Function Compute:Quickly create a web application using web functions

1. Develop and test the web 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 interface. 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 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 run the Flask application you created. When the output is Running on http://127.0.0.1:9000, it indicates that your Flask application has started successfully. You can then 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 point, the local project creation and testing are complete.

2. Generate a code package

You will build a code package suitable for Function Compute locally. The code package needs to include the following contents:

• Project files required by the web application.

• If the dependency libraries required by the application are not in the runtime environment of the web function, the code package also needs to include these dependency libraries. For more information about the built-in dependency libraries of the web function runtime environment, 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) into the directory. After completion, the project root directory will contain project files and dependency libraries.

   Note

   The runtime environment of Python web functions already includes the Flask library, so installing tabulate 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

   Ensure 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. Create a web function and deploy the code package

1. Select the function type: Open the Function Compute 3.0 console. In the region list at the top left of the page, select the region where you want to create the function. It is recommended to choose a region close to you (such as East China 1-Hangzhou). Then, on the Function page, click Create Function. On the create function page, select Web Function.

2. Select the runtime environment: 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, it is recommended to use Custom Runtime as the function runtime environment because Custom Runtime allows you to customize the startup command and listening port and supports single-instance multi-concurrency. The Built-in Runtime does not have these features and is more suitable for handling events generated by cloud products.

   • If you prefer containerized deployment, you can also use Custom Image to create a web function. This environment also supports single-instance multi-concurrency, but you need to manage the dependencies yourself.

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

3. Deploy the code package: Follow the illustration to upload the ZIP format code package obtained 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 according to the actual startup command and port (for example, Flask's default port configuration is 5000).

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

4. Test the function

1. Obtain the function URL: On the details page of the newly created function, click the Configuration tab, then in the left-side navigation pane, select Trigger. In the configuration information of the HTTP trigger, click the public access address to copy the address.

   

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 address with the address 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. The sample output is as follows.

   

   Note

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

3. (Optional) Access the function through a browser: The public access address provided by the HTTP trigger cannot be opened with a browser (forced download) and can only be used in a test environment. It is recommended that you bind the function to a custom domain name to support browser access and production environment use. For more information, see Configure a custom domain name.

5. (Optional) Clean up resources

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