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Architecture

Below are diagrams illustrating how OpenCaptcha processes incoming requests and how it can be deployed via a CI/CD pipeline to Azure Container Instances.

Request Flow Diagram​

┌────────────────────┐
│   Client Request   │
│  (via HTTPS)       │
└─────────┬──────────┘
          │
          v
┌─────────────────────────┐
│  Captcha.WebApi         │
│  (Controllers, routing) │
└─────────┬───────────────┘
          │
          v
┌─────────────────────────┐
│  Captcha.Core           │
│  (Image generation)     │
└─────────┬───────────────┘
          │
          v
┌──────────────────────────┐
│  Generated Image (JPEG)  │
└──────────────────────────┘
  1. Client sends an HTTPS request to the OpenCaptcha endpoint (api.opencaptcha.io).
  2. Captcha.WebApi receives and processes the request (POST /captcha).
  3. Captcha.Core generates the CAPTCHA image based on the requested parameters (text, dimensions, difficulty).
  4. A JPEG image is returned to the client.

Deployment Diagram​

     +---------------------+
     |  GitHub Repository  |
     +----------+----------+
                |
                | (Push code to main branch)
                v
     +--------------------------------------+
     |    CI/CD Pipeline (GitHub Actions)   |
     |  - .NET build & tests                |
     |  - Docker build                      |
     +-------------+------------------------+
                   | (Push image)
                   v
     +----------------------------------+
     |  Azure Container Registry (ACR)  |
     +----------------------------------+
                   | (Pull image)
                   v
+-----------------------------------------+
|  Azure Container Apps                   |
+-----------------------------------------+
                   |
                   v
        +---------------------------------------+
        |  Publicly Accessible                  |
        |  via api.opencaptcha.io               |
        +---------------------------------------+
  1. Developers push code changes or open pull requests on GitHub.
  2. GitHub Actions (CI/CD service) automatically runs tests and builds a Docker image.
  3. The image is pushed to Azure Container Registry (ACR).
  4. Azure Container Apps pulls the Docker image from ACR.
  5. The container is deployed and made publicly available at api.opencaptcha.io.