Kubernetes NGINX Ingress configmap 301 redirect

Indeed a redirect is possible with a simple annotation:

• nginx.ingress.kubernetes.io/permanent-redirect: https://www.gothereinstead.com
• nginx.ingress.kubernetes.io/from-to-www-redirect: "true"

But as you mentioned, it's "Ingress" wide and not configurable per host, per domain or even per path. So you'll have to do it yourself through the ingress.kubernetes.io/configuration-snippet annotation, which gives you a great deal of power thanks to regular expressions:

kind: Ingress
apiVersion: extensions/v1beta1
metadata:
  name: self-made-redirect
  annotations:
    ingress.kubernetes.io/configuration-snippet: |
      if ($host = 'blog.yourdomain.com') {
        return 301 https://yournewblogurl.com;
      }
      if ($host ~ ^(.+)\.yourdomain\.com$) {
        return 301 https://$1.anotherdomain.com$request_uri;
      }
spec:
  rules:
  - host: ...

If you are not quite used to NGINX, you'll know more about what's possible in the snippet, particularly what is the $host variable right in the NGINX documentation.