Ollama embedding - Changed localhost to 127.0.0.1

[paulwongx]

Link to discussion

1. Updates numThreads to numThread in the docs to use the API correctly ref
2. Adds a function in the OllamaEmbeddings class to fetch 127.0.0.1 if user puts localhost to work out of the box with node's fetch since it default resolves to ipv6 (::1) which Ollama server isn't listening to. Now it works out of the box. Issue is related to node's native fetch command not working when fetching localhost that isn't listening on the ipv6 localhost address but the ipv4 localhost address of 127.0.0.1 as per this. The function is copied over from the Ollama class implementation. No change in the docs otherwise.

Fixes # (issue)

[dosubot]

This PR adds a new fetch request using the fetch function, with a modified base URL to handle a specific issue with Node 18 and resolving "localhost". Please review this change to ensure it aligns with the project's requirements and best practices.

[jacoblee93]

Just to reduce the amount of magic, can we do something like this and change the default in the constructor instead?

https://github.com/langchain-ai/langchainjs/blob/main/langchain/src/chat_models/ollama.ts#L35

[paulwongx]

I was about to change the baseUrl to 127.0.0.1 but after looking through the rest of the Ollama code, I realized that all the other Ollama functions like ChatOllama and Ollama class call on this createOllamaStream which has this reformatting logic

  let formattedBaseUrl = baseUrl;
  if (formattedBaseUrl.startsWith("http://localhost:")) {
    // Node 18 has issues with resolving "localhost"
    // See https://github.com/node-fetch/node-fetch/issues/1624
    formattedBaseUrl = formattedBaseUrl.replace(
      "http://localhost:",
      "http://127.0.0.1:"
    );
  }

Source

I thought this was more appropriate for the following reasons:

1. The default baseUrl across Ollama classes can be consitently localhost. The docs showing examples are consistent too in terms of showing the default baseUrl in the config object as localhost instead of 127.0.0.1.
2. The end user won't mess it up if they override the default baseUrl with http://localhost/.... either. Compared to if we change the baseUrl to 127.0.0.1, and the user overrides with localhost and it doesn't work, they'll raise an issue on the repo. Having this function avoids potential future issues.

Either way, once you confirm either approach, I'll make the PR. If as-is, this PR should be okay.

[jacoblee93]

Ah you're right, let's leave it your way then!

[jacoblee93]

Small comment

[jacoblee93]

Thank you!