Kubernetes is a lot of fun and also a maze of settings and services. When working on your Ingress rules, it's good to have something on the inside to validate your configuration. Echo service to the rescue!

Example

Imagine you've got a bunch of services in your cluster, sharing a common base path (in this case /api/echo). And you've got ingress in place to manage routing. To see "what gets through" is especially useful when you're using Ingress' URL rewriting. Just to make sure that your regexes are correct. How do you check that?

$ curl "https://<your-host>/api/echo/some/demo?thingy=Y"

By running this command line curl request, you can see that the rewrite rule transforms it to the path in line 3 (stripping /api/echo from the path).

Request served by echo-deployment-8475b5cddd-bzg7v

HTTP/1.1 GET /some/demo?thingy=Y

Host: <your-host>
Accept: */*
X-Real-Ip: 10.240.0.4
X-Forwarded-For: 10.240.0.4
X-Forwarded-Host: &lt;your-host>
X-Forwarded-Port: 443
X-Forwarded-Proto: https
X-Original-Uri: /api/echo/some/demo?thingy=Y
X-Request-Id: 3822dd5ca8545c3222544392d692f212
X-Scheme: https
User-Agent: curl/7.54.0

The service just returns a response containing as much as it could gather from your request.

Deployment

I used this echo-server and configured a simple deployment for it:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: echo-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: echo-server
  template:
    metadata:
      labels:
        app: echo-server
    spec:
      containers:
        - name: echo-server
          image: jmalloc/echo-server
          ports:
            - name: http-port
              containerPort: 8080
---
apiVersion: v1
kind: Service
metadata:
  name: echo-service
spec:
  ports:
    - name: http-port
      port: 80
      targetPort: http-port
      protocol: TCP
  selector:
    app: echo-server

Some ingress rules to test

Next, we need some rules including rewrites to test stuff. I won't go into the details of that, there's enough examples out there. Just add one rewrite rule for your echo service, matching the other rules, and you've got a working setup.

          - path: /api/echo/?(.*)
            backend:
              serviceName: echo-service
              servicePort: 80

Now, when you run the curl command from the start of this post, it should answer correctly!