community[minor]: llamafile embeddings support (#17976)

* **Description:** adds `LlamafileEmbeddings` class implementation for
generating embeddings using
[llamafile](https://github.com/Mozilla-Ocho/llamafile)-based models.
Includes related unit tests and notebook showing example usage.
* **Issue:** N/A
* **Dependencies:** N/A

docs/docs/integrations/text_embedding/llamafile.ipynb

@@ -0,0 +1,157 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "278b6c63",
+   "metadata": {},
+   "source": [
+    "# llamafile\n",
+    "\n",
+    "Let's load the [llamafile](https://github.com/Mozilla-Ocho/llamafile) Embeddings class.\n",
+    "\n",
+    "## Setup\n",
+    "\n",
+    "First, the are 3 setup steps:\n",
+    "\n",
+    "1. Download a llamafile. In this notebook, we use `TinyLlama-1.1B-Chat-v1.0.Q5_K_M` but there are many others available on [HuggingFace](https://huggingface.co/models?other=llamafile).\n",
+    "2. Make the llamafile executable.\n",
+    "3. Start the llamafile in server mode.\n",
+    "\n",
+    "You can run the following bash script to do all this:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "43ef6dfa-9cc4-4552-8a53-5df523afae7c",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "%%bash\n",
+    "# llamafile setup\n",
+    "\n",
+    "# Step 1: Download a llamafile. The download may take several minutes.\n",
+    "wget -nv -nc https://huggingface.co/jartine/TinyLlama-1.1B-Chat-v1.0-GGUF/resolve/main/TinyLlama-1.1B-Chat-v1.0.Q5_K_M.llamafile\n",
+    "\n",
+    "# Step 2: Make the llamafile executable. Note: if you're on Windows, just append '.exe' to the filename.\n",
+    "chmod +x TinyLlama-1.1B-Chat-v1.0.Q5_K_M.llamafile\n",
+    "\n",
+    "# Step 3: Start llamafile server in background. All the server logs will be written to 'tinyllama.log'.\n",
+    "# Alternatively, you can just open a separate terminal outside this notebook and run: \n",
+    "#   ./TinyLlama-1.1B-Chat-v1.0.Q5_K_M.llamafile --server --nobrowser --embedding\n",
+    "./TinyLlama-1.1B-Chat-v1.0.Q5_K_M.llamafile --server --nobrowser --embedding > tinyllama.log 2>&1 &\n",
+    "pid=$!\n",
+    "echo \"${pid}\" > .llamafile_pid  # write the process pid to a file so we can terminate the server later"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "3188b22f-879f-47b3-9a27-24412f6fad5f",
+   "metadata": {},
+   "source": [
+    "## Embedding texts using LlamafileEmbeddings\n",
+    "\n",
+    "Now, we can use the `LlamafileEmbeddings` class to interact with the llamafile server that's currently serving our TinyLlama model at http://localhost:8080."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "0be1af71",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain_community.embeddings import LlamafileEmbeddings"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "2c66e5da",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "embedder = LlamafileEmbeddings()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "01370375",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "text = \"This is a test document.\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "a42e4035",
+   "metadata": {},
+   "source": [
+    "To generate embeddings, you can either query an invidivual text, or you can query a list of texts."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "91bc875d-829b-4c3d-8e6f-fc2dda30a3bd",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "query_result = embedder.embed_query(text)\n",
+    "query_result[:5]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "a4b0d49e-0c73-44b6-aed5-5b426564e085",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "doc_result = embedder.embed_documents([text])\n",
+    "doc_result[0][:5]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "1ccc78fc-03ae-411d-ae73-74a4ee91c725",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "%%bash\n",
+    "# cleanup: kill the llamafile server process\n",
+    "kill $(cat .llamafile_pid)\n",
+    "rm .llamafile_pid"
+   ]
+  }
+ ],
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+   "mimetype": "text/x-python",
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+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.11.7"
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+  "vscode": {
+   "interpreter": {
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+ "nbformat_minor": 5
+}