captcha-microservice

REST based captcha generating microservice

Consists of the following types:

• Image To Text

  

  (Ans: dfl22V)

• Math Challenge

  

  (Ans: 64)

Workflow

• Request captcha using one of the methods
• Response body is the raw body of the captcha (image/sound) and Captcha Id will be provided in X-Captcha-Session-Id header
• Answer can be verified using the /verify endpoint providing a JWT token
• JWT token can be used to confirm authenticity on server side or client side with /verify endpoint

Methods

Random Captcha

/captcha/captcha

Get a random captcha from all the methods supported

Header: X-Captcha-Session-Id - contains the captcha id

Body is raw content of the captcha (image/sound)

Image Captcha

/captcha/imageCaptcha

Get image captcha

Header: X-Captcha-Session-Id - contains the captcha id

Body is raw image in png format

Math Captcha

/captcha/mathCaptcha

Get math challenge which gives a math equation

Header: X-Captcha-Session-Id - contains the captcha id

Body is raw image in png format

Verify

/verify?sessionId=<captchaId>&solution=<solution>

Verify captcha answer. A JWT token is returned if the answer is correct (200 status code), else 401 status code is returned

Validate

/validate?sessionId=<captchaId>&token=<token>

Can be used server side to validate the verification

Usage

As a service

Environment Variables

PORT=                   Application port
JWT_SECRET=             JWT signing secret
HOST=                   Hostname to use in JWT token
PROMETHEUS_SECRET=      Prometheus secret (Use with header
                        Authorization: Bearer <PROMETHEUS_SECRET>)
RATE_LIMIT_DURATION=    Rate limit duration in seconds
RATE_LIMIT_POINTS=      Rate limit points for given duration
REDIS_HOST=             Redis host
REDIS_PORT=             Redis port
REDIS_PASSWORD=         Redis password
REDIS_DB=               Redis database
REDIS_USERNAME=         Redis username
CAPTCHA_TIMEOUT=        Captcha timeout in seconds

Docker

docker run -d --name captcha-microservice --env-file app.env -p 5555:5555 crossphoton/captcha-microservice:v1.0.0

Kubernetes

There are 4 components to deploy:

• Redis - For session id to solution mapping
• Secrets - For configuration
• Captcha Microservice - The main service
• Ingress - For exposing the service

For ingress make sure that ingress is configured. (Use nginx ingress for digital ocean)

Locally

1. Clone repository
2. Run npm install
3. Run dotenv -e app.env -- npm start

Additional Parts

• Prometheus : /metrics endpoint with proper authorization can be used to collect metrics
• Logging : is done using winston.
• Shutdown management : done using lightship

License

MIT License