In the project, I decided to create a simple API using Python, so I will prepare the environment to create the API quickly.

Premise

Editor ... VS Code OS…Windows10 Python 3.8 installed AWS CLI installed

Installing AWS CLI Version 2 on Windows-AWS Command Line Interface

Required environment

AWS SAM CLI
AWS Toolkit for Visual Studio Code

Benefits of AWS SAM

According to the Official Document

--Single deployment configuration --AWS CloudFormation extensions --Built-in best practices --Local debugging and testing --Tight integration with development tools

Is a merit. Personally, being able to debug lambda locally was a big advantage. Since the actual situation is CloudFormation, it is also highly customizable.

Introducing the AWS SAM CLI

Follow the Official Documents. In summary

Install docker

Install from the installer (.msi file) distributed by AWS or install with pip install aws-sam-cli

OK if the version is output with sam --version

docker is installed to create a lambda execution environment on the local machine.

Introducing AWS Toolkit for Visual Studio Code

This is a VS Code extension for working with AWS SAMs from VS Code with a GUI. AWS Toolkit - Visual Studio Marketplace

Create a new project

Follow the Official Documents.

Open the command palette (Ctrl + Shift + P) and select Create new SAM Application
Select the runtime you want to use. This time Python 3.8
Select a template. This time I will use it alone, so Hwllo World
Specify the directory where you want to create the project. Explorer will open, so select any folder.
Specify the project name. Press Enter to create the project.

Run local debug

Open hello_world / app.py and select Debug Locally to create a virtual environment in docker and execute the function.
OK if the result is output to the debug console

set event

.aws/templates.jsonで設定できる

Deploy

We will deploy based on template.yaml.

Select Deploy SAM Application from the command palette
Select a template. This time templete.yaml
Select any deployment destination region. This time Tokyo
Specify the S3 bucket name. You must specify an existing bucket name here.
Specify the Stack name. Stack is the name of the service group created by CloudFormation. It has the same name as the project name.
If the deployment is successful, the debug console will be displayed.

Confirm that it has been deployed

You can see that the lambda is created as shown below. You can see that the API is also created in API Gateway.

Customize

The API created by default is GET: / hello, so you need to edit templete.yaml to change this.

Below is the default templete.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  trial-sam

  Sample SAM Template for trial-sam

# More info about Globals: https://github.com/awslabs/serverless-application-model/blob/master/docs/globals.rst
Globals:
  Function:
    Timeout: 3

Resources:
  HelloWorldFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    Properties:
      CodeUri: hello_world/
      Handler: app.lambda_handler
      Runtime: python3.8
      Events:
        HelloWorld:
          Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
          Properties:
            Path: /hello
            Method: get

Outputs:
  # ServerlessRestApi is an implicit API created out of Events key under Serverless::Function
  # Find out more about other implicit resources you can reference within SAM
  # https://github.com/awslabs/serverless-application-model/blob/master/docs/internals/generated_resources.rst#api
  HelloWorldApi:
    Description: "API Gateway endpoint URL for Prod stage for Hello World function"
    Value: !Sub "https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/hello/"
  HelloWorldFunction:
    Description: "Hello World Lambda Function ARN"
    Value: !GetAtt HelloWorldFunction.Arn
  HelloWorldFunctionIamRole:
    Description: "Implicit IAM Role created for Hello World function"
    Value: !GetAtt HelloWorldFunctionRole.Arn

You can change the path and HTTP method by rewriting this as follows

Before

Resources:
  HelloWorldFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    Properties:
      CodeUri: hello_world/
      Handler: app.lambda_handler
      Runtime: python3.8
      Events:
        HelloWorld:
          Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
          Properties:
            Path: /hello
            Method: get

After

Resources:
  HelloWorldFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    Properties:
      CodeUri: hello_world/
      Handler: app.lambda_handler
      Runtime: python3.8
      Events:
        HelloWorld:
          Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
          Properties:
            Path: /anypath # hello → anypath
            Method: post # get → post

POST: I was able to change to ʻanypath`.

All you have to do is write the logic

All you have to do is assemble the logic according to your requirements.

If you deploy again, your changes will take effect.

Create API with Python, lambda, API Gateway quickly using AWS SAM