How to verify that an HTTP request came from an internal cron?

I've recently setup a cron process that will make an internal request inside my K8 instance call my service internally. I'm now faced with the task of securing that endpoint. The simplest solution might be to pass a secret via the Authorization header but that doesn't seem safe or the proper way.

What are some correct ways to detect and allow a request to a specific endpoint on my RESTful API?

Since any traffics from outside will go through an ingress in order to reach your HTTP service, you can add a routing to an error page component if the traffics reach the API paths meant for your internal cron usage, which calls the API via the service and not going through the ingress.

For example:

spec:
  rules:
  - host: api.domain.com
    http:
      paths:
      - backend:
          service:
            name: api-service
            port:
              number: 80
        path: /(.*)
        pathType: ImplementationSpecific
      - backend:
          service:
            name: error-page
            port:
              number: 80
        path: /api/internal/(.*)
        pathType: ImplementationSpecific