url](https://redis-py.readthedocs.io/en/stable/connections.html#redis.Redis.from_url)
Example: `redis_url = "redis://:secret-pass@localhost:6379/0"`
### Redis Sentinel connection url
For [Redis sentinel setups](https://redis.io/docs/management/sentinel/) the connection scheme is "redis+sentinel".
This is an un-offical extensions to the official IANA registered protocol schemes as long as there is no connection url
for Sentinels available.
Example: `redis_url = "redis+sentinel://:secret-pass@sentinel-host:26379/mymaster/0"`
The format is `redis+sentinel://[[username]:[password]]@[host-or-ip]:[port]/[service-name]/[db-number]`
with the default values of "service-name = mymaster" and "db-number = 0" if not set explicit.
The service-name is the redis server monitoring group name as configured within the Sentinel.
The current url format limits the connection string to one sentinel host only (no list can be given) and
booth Redis server and sentinel must have the same password set (if used).
### Redis Cluster connection url
Redis cluster is not supported right now for all methods requiring a "redis_url" parameter.
The only way to use a Redis Cluster is with LangChain classes accepting a preconfigured Redis client like `RedisCache`
(example below).
### Cache
The Cache wrapper allows for [Redis](https://redis.io) to be used as a remote, low-latency, in-memory cache for LLM prompts and responses.