3.1 Http Trigger

Introduction

In this chapter, we will start to focus on how to use AWEL to develop a network program. First, we will create a simple HTTP trigger that receives a request and returns a response.

HttpTrigger is a special InputOperator.

Installation

We have already created a project named awel-tutorial in the previous chapter and added the dbgpt dependency.

To use the HttpTrigger operator, we need to install the fastapi and uvicorn packages.

poetry add fastapi uvicorn

The output should look like this:

➜  awel-tutorial poetry add fastapi uvicorn
Using version ^0.110.0 for fastapi
Using version ^0.27.1 for uvicorn

Updating dependencies
Resolving dependencies... (2.7s)

Package operations: 7 installs, 0 updates, 0 removals

  • Installing sniffio (1.3.1)
  • Installing anyio (4.3.0)
  • Installing click (8.1.7)
  • Installing h11 (0.14.0)
  • Installing starlette (0.36.3)
  • Installing fastapi (0.110.0)
  • Installing uvicorn (0.27.1)

Writing lock file

First HTTP Trigger

Create a new file named frist_http_trigger_hello.py in the awel_tutorial directory and add the following code:

from dbgpt.core.awel import DAG, HttpTrigger, MapOperator, setup_dev_environment

with DAG("awel_hello_world") as dag:
    trigger_task = HttpTrigger(endpoint="/awel_tutorial/hello_world")
    task = MapOperator(map_function=lambda x: f"Hello, world!")
    trigger_task >> task  
    
setup_dev_environment([dag], port=5555)

And run the following command to execute the code:

poetry run python awel_tutorial/frist_http_trigger_hello.py

And the main output should look like this:

2024-03-03 16:26:57 | INFO | dbgpt.core.awel.trigger.http_trigger | Mount http trigger success, path: /api/v1/awel/trigger/awel_tutorial/hello_world
2024-03-03 16:26:57 | INFO | dbgpt.core.awel.trigger.trigger_manager | Include router <fastapi.routing.APIRouter object at 0x10ed64e50> to prefix path /api/v1/awel/trigger
INFO:     Started server process [69774]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://127.0.0.1:5555 (Press CTRL+C to quit)

In AWEL, all HTTP endpoints are prefixed with /api/v1/awel/trigger by default.

Now, open a new terminal and run the following command to send a request to the server:

curl -X GET http://127.0.0.1:5555/api/v1/awel/trigger/awel_tutorial/hello_world

The output should look like this:

"Hello, world!"

Congratulations! You have created your first HTTP trigger.

Then you can stop the server by pressing Ctrl+C in the terminal.

How It Works

In above code, we created a HttpTrigger operator and a MapOperator operator. HttpTrigger defines the endpoint of the HTTP request, and the method of the request is "GET" by default.

The setup_dev_environment function is used to start the server and register dags, it will block the main thread if there are HttpTrigger operators in the DAG and listen on 5555 port by default.

When the server receives a request, it will call the MapOperator operator to process the request and return the result.

In HttpTrigger, you can configure the endpoint, method, request body, response body, response status code, etc.

In next section, we will introduce more about the HttpTrigger.