There are many situations in which it is useful to run an assistant on a schedule. For example, say that you’re building an assistant that runs daily and sends an email summary of the day’s news. You could use a cron job to run the assistant every day at 8:00 PM. LangGraph Platform supports cron jobs, which run on a user-defined schedule. The user specifies a schedule, an assistant, and some input. After that, on the specified schedule, the server will:
  • Create a new thread with the specified assistant
  • Send the specified input to that thread
Note that this sends the same input to the thread every time. The LangGraph Platform API provides several endpoints for creating and managing cron jobs. See the API reference for more details. 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 Platform 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.

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Setup

First, let’s set up 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)
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
}

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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?"}]},
)
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"])

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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?"}]},
)
Again, remember to delete your job once you are done with it! 
await client.crons.delete(cron_job_stateless["cron_id"])