docs: Add Dragonfly as an online-store option to Feast Readme and docs

README.md

@@ -175,6 +175,7 @@ The list below contains the functionality that contributors are planning to deve
   * [x] [Datastore](https://docs.feast.dev/reference/online-stores/datastore)
   * [x] [Bigtable](https://docs.feast.dev/reference/online-stores/bigtable)
   * [x] [SQLite](https://docs.feast.dev/reference/online-stores/sqlite)
+  * [x] [Dragonfly](https://docs.feast.dev/reference/online-stores/dragonfly)
   * [x] [Azure Cache for Redis (community plugin)](https://github.com/Azure/feast-azure)
   * [x] [Postgres (contrib plugin)](https://docs.feast.dev/reference/online-stores/postgres)
   * [x] [Cassandra / AstraDB (contrib plugin)](https://docs.feast.dev/reference/online-stores/cassandra)

docs/reference/online-stores/dragonfly.md

@@ -0,0 +1,90 @@
+# Dragonfly online store
+
+## Description
+
+[Dragonfly](https://github.com/dragonflydb/dragonfly) is a modern in-memory datastore that implements novel algorithms and data structures on top of a multi-threaded, share-nothing architecture. Thanks to its API compatibility, Dragonfly can act as a drop-in replacement for Redis. Due to Dragonfly's hardware efficiency, you can run a single node instance on a small 8GB instance or scale vertically to large 768GB machines with 64 cores. This greatly reduces infrastructure costs as well as architectural complexity.
+
+Similar to Redis, Dragonfly can be used as an online feature store for Feast.
+
+## Using Dragonfly as a drop-in Feast online store instead of Redis
+
+Make sure you have Python and `pip` installed.
+
+Install the Feast SDK and CLI
+
+`pip install feast`
+
+In order to use Dragonfly as the online store, you'll need to install the redis extra:
+
+`pip install 'feast[redis]'`
+
+### 1. Create a feature repository
+
+Bootstrap a new feature repository:
+
+```
+feast init feast_dragonfly
+cd feast_dragonfly/feature_repo
+```
+
+Update `feature_repo/feature_store.yaml` with the below contents:
+
+```
+project: feast_dragonfly
+registry: data/registry.db
+provider: local
+online_store:
+type: redis
+connection_string: "localhost:6379"
+```
+
+### 2. Start Dragonfly
+
+There are several options available to get Dragonfly up and running quickly. We will be using Docker for this tutorial.
+
+`docker run --network=host --ulimit memlock=-1 docker.dragonflydb.io/dragonflydb/dragonfly`
+
+### 3. Register feature definitions and deploy your feature store
+
+`feast apply`
+
+The `apply` command scans python files in the current directory (`example_repo.py` in this case) for feature view/entity definitions, registers the objects, and deploys infrastructure.
+You should see the following output:
+
+```
+....
+Created entity driver
+Created feature view driver_hourly_stats_fresh
+Created feature view driver_hourly_stats
+Created on demand feature view transformed_conv_rate
+Created on demand feature view transformed_conv_rate_fresh
+Created feature service driver_activity_v1
+Created feature service driver_activity_v3
+Created feature service driver_activity_v2
+```
+
+## Functionality Matrix
+
+The set of functionality supported by online stores is described in detail [here](overview.md#functionality).
+Below is a matrix indicating which functionality is supported by the Redis online store.
+
+|                                                           | Redis |
+| :-------------------------------------------------------- | :---- |
+| write feature values to the online store                  | yes   |
+| read feature values from the online store                 | yes   |
+| update infrastructure (e.g. tables) in the online store   | yes   |
+| teardown infrastructure (e.g. tables) in the online store | yes   |
+| generate a plan of infrastructure changes                 | no    |
+| support for on-demand transforms                          | yes   |
+| readable by Python SDK                                    | yes   |
+| readable by Java                                          | yes   |
+| readable by Go                                            | yes   |
+| support for entityless feature views                      | yes   |
+| support for concurrent writing to the same key            | yes   |
+| support for ttl (time to live) at retrieval               | yes   |
+| support for deleting expired data                         | yes   |
+| collocated by feature view                                | no    |
+| collocated by feature service                             | no    |
+| collocated by entity key                                  | yes   |
+
+To compare this set of functionality against other online stores, please see the full [functionality matrix](overview.md#functionality-matrix).

docs/roadmap.md

@@ -33,6 +33,7 @@ The list below contains the functionality that contributors are planning to deve
   * [x] [Datastore](https://docs.feast.dev/reference/online-stores/datastore)
   * [x] [Bigtable](https://docs.feast.dev/reference/online-stores/bigtable)
   * [x] [SQLite](https://docs.feast.dev/reference/online-stores/sqlite)
+  * [x] [Dragonfly](https://docs.feast.dev/reference/online-stores/dragonfly)
   * [x] [Azure Cache for Redis (community plugin)](https://github.com/Azure/feast-azure)
   * [x] [Postgres (contrib plugin)](https://docs.feast.dev/reference/online-stores/postgres)
   * [x] [Cassandra / AstraDB (contrib plugin)](https://docs.feast.dev/reference/online-stores/cassandra)