Function Compute:Use web functions to quickly create web applications

1. Develop and test the application

1. Open a new command line window locally and run the following command to install the Flask and tabulate dependency libraries required by the application into the local environment:

   pip install Flask tabulate

2. Create a folder named code and create a file named app.py in it. Paste the following sample code into the file. This code implements a simple calendar service and encapsulates it into an API. Users input year and month information (such as January 2025), and 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():
       # Obtain the request ID and print logs
       requestId = request.headers.get('x-fc-request-id', '')
       logger.info("FC Invoke Start RequestId: " + requestId)
       # Obtain the request content and check the request format
       data = json.loads(request.stream.read().decode('utf-8'))
       if not ('year' in data and 'month' in data):
           message = "Request must be in format such as {'year': '1999', 'month': '12'}"
           return message
   
       # Obtain the calendar table
       result = print_calendar(year=int(data['year']), month=int(data['month']))
       # Print logs before returning the result
       logger.info("FC Invoke End RequestId: " + requestId)
       return result
   
   
   def print_calendar(year, month):
       # Obtain the calendar matrix for the specified year and month
       cal = calendar.monthcalendar(year, month)
       # Replace dates not belonging to the specified month from 0 to an empty string
       cal = list(map(lambda sublist: list(map(lambda x: '' if x == 0 else x, sublist)), cal))
       # Create table headers
       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 the Flask application you created. When you see the output Running on http://127.0.0.1:9000, it means your Flask application has started successfully. You can now use the 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 successful, you will receive a calendar table.

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

   

At this stage, local project creation and testing are complete.

2. Generate the code package

In this step, you are going to build a code package locally for deployment to Function Compute. The code package needs to include the following contents:

• Project files required by the Flask application.

• If your application requires dependency libraries that are not included in Function Compute's built-in list, you must package those dependencies with your code. For details about built-in dependencies in web function runtimes, see Built-in dependencies.

1. Install dependencies: In the project root directory of the web application, run the following command to install the dependency libraries required by the application (in the example, tabulate).

   Note

   Python runtimes of Function Compute environment already include the Flask library, so installing tabulate alone can meet the needs of the sample application.

   pip install -t . tabulate

2. Package all files in the project root directory.

   Linux or macOS

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

   Note

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

   Windows

   Enter the project directory, select all files, right-click, and choose to package as a ZIP file. This step packages the project files and dependency libraries into a ZIP file, completing the construction of the code package.

3. Upload and deploy the code package to create the web function

1. Select the function type: Go to the Function Compute 3.0 console. In the left-side navigation pane, click Functions. In the top navigation bar, select a region (one that is close to you). Then, click Create Function. On the Create Function page, select Web Function.

2. Select the runtime: Follow the illustration to select Custom Runtime > Python > Python 3.10. This runtime has the dependency libraries required by the Flask framework built-in.

   Note

   • For web functions, we recommend that you use a Custom Runtime because this type of runtime allows you to 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 containerized deployment, you can also use a Custom Container runtime to create your web function. This type of runtime also supports concurrent request processing, but you need to manage the dependencies yourself.

   • For a detailed comparison of various runtimes, see Function runtime selection.

3. Deploy the code package: Follow the illustration to upload the ZIP package generated in the previous step and configure the startup command as python3 app.py and the listening port as 9000. If you are migrating an existing Flask application, modify the configuration as needed (for example, Flask's default port configuration is 5000).

   Then, click Create and wait for the function creation to complete.

4. Test the function

1. Obtain the function URL: On the Function Details page of the newly created function, click the Triggers tab. In the configuration information of the HTTP trigger, copy the public endpoint by clicking it.

   

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, using cURL, execute the following sample command in the command line (replace the URL with the function URL copied in the previous step).

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

   The web interface will print the calendar information for January 2025. A sample output is as follows:

   

   Note

   The sample command and output in this step are only applicable to the sample code. If you have migrated an existing application, invoke it according to the actual interface name and parameters. For more information, see Test functions using cURL.

3. (Optional) Enable browser access: The HTTP trigger's public endpoint is for testing only and will cause forced downloads if opened in a browser. We recommend that you bind your function to a custom domain name for browser and production use. For more information, see Configure custom domain names.

5. (Optional) Release resources

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