[ENH] Nomic Text Embed function

[andrewblum]

Description of changes

Summarize the changes made by this PR.

• New functionality
  • Embedding function that calls the Nomic Atlas API asked for by @tazarov in [Feature Request]: Nomic Embed EF #2061

Test plan

How are these changes tested?
Added a test that is similar to the existing test for Ollama.

• Tests pass locally with pytest for python, yarn test for js, cargo test for rust

Documentation Changes

Are all docstrings for user-facing APIs updated if required? Do we need to make documentation changes in the docs repository?

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Name	Status	Preview	Comments	Updated (UTC)
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[github-actions]

Reviewer Checklist

Please leverage this checklist to ensure your code review is thorough before approving

Testing, Bugs, Errors, Logs, Documentation

• Can you think of any use case in which the code does not behave as intended? Have they been tested?
• Can you think of any inputs or external events that could break the code? Is user input validated and safe? Have they been tested?
• If appropriate, are there adequate property based tests?
• If appropriate, are there adequate unit tests?
• Should any logging, debugging, tracing information be added or removed?
• Are error messages user-friendly?
• Have all documentation changes needed been made?
• Have all non-obvious changes been commented?

System Compatibility

• Are there any potential impacts on other parts of the system or backward compatibility?
• Does this change intersect with any items on our roadmap, and if so, is there a plan for fitting them together?

Quality

• Is this code of a unexpectedly high quality (Readability, Modularity, Intuitiveness)

[andrewblum]

Note -- Nomic has a python SDK we could also use to do this but it just hits the same API so didn't seem worth adding a dependency just to hit 1 endpoint.

[tazarov]

Almost there. We need a tiny bit more error handling and a couple more tests.

[tazarov]

What is the limit to the maximum number of texts that can be sent at once? If there's a limit, let's implement it on the client side so we don't do the round trip to raise an error.

Important: Do not add any loop logic here. If a chunk fails, throw an exception and let users implement their own chunking and subsequent error handling.

[andrewblum]

Nomic responded:
"Yes, you will get rate limited with 429s if you hit it too fast (in practice this shouldn't happen unless you are a bot trying to DOS the API).

You can send as many as you'd like per request, they will get processed in parallel. It's recommended you break it up yourself into several requests or use the Nomic python client because you will see network latency due to the large request/response size if you send dozens of megabytes of text in a single request"

[tazarov]

Let's leave it as-is for now. We have some ideas that we're trying to develop to make error handling a little bit more consistent across all EFs.

[tazarov]

Add some error checking in case the API returns an error. You can also use resp.raise_for_status() to raise if the status is not 2xx.

Without error checking we'll raise KeyError as the response may not contain embeddings key.

[tazarov]

I know this has been used in the past but let's add an annotation instead - @pytest.mark.skipif("NOMIC_API_KEY" not in os.environ, reason="NOMIC_API_KEY not set, skipping test.")

Decorators are implicit flow control, but this is a common practice for pytest so we might as well use it.

[tazarov]

Let's add couple of negative test cases:

• Empty API key
• Error response (mock server)
• Too many texts

For the mock server:

pip install pytest_httpserver>=1.0.10

import pytest
from pytest_httpserver import HTTPServer
import json
from unittest.mock import patch

with HTTPServer() as httpserver:
    # Define the response
    httpserver.expect_oneshot_request("/embeddings/text",method="POST").respond_with_data(
        json.dumps({"error": "some error message"}), # adjust to fit Nomic API response
        status=400,
        
    )
    with patch.object(NomicEmbeddingFunction, '_api_url', f"http://{httpserver.host}:{httpserver.port}/embeddings/text",):
        nomic_instance = NomicEmbeddingFunction()
        with pytest.raises(Exception):
            nomic_instance(["test text"])

[andrewblum]

Added these tests as well as one for missing model name, but did not include the "too many texts" test. Nomic responded saying:

• "You can send as many as you'd like per request, they will get processed in parallel. It's recommended you break it up yourself into several requests or use the Nomic python client because you will see network latency due to the large request/response size if you send dozens of megabytes of text in a single request"

So I am not sure 1) what we want to consider too large 2) best way to check for that 3) if you still want this

[andrewblum]

Also -- should I add pytest_httpserver to the projects requirements_dev file and check it in as part of this PR?

[tazarov]

Yes, please add it to the requirements_dev.

We do have a limitation in Chroma API regarding the maximum number of embeddings, but we generally don't tie that to the embeddings functions batch size. So you can leave it as is for now.

[tazarov]

Looks good. Just a couple of minor nits, and this should be ready to go.

[tazarov]

Yes, please add it to the requirements_dev.

We do have a limitation in Chroma API regarding the maximum number of embeddings, but we generally don't tie that to the embeddings functions batch size. So you can leave it as is for now.

[tazarov]

Let's leave it as-is for now. We have some ideas that we're trying to develop to make error handling a little bit more consistent across all EFs.

[tazarov]

I think we can remove the decorator here, as this is a negative test. It is supposed to fail regardless of whether we're testing with the Nomic API key or not.

[tazarov]

Maybe also remove this decorator and let the test run, as this is a local mock test.

I think it makes sense to add some sort of activation flags (other than API keys) for EF testing, but this requires further consideration.

[tazarov]

Looks good. Thank you @andrewblum.

[andrewblum]

Linting issue with the requirements_dev.txt file, should be fixed now. I didn't see it because I had been running --no-verify due to the pre-commit hook returning a ton of mypy errors on code I hadn't touched in embedding_functions.py Did the linting settings get changed since the last time someone ran it against that file?

[tazarov]

@andrewblum, the linter runs this which you can also execute locally to check:

pre-commit run --all-files trailing-whitespace 
pre-commit run --all-files mixed-line-ending
pre-commit run --all-files end-of-file-fixer
pre-commit run --all-files requirements-txt-fixer
pre-commit run --all-files check-xml
pre-commit run --all-files check-merge-conflict
pre-commit run --all-files check-case-conflict
pre-commit run --all-files check-docstring-first
pre-commit run --all-files black
pre-commit run --all-files flake8
pre-commit run --all-files prettier
pre-commit run --all-files check-yaml

[andrewblum]

Thanks for that, those return all green for me locally so it should be good to re-run.

[tazarov]

👍