plugandtrade/defb repository overview

⁠Defb

A smart default-backend for ingress-nginx⁠

⁠Overview

The default-backed is used when ingress-nginx is not able to route the request to an upstream kuberentes service, coupled with the option customm-http-errors provides the ability for ingress-nginx to pass several HTTP headers down to defb in case of error.

defb uses this information to provide custom error pages, per service, per content-type, instead of one global. In case a service does not have an error configmap defined the global default will be used:

kind: ConfigMap
apiVersion: v1
metadata:
  name: echoserver-error-pages
  namespace: default
  labels:
    app.kubernetes.io/part-of: defb
    app.kubernetes.io/custom-errors: defb
    default-http-backend/alternate-name: echoserver-svc
data:
  5xx.html: |
    <html>
    <body>
        <p>generic html error</p>
    </body>
    </html>
  500.json: |
    {
      "message": "internal server error"
    }
  503.json: |
    {
      "message": "service unavailable"
    }
  5xx.json: |
    {
      "message": "generic json error"
    }

This configmap defines a custom error template for a svc named echoserver-svc in the default namespace.

The following rules apply:

• ANY 500 error where the original request had a Accept header text/html will return the 5xx HTML error.
• 500 error where the original request had a Accept header application/json will return { "message": "internal server error" }
• 503 error where the original request had a Accept header application/json will return { "message": "service unavailable" }
• ANY other 500 error where the original request had a Accept header application/json will return { "message": "generic json error" }

For configuring ingress-nginx to use defb as the default-http-backend see: custom errors⁠

⁠Custom default pages

When there's no error page entry for a service, defb will fallback to /etc/defb/pages (see /pages in this repository). These files can be replaced with your own if you'd like a different fallback pages.

⁠Metrics

Prometheus metrics are exposed on port 3000 /metrics

⁠Developing

⁠Prerequisites

• minikube⁠
• Erlang & Elixir⁠

Minikube or other K8s environment needed.

• Intall dependencies

mix deps.get

• Compile

mix compile

• Running

iex -S mix