Let's consider a python web application deployed under uWSGI via Nginx.
HTTP client ↔ Nginx ↔ Socket/HTTP ↔ uWSGI (web server) ↔ webapp
Where nginx is used as reverse proxy / load balancer.
How to scale this kind of applications in kubernetes? Several options come to my mind: 1. Deploy nginx and uWSGI in a single pod. Simple approach. 2. Deploy nginx + uWSGI in single container? Violate the “one process per container” principle. 3. Deploy only a uWSGI (via HTTP). Omit the usage of nginx.
or there is another solution, involving nginx ingress/load balancer services?
It depends.
I see two scenarios:
Ingress is used
In this case there's no need to have nginx server within the pod, but it can be ingress-nginx which will be balancing traffic across a kubernetes cluster. You can find a good example in this comment on GitHub issue.
No ingress is used.
In this case I'd go with option 1 - Deploy nginx and uWSGI in a single pod. Simple approach.. This way you can easily scale in/out your application and don't have any complicated/unnecessary dependencies.
In case you're not familiar with what ingress is, please find kubernetes documentation - ingress.