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Cron Jobs

Sometimes you don't want to run your graph based on user interaction, but rather you would like to schedule your graph to run on a schedule - for example if you wish for your graph to compose and send out a weekly email of to-dos for your team. LangGraph Cloud allows you to do this without having to write your own script by using the Crons client. To schedule a graph job, you need to pass a cron expression to inform the client when you want to run the graph. Cron jobs are run in the background and do not interfere with normal invocations of the graph.

Setup

First, let's setup our SDK client, 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].graph_id' && \
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
}

Cron job on a thread

To create a cron job associated with a specific thread, you can write:

# This schedules a job to run at 15:27 (3:27PM) every day
cron_job = await client.crons.create_for_thread(
    thread["thread_id"],
    assistant_id,
    schedule="27 15 * * *",
    input={"messages": [{"role": "user", "content": "What time is it?"}]},
)

// This schedules a job to run at 15:27 (3:27PM) every day
const cronJob = await client.crons.create_for_thread(
  thread["thread_id"],
  assistantId,
  {
    schedule: "27 15 * * *",
    input: { messages: [{ role: "user", content: "What time is it?" }] }
  }
);

curl --request POST \
    --url <DEPLOYMENT_URL>/threads/<THREAD_ID>/runs/crons \
    --header 'Content-Type: application/json' \
    --data '{
        "assistant_id": <ASSISTANT_ID>,
    }'

Note that it is very important to delete Cron jobs that are no longer useful. Otherwise you could rack up unwanted API charges to the LLM! You can delete a Cron job using the following code:

await client.crons.delete(cron_job["cron_id"])

await client.crons.delete(cronJob["cron_id"]);

curl --request DELETE \
    --url <DEPLOYMENT_URL>/runs/crons/<CRON_ID>

Cron job stateless

You can also create stateless cron jobs by using the following code:

# This schedules a job to run at 15:27 (3:27PM) every day
cron_job_stateless = await client.crons.create(
    assistant_id,
    schedule="27 15 * * *",
    input={"messages": [{"role": "user", "content": "What time is it?"}]},
)

// This schedules a job to run at 15:27 (3:27PM) every day
const cronJobStateless = await client.crons.create(
  assistantId,
  {
    schedule: "27 15 * * *",
    input: { messages: [{ role: "user", content: "What time is it?" }] }
  }
);

curl --request POST \
    --url <DEPLOYMENT_URL>/runs/crons \
    --header 'Content-Type: application/json' \
    --data '{
        "assistant_id": <ASSISTANT_ID>,
    }'

Again, remember to delete your job once you are done with it!

await client.crons.delete(cron_job_stateless["cron_id"])

await client.crons.delete(cronJobStateless["cron_id"]);

curl --request DELETE \
    --url <DEPLOYMENT_URL>/runs/crons/<CRON_ID>

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