MCP Base

server
utils
// Ollama Embeddings Service
// This service provides embeddings generated by Ollama running locally

import fetch from "node-fetch";

/**
 * Options for the Ollama embeddings service
 */
interface OllamaEmbeddingsOptions {
  baseUrl?: string;
  model?: string;
}

/**
 * Service for generating embeddings using a local Ollama instance
 */
class OllamaEmbeddingsService {
  baseUrl: string;
  model: string;

  /**
   * Create a new Ollama embeddings service
   * @param {OllamaEmbeddingsOptions} options Configuration options
   */
  constructor(options: OllamaEmbeddingsOptions = {}) {
    this.baseUrl =
      options.baseUrl || process.env.OLLAMA_URL || "http://localhost:11434";
    this.model = options.model || process.env.OLLAMA_EMBED_MODEL || "nomic-embed-text";

    console.log(
      `Initialized Ollama embeddings service with model ${this.model}`
    );
  }

  /**
   * Generate embeddings for the given text
   * @param {string} text The text to generate embeddings for
   * @returns {Promise<number[]>} A promise that resolves to the embedding vector
   */
  async generateEmbedding(text: string): Promise<number[]> {
    try {
      const response = await fetch(`${this.baseUrl}/api/embeddings`, {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
        },
        body: JSON.stringify({
          model: this.model,
          prompt: text,
          options: {
            dimensions: 768, // Using 768 dimensions (more efficient than 1536)
          },
        }),
      });

      if (!response.ok) {
        const errorText = await response.text();
        throw new Error(
          `Ollama embeddings API error (${response.status}): ${errorText}`
        );
      }

      const data = await response.json();
      return data.embedding;
    } catch (error) {
      console.error("Error generating embeddings with Ollama:", error);
      throw new Error(`Failed to generate embeddings: ${error.message}`);
    }
  }

  /**
   * Generate embeddings for multiple texts in batch
   * @param {string[]} texts Array of texts to generate embeddings for
   * @returns {Promise<number[][]>} A promise that resolves to an array of embedding vectors
   */
  async generateBatchEmbeddings(texts: string[]): Promise<number[][]> {
    try {
      // Ollama doesn't have a batch API, so we'll process sequentially
      const embeddings: number[][] = [];

      for (const text of texts) {
        const embedding = await this.generateEmbedding(text);
        embeddings.push(embedding);
      }

      return embeddings;
    } catch (error) {
      console.error("Error generating batch embeddings with Ollama:", error);
      throw new Error(`Failed to generate batch embeddings: ${error.message}`);
    }
  }

  /**
   * Check if the Ollama service is available
   * @returns {Promise<boolean>} A promise that resolves to true if the service is available
   */
  async isAvailable(): Promise<boolean> {
    try {
      const response = await fetch(`${this.baseUrl}/api/tags`);
      return response.ok;
    } catch (error) {
      console.error("Error checking Ollama availability:", error);
      return false;
    }
  }

  /**
   * Check if the specified model is available in Ollama
   * @returns {Promise<boolean>} A promise that resolves to true if the model is available
   */
  async isModelAvailable(): Promise<boolean> {
    try {
      const response = await fetch(`${this.baseUrl}/api/tags`);

      if (!response.ok) {
        return false;
      }

      const data = await response.json();
      // The API returns the model name with a tag, e.g. "nomic-embed-text:latest"
      return data.models.some((model: { name: string }) =>
        model.name.startsWith(this.model)
      );
    } catch (error) {
      console.error("Error checking model availability:", error);
      return false;
    }
  }

  /**
   * Pull the embedding model if not already available
   * @returns {Promise<boolean>} A promise that resolves to true if successful
   */
  async pullModelIfNeeded(): Promise<boolean> {
    const isAvailable = await this.isModelAvailable();

    if (isAvailable) {
      console.log(`Model ${this.model} is already available`);
      return true;
    }

    try {
      console.log(`Pulling model ${this.model}...`);

      const response = await fetch(`${this.baseUrl}/api/pull`, {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
        },
        body: JSON.stringify({
          stream: false,
          name: this.model,
        }),
      });

      if (!response.ok) {
        const errorText = await response.text();
        throw new Error(`Failed to pull model: ${errorText}`);
      }
      console.log(`Successfully pulled model ${this.model}`);
      return true;
    } catch (error) {
      console.error("Error pulling model:", error);
      return false;
    }
  }
}

export default OllamaEmbeddingsService;