feat: Add /write-to-online-store method to the python feature server

[tpvasconcelos]

This PR adds a /write-to-online-store HTTP POST method to the python feature server.

Example: using curl to push fresh feature vectors to the online store:

curl -X POST "http://localhost:6566/write-to-online-store" -d '{
    "feature_view_name": "driver_hourly_stats",
    "df": {
            "driver_id": [1001],
            "event_timestamp": ["2022-05-13 10:59:42"],
            "created": ["2022-05-13 10:59:42"],
            "conv_rate": [1.0],
            "acc_rate": [1.0],
            "avg_daily_trips": [1000]
    }
  }'

Check the table below for the output difference of the /get-online-features before and after the operation above:

$ curl -X POST "http://localhost:6566/get-online-features" -d '{
    "features": [
      "driver_hourly_stats:conv_rate",
      "driver_hourly_stats:acc_rate",
      "driver_hourly_stats:avg_daily_trips"
    ],
    "entities": {
      "driver_id": [1001]
    }
  }' | jq

Before:	After:
{ "metadata": { "feature_names": [ "driver_id", "avg_daily_trips", "conv_rate", "acc_rate" ] }, "results": [ { "values": [ 1001, 3, 0.15759889781475067, 0.5574429631233215 ], "statuses": [...], "event_timestamps": [ "1970-01-01T00:00:00Z", "2022-02-04T10:00:00Z", "2022-02-04T10:00:00Z", "2022-02-04T10:00:00Z" ] } ] }	{ "metadata": { "feature_names": [ "driver_id", "avg_daily_trips", "conv_rate", "acc_rate" ] }, "results": [ { "values": [ 1001, 1000, 1, 1 ], "statuses": [...], "event_timestamps": [ "1970-01-01T00:00:00Z", "2022-05-13T10:59:42Z", "2022-05-13T10:59:42Z", "2022-05-13T10:59:42Z" ] } ] }

Signed-off-by: Tomas Pereira de Vasconcelos tomasvasconcelos1@gmail.com
@tpvasconcelos

[tpvasconcelos]

@adchia I used the same naming convention as in store.write_to_online_store() for the endpoint name and JSON fields. WDYT?

[codecov-commenter]

Codecov Report

Merging #2423 (a2c3cc9) into master (37971a4) will decrease coverage by 0.02%.
The diff coverage is 44.44%.

@@            Coverage Diff             @@
##           master    #2423      +/-   ##
==========================================
- Coverage   58.62%   58.60%   -0.03%     
==========================================
  Files         126      126              
  Lines       10850    10868      +18     
==========================================
+ Hits         6361     6369       +8     
- Misses       4489     4499      +10     

Flag	Coverage Δ
unittests	58.60% <44.44%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
sdk/python/feast/feature_server.py	35.18% <44.44%> (+4.62%)	⬆️

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[adchia]

@adchia I used the same naming convention as in store.write_to_online_store() for the endpoint name and JSON fields. WDYT?

Hey! Can you actually use the store.push() method instead for this and rename accordingly? Reason why we wanted the name to be a little more general is we'll likely also want to support in the future pushing to the offline store too.

I'll add a warning on the existing write_to_online_store() method in favor of the push() method.

Also: you still have linter issues

[tpvasconcelos]

Hey! Can you actually use the store.push() method instead for this and rename accordingly? Reason why we wanted the name to be a little more general is we'll likely also want to support in the future pushing to the offline store too.

@adchia Will this method allow to only push to the online store? As I understand, the future goal of this method is to push to both the online and offline stores with a single call right? I would prefer still having an option to only push to the online store. If this is the case, should I just add the /push method instead of removing the /write-to-online-store one?

[adchia]

I think that's fine for now as long as both of those methods have an alpha warning attached to the methods.

I think the .push method should probably allow flexibility in pushing to offline or online or both. Today it only pushes to the online store for feature views that depend on a PushSource.

Down the road, one example way of allowing pushing to offline stores might be having a boolean flag that lets you configure pushing to the batch source. e.g.

click_event_source = PushSource(
    name="click_event_source",
    schema=[
       ...
    ],
    batch_source=BigQuerySource(
			table="my_project.my_Dataset.click_event_table"
		),
    push_to_batch=True # will now also create or append to the batch source.
)

And this way, you can have a stream based FeatureView depend on a Union[PushSource, KafkaSource, KinesisSource] etc.

[adchia]

/lgtm

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