Running an executable on Heroku upon Flask API endpoint access

After installation login into the Heroku Cli by running this command in the terminal.

heroku login

Let us start by cloning the application. Open the terminal and paste in this command to clone the application. A gentle reminder that this step will only work if you have Git installed on your computer.

git clone https://github.com/jokamjohn/bucket_api_heroku.git

Open the folder bucket_api_heroku with your favorite text editor or IDE. Create a virtual environment and install the dependencies by running.

pip install -r requirements.txt

Before we can add a Procfile, we need to first install a web server called Gunicorn. Run the following command within the application folder.

pip install gunicorn

Update the requirements file by running

pip freeze > requirements.txt

In your project directory, let's start off by creating a virtualenv:

$ python -m venv venv/

And let's activate it with the source command:

$ source venv/bin/activate

Then, let's use pip to install the libraries we're going to use - flask to build the app and gunicorn as our server:

$ pip install flask
$ pip install gunicorn

Our application is going to be a simple API that receives a name and returns a welcome message:

# app.py
from flask import Flask, request, jsonify
app = Flask(__name__)

@app.route('/getmsg/', methods=['GET'])
def respond():
    # Retrieve the name from url parameter
    name = request.args.get("name", None)

    # For debugging
    print(f"got name {name}")

    response = {}

    # Check if user sent a name at all
    if not name:
        response["ERROR"] = "no name found, please send a name."
    # Check if the user entered a number not a name
    elif str(name).isdigit():
        response["ERROR"] = "name can't be numeric."
    # Now the user entered a valid name
    else:
        response["MESSAGE"] = f"Welcome {name} to our awesome platform!!"

    # Return the response in json format
    return jsonify(response)

@app.route('/post/', methods=['POST'])
def post_something():
    param = request.form.get('name')
    print(param)
    # You can add the test cases you made in the previous function, but in our case here you are just testing the POST functionality
    if param:
        return jsonify({
            "Message": f"Welcome {name} to our awesome platform!!",
            # Add this option to distinct the POST request
            "METHOD" : "POST"
        })
    else:
        return jsonify({
            "ERROR": "no name found, please send a name."
        })

# A welcome message to test our server
@app.route('/')
def index():
    return "<h1>Welcome to our server !!</h1>"

if __name__ == '__main__':
    # Threaded option to enable multiple instances for multiple user access support
    app.run(threaded=True, port=5000)

We can also send a name as a parameter, such as http://localhost:5000/getmsg/?name=Mark:

{"MESSAGE":"Welcome Mark to our awesome platform!!"}