Lab.AWS.API-Gateway

A basic serverless API with AWS API Gateway, OpenAPI 3.0, AWS Lambda, Lambda Powertools for Python, AWS DynamoDB and AWS SAM.

• AWS API Gateway
• OpenAPI 3.0
• AWS Lambda
• Python Powertools for AWS Lambda
• AWS DynamoDB
• AWS Serverless Application Model (SAM)

API Handler clean code practices:

• MVC pattern - https://python.plainenglish.io/model-view-controller-mvc-pattern-in-python-a-beginners-guide-b0d9855068eb
• Repository pattern - https://medium.com/@pererikbergman/repository-design-pattern-e28c0f3e4a30
• Validators
• Router

Architecture

flowchart LR

API("`
    fa:fa-th-large
    AWS API Gateway
    ―――――――――
    Concerts API
`") -->|invoke| Handler

Handler("`
    fa:fa-code
    AWS Lambda Function
    ――――――――――
    concerts_api_handler
`") -->|query/put| Database
Handler -->|response| API

Database[("`
    fa:fa-database
    AWS DynamoDB
    ――――――――――
    concerts table
`")] -->|Concerts| Handler

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API

flowchart LR
    API("
        API
        ――
        /
    ")

    API --> concerts

    concerts["
        endpoint
        ―――――
        concerts/
    "]

    concerts --> get["
        GET
        ―――――――――
        query parameters:
        - artist=string
        returns:
        - Concert[]
    "]
    concerts --> put["
        PUT
        ―――――――――
        request body:
        - artist: string
        - concert: string
        - ticket_sales: number
        returns:
        - Concert
    "]

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Handler

classDiagram

class APIGatewayHttpResolver {
   get()
   put()
   resolve()
}

router --|> APIGatewayHttpResolver
router: get_concerts()
router: put_concert()
router --> ConcertController: resolve route

class ConcertController {
   repository

   get_concerts_action()
   put_concert_action()
}
ConcertController --> ConcertRepository: Find / Create concert(s)
ConcertController --> concert_validator: Validate event

concert_validator: validate_get_concerts_event()
concert_validator: validate_put_concert_event()

class Concert {
   string artist
   string concert
   int ticket_sales
   datetime create_date

   validate()
   from_dto()
   dto()
}

class ConcertRepository {
   table_name
   table

   find_concert_by_artist()
   create_concert()
   concert_to_record()
   record_to_concert()
}

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Database

erDiagram

concerts-table {}
concerts-table ||--|{ concert-record : contains
concert-record {
    string artist
    string concert
    decimal ticket_sales
    decimal create_date
}

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Development

Dependencies

1. Install latest AWS CLI https://docs.aws.amazon.com/cli/latest/userguide/getting-started-version.html
2. Install AWS SAM CLI https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/install-sam-cli.html
3. Install Python 3.9

Recommended Visual Studio Code plugins

• https://marketplace.visualstudio.com/items?itemName=tamasfe.even-better-toml
• https://marketplace.visualstudio.com/items?itemName=redhat.vscode-yaml
• https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one

Deployment

For instructions regarding SAM, see https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/using-sam-cli.html.

SAM deployment

cd src

# Build & deploy
sam build
sam deploy --config-env dev

# Develop interactively
sam sync --stack-name concerts-api-dev --watch

# Stack outputs
sam list stack-outputs --stack-name concerts-api-dev

Cleanup

# Delete stack
sam delete --config-env dev
# or
aws cloudformation delete-stack --stack-name concerts-api-dev
# To remove all SAM resources completely, also the stack aws-sam-cli-managed-default needs to be deleted
aws cloudformation delete-stack --stack-name aws-sam-cli-managed-default

Try it out

Create a concert

# Replace API_ID by the actual ID
curl -X PUT --location 'https://{API_ID}.execute-api.eu-central-1.amazonaws.com/dev/concerts' \
    -H 'Content-Type: application/json' \
    -d '{"artist":"Madonna","concert":"This is Madonna 2023","ticket_sales": 5000000 }'

List concerts

Open https://{API_ID}.execute-api.eu-central-1.amazonaws.com/dev/concerts?artist=Madonna in your browser (replace API_ID by the actual ID)

Additional Resources

• Python doc comments with Sphinx: https://www.sphinx-doc.org/en/master/usage/restructuredtext/domains.html#python-signatures