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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 Instances (Windows)    |
+-----------------------------------------+
                   |
                   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 Instances (Windows-based) pulls the Docker image from ACR.
  5. The container is deployed and made publicly available at api.opencaptcha.io.