langgraph-func

Expose LangGraph workflows as Azure Function HTTP endpoints.

Installation

poetry add langgraph_func

Requires Python ≥3.10, LangGraph, Azure Functions SDK.

Define a Workflow

from pydantic import BaseModel
from langgraph.graph import StateGraph, START
from typing import Optional

class Input(BaseModel):
    input_text: str

class Output(BaseModel):
    update: Optional[str] = None

class MergedState(Input, Output):
    pass

def test(state: MergedState) -> dict:
    return {"update": "ok"}

compiled_graph = StateGraph(input=Input, output=Output) \
    .add_node("test", test) \
    .add_edge(START, "test") \
    .set_finish_point("test") \
    .compile(name="test_graph")

Configuration (function-app.yml)

swagger:
  title: Test Function App
  version: 1.0.0-beta
  auth: FUNCTION
  ui_route: docs

blueprints:
  blueprint_a:
    path: blueprint_a
    description: |
      Groups related graphs.
    graphs:
      graphA:
        path: graphA
        source: graphs.graph
        auth: FUNCTION
        description: |
          GraphA ingests raw input.
      parentGraph:
        path: parentGraph
        source: graphs.parent_graph
        auth: FUNCTION
        description: |
          Calls a subgraph from a parent.

Run in Azure Functions

from langgraph_func.func_app_builder.create_app import create_app_from_yaml
app = create_app_from_yaml("function-app.yml")

Deploy with func azure functionapp publish <APP_NAME>.

Calling Subgraphs

class Input(BaseModel):
    input_text: str
class Output(BaseModel):
    child_update: Optional[str] = None
    
# create one invoker instance
subgraph = AzureFunctionInvoker(
    function_path="blueprint_a/graphA",
    base_url=settings.function_base_url,
    input_field_map={"input_text": "text"},
    output_field_map={"updates": "child_update"},
    auth_key=FunctionKeySpec.INTERNAL,
)
compiled_graph = (
    StateGraph(input=Input, output=Output)
      .add_node("call_graphA", subgraph)
      .add_edge(START, "call_graphA")
      .set_finish_point("call_graphA")
      .compile()
)

Documentation

See GitHub Pages for full API reference and examples.