COS and TLS

TLS

COS Lite can be deployed unencrypted, with TLS termination only, or end-to-end encrypted.

Unencrypted COS Lite

The cos-lite bundle deploys COS with workloads communicating using plain HTTP (unencrypted).

TLS-terminated COS Lite

The traefik charm can function as a TLS termination point by relating it to an external CA (integrator) charm. Within the COS model, charms would still communicate using plain HTTP (unencrypted).

COS Lite with end-to-end TLS

The cos-lite bundle together with the TLS overlay deploy an end-to-end encrypted COS.

  • COS charms generate CSRs with the k8s fqdn as the SAN DNS and the internal CA signs.
  • All COS charms trust the internal CA by installing the CA certificate in the charm and workload containers, using the update-ca-certificates tool.
  • The external CA provides a certificate for traefik’s external URL.
  • Within the COS model, workloads communicate via k8s fqdn URLs.
  • Requests coming from outside of the model, use the ingress URLs.
  • Traefik is able to establish a secure connection with its proxied apps thanks to trusting the local CA.

Note: currently there is a known issue due to which some COS relations are limited to in-cluster relations only.

The end-to-end COS TLS design is described in the diagram below. The diagram is limited to prometheus and alertmanager for brevity and clarity.


Last updated 4 months ago.