railiance-apps/docs/django-on-railiance.md

Django on Railiance

This is the short recipe for Django workloads running as S5 apps on the Railiance cluster.

Probe Host Header

Production Django usually runs with DEBUG=False and a narrow ALLOWED_HOSTS. Kubelet HTTP probes do not use the public app host by default; they send the pod IP as the Host header. Django rejects that before the request reaches the health view, so kubelet sees HTTP 400 and restarts an otherwise healthy pod.

Set the probe Host header to a value that is also present in ALLOWED_HOSTS:

env:
  ALLOWED_HOSTS: app.example.org,localhost

probes:
  enabled: true
  path: /health/
  port: 8000
  hostHeader: app.example.org

The charts/vergabe-teilnahme chart already renders this as:

httpGet:
  path: /health/
  port: 8000
  httpHeaders:
    - name: Host
      value: app.example.org

When changing the public hostname or ALLOWED_HOSTS, change probes.hostHeader in the same review.

Database URL Secrets

CNPG-generated role passwords may contain URL-reserved characters such as =, +, and /. If the app consumes DATABASE_URL, URL-encode the password when building the env Secret:

make vergabe-db-url-secret

For new charts, prefer either this helper or separate PostgreSQL env vars (POSTGRES_HOST, POSTGRES_USER, POSTGRES_PASSWORD, POSTGRES_DB) so there is no URL parser in the path.