How can I configure path-based routing for my local Knative service?

Below is some guidance on how to move toward your desired behavior of using simple URLs (e.g.
  http://localhost:32198/hello-world) without having to send a custom Host header on each request.

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1. Understand Knative’s Default Routing

By default, Knative (with Kourier as the ingress) routes traffic based on the Host header. When you deploy a Knative Service, it is assigned a domain (often something like "hello-world.default.example.com") and the ingress controller (Kourier) matches incoming requests using that host name. That’s why you need to issue a request like:

BASHCopied
curl -H "Host: hello-world.default.svc.cluster.local" http://localhost:32198

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2. Changing to a Custom Domain

To avoid passing the Host header manually, you have a couple of options:

• Update the Default Domain Config
  Knative uses a ConfigMap (usually named config-domain in the knative-serving namespace) that specifies which domains Knative will serve. By editing this ConfigMap, you can have Knative assign your service a domain that matches what you want. For example, you might want to map the empty host ("") or another simple name to your service.

  To inspect the current domain configuration:

  BASHCopied
  kubectl get configmap config-domain -n knative-serving -o yaml

  Then, you could update it so that requests to, say, localhost or another custom domain (like hello-world) are handled automatically. (Note that if you use a custom domain, you’ll have to resolve it—commonly by adding an entry to your /etc/hosts file.)

• Leverage /etc/hosts for Local Testing
  If you update your config-domain so that your service domain is something like hello-world.local, add a corresponding mapping in your /etc/hosts file:

  NONECopied
  127.0.0.1 hello-world.local

  Then you could simply run:

  BASHCopied
  curl http://hello-world.local

  And the ingress will see the correct Host header.

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3. Achieving Path-Based Routing

Knative’s built-in routing is based on host matching—it does not by default perform path-based routing (for example, matching /hello-world regardless of hostname).

To have URLs such as:

BASHCopied
curl http://localhost:32198/hello-world

work directly, consider these approaches:

• Use an External API Gateway or Reverse Proxy
  Place a reverse proxy (such as Nginx or Traefik) in front of your cluster. This proxy can do path-based routing by rewriting the request (for example, setting the Host header to the Knative service’s domain) before forwarding it to your ingress endpoint.
  Such a proxy can listen on the required port and route /hello-world to your Knative service while leaving other paths unaffected.

• Custom Ingress Configurations (if supported by your ingress)
  Some ingress implementations or additional configuration options in Kourier might allow for request rewriting or path-based matching. However, this is more advanced and not part of the default Knative behavior.

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Summary

Even though you would like to have a simple URL such as http://localhost:32198/hello-world, Knative serving with Kourier uses host-based rules out of the box. The two main strategies are:

1. Adjust the Knative domain: Configure the config-domain ConfigMap so that your service has a simple domain, and ensure your system (e.g. via /etc/hosts) resolves that domain correctly.
2. Add an intermediary proxy/gateway: Use a reverse proxy that accepts path-based URLs and rewrites them into the required host-based requests for Knative.

These approaches will allow you to test and work with your functions using simpler URLs. For more details on domain configuration and ingress setup with Knative, check out the official Knative Serving documentation.