【Introduction to the Cloud】Developing a Restful API with Python and Flask - PrismScaler

Hello! We are a writer team from Definer Inc.
In this issue, you are wondering how to develop a Restful API with Python and Flask.
Let's take a look at the actual screens and resources to explain in detail.

This article summarizes information and practices that can be helpful when you want to create a Restful API in Flask.

First, let's review the Restful APIs.
 
Restful AP is an API that satisfies the following
・Client-Server (separation of client and server)
・Stateless
・Cacheable
・Uniform Interface
・Layered System Architecture
 
For example, let's look at an actual example of an HTTP-based REST API.
・URI-based endpoints determine resources.
For example, api/user_list corresponds to a list of users.
 
・HTTP methods are used to determine resource operations.
Example: POST: add a resource
 
HTTP-based REST APIs satisfy the above conditions.

First, we will set up the Lambda setup.
Prepare the AWS SAM configuration file needed to create the Lambda function.
 
(1) Prepare configuration files
Prepare template.yaml and requirements.txt as follows.

## template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31

Resources:
  TestFunction:
    Type: AWS::Serverless::Function
    Properties:
      FunctionName: 'test'
      CodeUri: hello_world/
      Handler: app.lambda_handler
      Runtime: python3.9
      Events:
        ApiRoot:
          Type: Api
          Properties:
            Path: '/'
            Method: ANY
        ApiProxy:
          Type: Api
          Properties:
            Path: '/{proxy+}'
            Method: ANY
                

In requirements.txt, add the following three lines.

requests
Flask
aws-wsgi                  

Next, we will implement Lambda.
 
(1) Preparation of Lambda sample code
Copy and paste the following code into app.py.

import awsgi
from flask import Flask, request, render_template
app = Flask(__name__)

@app.route('/hello', methods=['GET'])
def hello_get():
    return {'msg': 'hello world'}

def lambda_handler(event, context):
    return awsgi.response(app, event, context)                

(2) Deploying Lambda
Deploy Lambda using the "sam build" and "sam deploy" commands.
 
(3) Testing the API
Note the API endpoint URL and make an API call using the Curl command.
The response comes back as expected!
 

## ビルド
sam build

## deploy
sam deploy --guided


## API Testing
curl -X GET https:/${API Endpoint URL}/${Stage name}/hello

## Test Results
{"msg":"hello world"}                  

Troubleshooting API Gateway HTTP 504 Timeout Errors ...
Troubleshooting HTTP 403 errors from API Gateway
Developing a RESTful API with Python and Flask
Developing a RESTful API with Flask - Japanese garbled in jsonify ...
Reference articles on developing APIs with Python's Flask | iret.media
Python Flask API Development - Qiita
[Python] Using decorators ｜ Engineer as much as you play

・PrismScaler is a web service that enables the construction of multi-cloud infrastructures such as AWS, Azure, and GCP in just three steps, without requiring development and operation.
・PrismScaler is a web service that enables multi-cloud infrastructure construction such as AWS, Azure, GCP, etc. in just 3 steps without development and operation.
・The solution is designed for a wide range of usage scenarios such as cloud infrastructure construction/cloud migration, cloud maintenance and operation, and cost optimization, and can easily realize more than several hundred high-quality general-purpose cloud infrastructures by appropriately combining IaaS and PaaS.
 

This article provides useful introductory information free of charge. For consultation and inquiries, please contact "Definer Inc".

・Definer Inc. provides one-stop solutions from upstream to downstream of IT.
・We are committed to providing integrated support for advanced IT technologies such as AI and cloud IT infrastructure, from consulting to requirement definition/design development/implementation, and maintenance and operation.
・We are committed to providing integrated support for advanced IT technologies such as AI and cloud IT infrastructure, from consulting to requirement definition, design development, implementation, maintenance, and operation.
・PrismScaler is a high-quality, rapid, "auto-configuration," "auto-monitoring," "problem detection," and "configuration visualization" for multi-cloud/IT infrastructure such as AWS, Azure, and GCP.