Learn LangChain & LangGraph

Ref. https://langchain-ai.github.io/langgraph/tutorials/

Prerequisites

Environment Variables

Prepare .env file:

# 3rd-party frameworks
OPENAI_API_KEY=
TAVILY_API_KEY=tvly-dev-xdfFV...IYgM2
LOGFIRE_API_KEY=pylf_v1_us_z79J9...VN7Rz
LANGCHAIN_API_KEY=

# bedrock
AWS_BEDROCK_REGION=
AWS_BEDROCK_ACCESS_KEY=
AWS_BEDROCK_SECRET_KEY=

# feature flags
ENABLE_FEATURE_TAVILY=0
ENABLE_FEATURE_HUMAN_ASSISTANCE=0
ENABLE_FEATURE_MATH=0

Package Management

Install uv.

Ollama

Let's provide Ollama via http://localhost:11434/.

MCP Server

Serve some MCP's tool, ex. weather.

You need to serve some MCP server before testing langgraph:

uv run weather.py

Currently I'm listening MCP server via port number 7300 in langgraph. So don't forget set it in MCP server too.

Usage

Linux or macOS

uv venv

# WinOS: active venv
.\.venv\Scripts\activate.ps1

# Linux: active venv
source .venv/bin/activate

# Install dependency
uv sync

WindowsOS

To prevent onnxruntime incompatible with windows platform:

error: Distribution `onnxruntime==1.22.0 @ registry+https://pypi.org/simple` can't be installed because it doesn't have a source distribution or wheel for the current platform

hint: You're on Windows (`win_amd64`), but `onnxruntime` (v1.22.0) only has wheels for the following platforms: `manylinux_2_27_aarch64`, `manylinux_2_27_x86_64`, `manylinux_2_28_aarch64`, `manylinux_2_28_x86_64`, `macosx_13_0_universal2`

please install dependency via python3 this CLI:

uv pip freeze > requirements.txt
python -m venv env
.\env\Scripts\Activate.ps1
pip install -r requirements.txt

Run

Active some workflow in main.py, then try:

# Linux or macOS
uv run main.py

# WindowsOS
python main.py