Lab.GCP.API-Gateway

A basic API with Google Cloud API Gateway, OpenAPI 2.0, Google Cloud Functions, Flask, Google Cloud Firestore and Terraform.

NOTE:

GCP Deployment Manager is not developed very actively by Google. Important resources are missing, like for example API Gateway or Firestore. Other resources are not up-to date, e.g. Cloud Functions, which does not support yet V2.

On the other side Google is pushing Terraform. Therefore Terraform is used here instead of Deployment manager.

• Google Cloud API Gateway
• OpenAPI 2.0
• Google Cloud Functions
• Cloud Functions Framework
• Google Cloud Firestore
• Terraform

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
    GCP API Gateway
    ―――――――――
    Concerts API
`") -->|invoke| Handler

Handler("`
    fa:fa-code
    GCP Function
    ――――――――――
    concerts_api_handler
`") -->|query/add| Database
Handler -->|response| API

Database[("`
    fa:fa-database
    GCP Firestore
    ――――――――――
    Concerts collection
`")] -->|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
    "]

Loading

Handler

classDiagram

class Flask {
   route()
   test_request_context()
   full_dispatch_request()
}

router --|> Flask
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 {
   collection

   find_concert_by_artist()
   create_concert()
   concert_to_document()
   document_to_concert()
}

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Database

erDiagram

concerts-collection {}
concerts-collection ||--|{ concert-document : contains
concert-document {
    string artist
    string concert
    number ticket_sales
    timestamp create_date
}

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Development

Dependencies

1. Install latest gcloud CLI https://cloud.google.com/cli and setup with gcloud init
2. Install Terraform or OpenTofu:
   • Terraform https://developer.hashicorp.com/terraform/downloads (Install binary, if APT repository is not working)
   • OpenTofu https://github.com/opentofu/opentofu (Currently [01/10/2023] not yet stable enough)
3. Install Python 3.9

Recommended Visual Studio Code plugins

• https://marketplace.visualstudio.com/items?itemName=redhat.vscode-yaml
• https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one
• https://marketplace.visualstudio.com/items?itemName=4ops.terraform

Deployment

# Login to Google Cloud from terminal
gcloud auth application-default login

# Create a new gcloud project
gcloud projects create "concerts-2023"
gcloud config set project "concerts-2023"

# Enable services
gcloud services enable artifactregistry.googleapis.com cloudapis.googleapis.com cloudbuild.googleapis.com cloudfunctions.googleapis.com logging.googleapis.com monitoring.googleapis.com pubsub.googleapis.com run.googleapis.com storage-api.googleapis.com storage-component.googleapis.com storage.googleapis.com deploymentmanager.googleapis.com apigateway.googleapis.com firestore.googleapis.com servicecontrol.googleapis.com

Terraform deployment

cd src

# Initialize Terraform project and download providers
terraform init

# Deploy resources with Terraform
terraform apply

NOTE:

In this simple Terraform setup, the state file is created locally. For a production-ready setup, the state file should be synchronized to the cloud, e.g. the HashiCorp cloud or a Google Storage bucket.

Cleanup

# Cleanup resources deployed with Terraform
terraform destroy

# Firestore is in beta phase and can only be deleted by CLI
gcloud alpha firestore databases delete --database="(default)"

Test cases

• Create concert

    curl -X PUT --location 'https://concerts-api-gateway-dev-5pksjh0d.nw.gateway.dev/concerts'
        -H 'Content-Type: application/json'
        -d '{"artist":"Madonna","concert":"In time", "ticket_sales": 67280}'
  

• Empty PUT

    curl -X PUT --location 'https://concerts-api-gateway-dev-5pksjh0d.nw.gateway.dev/concerts'
        -H 'Content-Type: application/json'
  

• Missing PUT parameters

    curl -X PUT --location 'https://concerts-api-gateway-dev-5pksjh0d.nw.gateway.dev/concerts'
        -H 'Content-Type: application/json'
        -d '{"artist":"Madonna","concert":"This is Madonna 2023", "wrong_param": 500}'
  

• Invalid PUT parameters

    curl -X PUT --location 'https://concerts-api-gateway-dev-5pksjh0d.nw.gateway.dev/concerts'
        -H 'Content-Type: application/json'
        -d '{"artist":"Madonna","concert":"This is Madonna 2023", "ticket_sales": -5}'
  

• List concerts

    curl --location 'https://concerts-api-gateway-dev-5pksjh0d.nw.gateway.dev/concerts?artist=Madonna'
  

• Invalid list parameters

    curl --location 'https://concerts-api-gateway-dev-5pksjh0d.nw.gateway.dev/concerts?song_writer=Madonna'
  

Resources

• Create a 2nd gen Cloud Function by using the Google Cloud CLI
• How to use Google API Gateway with Cloud Run
• API Gateway > Documentation > Passing data to and from the backend service <<<<<<< HEAD
• Least privilege for Cloud Functions using Cloud IAM =======
• Least privilege for Cloud Functions using Cloud IAM

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