Overview

This document describes how to quickly deploy a Flask business to the cloud through an SCF web function.

Note：

This document mainly describes how to deploy in the console. You can also complete the deployment on the command line. For more information, please see Deploying Framework on Command Line.

Prerequisites

Before using SCF, you need to sign up for a Tencent Cloud account and complete identity verification first.

Directions

Template deployment - quick deployment of Flask project

1. Log in to the SCF console and click Function Service on the left sidebar.
2. Select the region where to create a function at the top of the page and click Create to enter the function creation process.
3. Select Template for Creation Method, enter WebFunc in the search box to filter all web function templates, select Flask Framework Template, and click Next as shown below:
   
4. On the Configuration page, you can view and modify the specific configuration information of the template project.
5. Click Complete. After creating the web function, you can view its basic information on the Function Management page.
6. You can access the deployed Flask project at the access path URL generated by API Gateway. Click Trigger Management on the left to view the access path as shown below:
   
7. Click the access path URL to access the Flask project.

Custom deployment - quick migration of local project to cloud

Local development

1. Run the following command to confirm that Flask has been installed in your local environment.

   pip install Flask
   

2. Create the Hello World sample project locally.
   In the project directory, create the app.py file to implement the Hello World application. Below is the sample code:

   from flask import Flask
   app = Flask(__name__)
   
   @app.route('/')
   def hello_world():
      return 'Hello World'
   
   if __name__ == '__main__':
      app.run()

3. Run the python3 app.py command locally to start the app.py file. Below is the sample code:

   $ python3 app.py
    * Serving Flask app "app" (lazy loading)
    * Environment: production
      WARNING: Do not use the development server in a production environment.
      Use a production WSGI server instead.
    * Debug mode: off
    * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
   127.0.0.1 - - [22/Jun/2021 09:41:04] "GET / HTTP/1.1" 200 -

4. Visit http://127.0.0.1:5000 in a browser, and you can access the sample Flask project locally as shown below:
   

Deployment in cloud

Next, perform the following steps to make simple modifications to the locally created project, so that it can be quickly deployed through a web function. The steps of project transformation for Flask are as follows:

1. Install dependencies

   1. As the Flask dependency library is not provided in the standard cloud environment of SCF, you must install the dependencies and upload them together with the project code. Please create the requirements.txt file first with the following content:

      #requirements.txt
      Flask==1.0.2
      werkzeug==0.16.0
      

   2. Run the following command to install:

      pip install -r requirements.txt
      

2. Modify the listening address and port
   The listening port in the web function must be 9000, so you need to change the listening address and port to 0.0.0.0:9000 as shown below:
   

   Note：

   You can also configure the listening port through the environment variable in scf_bootstrap.

3. Add the scf_bootstrap bootstrap file

   1. Create the scf_bootstrap bootstrap file in the project root directory and add the following content to it (which is used to configure environment variables, specify service bootstrap commands, and make sure that your service can be started normally through this file):

      #!/bin/bash
      /var/lang/python3/bin/python3 app.py
      

   2. After the creation is completed, you need to run the following command to modify the executable permission of the file. By default, the permission 777 or 755 is required for it to start normally. Below is the sample code:

      chmod 777 scf_bootstrap
      

Note：

• In the SCF environment, only files in the /tmp directory are readable/writable. We recommend you select /tmp when outputting files. If you select other directories, write will fail due to the lack of permissions.
• If you want to output environment variables in the log, you need to add the -u parameter before the bootstrap command, such as python -u app.py.

4. After the local configuration is completed, run the following command to start the service (with execution in the scf_bootstrap directory as an example) and make sure that your service can be normally started locally.
   ./scf_bootstrap

5. Log in to the SCF console and click Function Service on the left sidebar.
6. Select the region where to create a function at the top of the page and click Create to enter the function creation process.
7. Select Custom Creation for Creation Method and configure the options as prompted as shown below:
   
   • Function Type: select Web function.
   • Function Name: enter the name of your function.
   • Region: enter your function deployment region, such as Chengdu.
   • Deployment Method: select Code deployment and upload your local project.
   • Runtime Environment: select Python 3.6.
8. Click Complete.

Development management

After the deployment is completed, you can quickly access and test your web service in the SCF console and try out various features of SCF, such as layer binding and log management. In this way, you can enjoy the advantages of low cost and flexible scaling brought by the serverless architecture.