Replace caddy with traefik.

[boehlke]

No description provided.

[peb-adr]

I have reviewed, tested and adjusted this PR.
My current work is on
https://github.com/peb-adr/openslides-proxy/tree/traefik

ATM it looks like I cannot update this PR because I have no permission to push to kryptance:main.

@rrenkert

---

The following notes I took explaining the changes I made.

• only need ./templates/traefik.yml

  • -> delete./traefik.yml it will be generated by entrypoint.sh

• Biggest change is to support plain/cleartext HTTP

  • Needed in order to make possible to operate behind another proxy taking care of cert handling
  • -> common practice, especially when administering many services and taking care of many domains/certs uniformly

• main entryPoint renamed to main from websecure since it can take different configurations regarding TLS

  • -> If there is a big desire to follow name convention for web/websecure this naming would need to be done conditionally like the actual settings
  • -> For now it seemed easier to me to just have it one name

• Add env vars

  • ENABLE_DASHBOARD
    • we don't want (and certainly not with debug: true hardcoded) dashboard active by default in prod
    • maybe if in the future we want it in prod, debug must be made configurable as well
  • ENABLE_AUTO_HTTPS
    • see readme
  • EXTERNAL_ADDRESS
    • see readme
  • ACME_ENDPOINT
    • see readme
  • ACME_EMAIL
    • see readme

• *_HOST and *_PORT variables default values were set in multiple places

  • -> reduced to just one

• entrypoint.sh

  • set -a makes all export statements obsolete and the script more readable
  • make entryPoints definition(s) dynamic to support different tls modes
  • Rework for-loop for assembling routing configuration towards openslides-services
    • No hardcoded service list , instead find services/*.service files
      • -> will make addition/removal of services more straightforward in the future

• TODO:
  • entrypoint -> entrypoint.sh
  • make auto-https work as described in main:README.md
  • understand and be clear about when we want to fallback to traefik's default certStore and when not
    • -> consider when TLS SNI is available for this

[peb-adr]

From the last TODOs only one is remaining:

• understand and be clear about when we want to fallback to traefik's default certStore and when not
  • -> consider when TLS SNI is available for this

I'll create a separate issue for this, as it's not super pressing ATM.

This PR is ready for merge now.