Function Compute:Quickly create a web application using web functions

Step 1: Develop and test the web application

1. Open a new command line window on your local machine. Run the following command to install the Flask and tabulate dependency libraries required by the application in your local environment.

   pip install Flask tabulate

2. Create a folder named code and a file named app.py in the folder. Paste the following sample code into the file. This code implements a simple calendar service and encapsulates it as an API. When a user provides a year and month, such as January 2025, the API returns the corresponding calendar table.

   import calendar
   from flask import Flask, request
   from tabulate import tabulate
   import logging
   import json
   
   logger = logging.getLogger()
   app = Flask(__name__)
   
   
   @app.route("/", methods=["POST"])
   def get_month_calendar():
       # Get the request ID and print the log.
       requestId = request.headers.get('x-fc-request-id', '')
       logger.info("FC Invoke Start RequestId: " + requestId)
       # Get the request body and check its format.
       data = json.loads(request.stream.read().decode('utf-8'))
       if not ('year' in data and 'month' in data):
           message = "Request must be in a format such as {'year': '1999', 'month': '12'}"
           return message
   
       # Get the calendar table.
       result = print_calendar(year=int(data['year']), month=int(data['month']))
       # Print a log before returning the result to indicate that the function execution is complete.
       logger.info("FC Invoke End RequestId: " + requestId)
       return result
   
   
   def print_calendar(year, month):
       # Get the calendar matrix for the specified year and month.
       cal = calendar.monthcalendar(year, month)
       # Replace 0 with an empty string for days that are not in the specified month.
       cal = list(map(lambda sublist: list(map(lambda x: '' if x == 0 else x, sublist)), cal))
       # Create the table header.
       headers = ["Mo", "Tu", "We", "Th", "Fr", "Sa", "Su"]
   
       # Use tabulate to print the calendar table.
       return tabulate(cal, headers=headers, tablefmt="grid", stralign='center', numalign='center')
   
   
   if __name__ == "__main__":
       app.run(host='0.0.0.0', port=9000)
   

3. Run the python3 app.py command to start your Flask application. When the output shows Running on http://127.0.0.1:9000, your Flask application has started successfully. You can then use a cURL command to test the application.

   python3 app.py 
    * Serving Flask app 'app'
    * Debug mode: off
   WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
    * Running on http://127.0.0.1:9000
    * Running on http://47.100.XX.XX:9000
   Press CTRL+C to quit

4. Open a new terminal window and use cURL to send a sample request. If the command is executed successfully, a calendar table is returned.

   curl -X POST http://127.0.0.1:9000 -d '{"year": "2000", "month": "1"}'

   

This completes the local project creation and testing.

Step 2: Generate a code package

Build a local code package for Function Compute. The code package must contain the following items:

• The project files required by the web application.

• If the dependency libraries required by the application are not in the web function's runtime environment, the code package must also include these libraries. For more information about the built-in dependency libraries in the web function runtime environment, see Built-in dependencies.

1. Install dependencies: In the root directory of the web application project, run the following command to install the required dependency libraries (tabulate in this example) in the directory. After the command is executed, the root directory of the project contains the project files and dependency libraries.

   Note

   The Python runtime for web functions already includes the Flask library. Therefore, you only need to install tabulate to meet the requirements of the sample application.

   pip install -t . tabulate

2. Package all files in the root directory of the project.

   Linux or macOS

   In the root directory of the project, run zip code.zip -r ./*. This command packages the project files and dependency libraries into a ZIP file. This completes the code package creation.

   Note

   Make sure that you have read and write permissions on the directory.

   Windows

   Go to the project directory, select all files, right-click the selected files, and then package them into a ZIP file. This command packages the project files and dependency libraries into a ZIP file. This completes the code package creation.

Step 3: Create a web function and deploy the code package

1. Select the web function type: Log on to the Function Compute console. In the navigation pane on the left, choose Functions > Functions. In the top navigation bar, select the region where you want to create the function. Click Create Function, select Web Function, and then follow the prompts to create the function.

2. Select the runtime: Select Custom Runtime > Python > Python 3.10. This runtime has built-in dependency libraries for the Flask framework.

   Note

   • For web functions, we recommend that you use a Custom Runtime. A Custom Runtime lets you customize the startup command and listening port, and supports concurrent request handling. A Built-in Runtime does not have these features and is more suitable for handling events generated by other Alibaba Cloud services.

   • If you prefer a containerized deployment, you can also use a Custom Image to create a web function. This environment also supports concurrent requests on a single instance, but you must manage the dependencies yourself.

   • For a detailed comparison of the different runtime environments, see Runtime environment comparison.

3. Deploy the code package: Upload the ZIP code package that you obtained in Step 2. Set the startup command to python3 app.py and the listening port to 9000. If you are migrating an existing Flask application, modify the configuration to match your application's startup command and port. For example, the default port for Flask is 5000.

   After you complete the configuration, click Create and wait for the function to be created.

Step 4: Test the function

1. Obtain the function URL: On the function details page, click the Triggers tab. In the configuration column of the target HTTP trigger, obtain the public endpoint.

   If you are in a test environment that does not require authentication, you can set the Authentication Method to No Authentication when you create the HTTP trigger or by modifying it afterward.

   

2. Test the function: You can use cURL, Postman, or any HTTP client to invoke the function and verify the functionality of the Flask application. For example, to use cURL, run the following sample command in the command line. Replace the URL with the one you obtained in the previous step.

   curl https://******.cn-hangzhou.fcapp.run -d '{"year": "2025", "month": "1"}' 

   The command returns the calendar information for January 2025. The following output is a sample.

   

   Note

   • If you use the default HTTP trigger configuration, running the preceding sample command returns a MissingRequiredHeader error. In this case, if you are in a test environment, you can change the Authentication Method of the trigger to No Authentication.

   • The sample command and output in this step apply only to the sample code. If you migrated an existing application, invoke your service based on the actual API operation name and parameters. For more information, see Test a function using cURL.

3. (Optional) Access the function from a browser: The public endpoint provided by the HTTP trigger cannot be accessed from a browser because it forces a file download. This endpoint is intended for testing purposes only. We recommend that you bind a custom domain name to the function to enable browser access and for use in a production environment. For more information, see Configure a custom domain name.

(Optional) Step 5: Clean up resources

For steps to add dependencies for each language, see the following documents: