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Use Webhooks

You may wish to use webhooks in your client, especially when using async streams in case you want to update something in your service once the API call to LangGraph Cloud has finished running. To do so, you will need to expose an endpoint that can accept POST requests, and then pass it to your API request in the "webhook" parameter.

Currently, the SDK has not exposed this endpoint but you can access it through curl commands as follows.

The following endpoints accept webhook as a parameter:

  • Create Run -> POST /thread/{thread_id}/runs
  • Create Thread Cron -> POST /thread/{thread_id}/runs/crons
  • Stream Run -> POST /thread/{thread_id}/runs/stream
  • Wait Run -> POST /thread/{thread_id}/runs/wait
  • Create Cron -> POST /runs/crons
  • Stream Run Stateless -> POST /runs/stream
  • Wait Run Stateless -> POST /runs/wait

In this example, we will show calling a webhook after streaming a run.

Setup

First, let's setup our assistant and thread:

from langgraph_sdk import get_client

client = get_client(url=<DEPLOYMENT_URL>)
# Using the graph deployed with the name "agent"
assistant_id = "agent"
# create thread
thread = await client.threads.create()
print(thread)

import { Client } from "@langchain/langgraph-sdk";

const client = new Client({ apiUrl: <DEPLOYMENT_URL> });
// Using the graph deployed with the name "agent"
const assistantID = "agent";
// create thread
const thread = await client.threads.create();
console.log(thread);

curl --request POST \
    --url <DEPLOYMENT_URL>/assistants/search \
    --header 'Content-Type: application/json' \
    --data '{
        "limit": 10,
        "offset": 0
    }' | jq -c 'map(select(.config == null or .config == {})) | .[0]' && \
curl --request POST \
    --url <DEPLOYMENT_URL>/threads \
    --header 'Content-Type: application/json' \
    --data '{}'

Output:

{
    'thread_id': '9dde5490-2b67-47c8-aa14-4bfec88af217', 
    'created_at': '2024-08-30T23:07:38.242730+00:00', 
    'updated_at': '2024-08-30T23:07:38.242730+00:00', 
    'metadata': {}, 
    'status': 'idle', 
    'config': {}, 
    'values': None
}

Use graph with a webhook

To invoke a run with a webhook, we specify the webhook parameter with the desired endpoint when creating a run. Webhook requests are triggered by the end of a run.

For example, if we can receive requests at https://my-server.app/my-webhook-endpoint, we can pass this to stream:

# create input
input = { "messages": [{ "role": "user", "content": "Hello!" }] }

async for chunk in client.runs.stream(
    thread_id=thread["thread_id"],
    assistant_id=assistant_id,
    input=input,
    stream_mode="events",
    webhook="https://my-server.app/my-webhook-endpoint"
):
    # Do something with the stream output
    pass

// create input
const input = { messages: [{ role: "human", content: "Hello!" }] };

// stream events
const streamResponse = client.runs.stream(
  thread["thread_id"],
  assistantID,
  {
    input: input,
    webhook: "https://my-server.app/my-webhook-endpoint"
  }
);
for await (const chunk of streamResponse) {
  // Do something with the stream output
}

curl --request POST \
    --url <DEPLOYMENT_URL>/threads/<THREAD_ID>/runs/stream \
    --header 'Content-Type: application/json' \
    --data '{
        "assistant_id": <ASSISTANT_ID>,
        "input" : {"messages":[{"role": "user", "content": "Hello!"}]},
        "webhook": "https://my-server.app/my-webhook-endpoint"
    }'

The schema for the payload sent to my-webhook-endpoint is that of a run. See API Reference for more detail. Note that the run input, configuration, etc. are included in the kwargs field.

Signing webhook requests

To sign the webhook requests, we can specify a token parameter in the webhook URL, e.g., 

https://my-server.app/my-webhook-endpoint?token=...

The server should then extract the token from the request's parameters and validate it before processing the payload.

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