CODEWITHSUNDEEP
dockerkubernetesdnsknativeknative-serving
cboettig
cboettig

Reputation: 12707

Obtaining a public IP or domain name in a Knative+MiniKube setup

I am attempting to use knative to self-host a simple FaaS platform from an on-premises Linux server. I have installed minikube successfully, and installed/configured knative using the knative operator.

Following the default selection in the linked guide, I have set up kourier as the networking layer and selected Magic DNS (sslip.io) setup. After running minikube tunnel, I can successfully serve demo apps like helloworld-python.

However, my "External IP" according to KNative is a private-ip:

kubectl --namespace knative-serving get service kourier

NAME      TYPE           CLUSTER-IP      EXTERNAL-IP     PORT(S)                      AGE
kourier   LoadBalancer   10.100.195.53   10.100.195.53   80:31140/TCP,443:31175/TCP   15h

(Note the IP starts with 10., this IP is not external to the machine.)

As such, the apps return sslip.io addresses containing this private IP: http://helloworld-python.default.10.100.195.53.sslip.io. As a result, I can query this service (e.g. via curl) just fine from the host server, but I can't access the service from any other machine. Likewise, if I attempt to configure any "Eventing" services, KNative produces webhooks with a private IP address, which obviously don't work since external services like GitHub don't resolve them.

So, why does Knative return a private IP in this setting? The KNative installation doesn't seem to give any indication that this will be the case, suggesting that

kubectl --namespace knative-serving get service kourier

might return a CNAME or an IP address and that we should "note this for DNS configuration later" (except if using Magic DNS). Should it be returning a private IP?

As a side-note/ background context, my server has a fixed IP address, I use caddy (in container on the same docker network as minikube) to provide https domain names to services. Also, outside of knative, if I just follow standard minikube guide to make a service as NodePort or LoadBalancer, I can easily take the port that kubectl get svc shows, and expose the service in caddy by pointing to said port on the minikube container, something like this in the Caddyfile:

minikube.app.mydomain.com {
  reverse_proxy minikube:32637 {
    header_up Host {host}
  } 
}

This is just to confirm that in vanilla minikube I have no trouble with ingress configuration. KNative clearly has this extra layer of networking by which it's generating URLs for applications though and that has be flummoxed. I can't just replace the `minikube:32637 with the private IP addresses KNative returns)

Upvotes: 1

Views: 632

Answers (1)

E. Anderson
E. Anderson

Reputation: 3493

Knative uses the HTTP Host header to share a single IP address across many services (sorta like what you're doing with caddy...).

If you want to use caddy to route these requests, you'll need to rewrite the Host header using the header_up directive. You may be able to use the replacement form and/or change the Knative domain prefix to make this easier.

Upvotes: 1

Related Questions