如何将流量从主机名重定向到 Kubernetes (AKS) 中的自定义 IP 地址？

Question

I'm following this tutorial: https://kubernetes.io/docs/concepts/services-networking/add-entries-to-pod-etc-hosts-with-host-aliases/

But it seems not to be working even though when I run cat /etc/hosts inside the pod I can see my hostname there. Is there any other way of achieving this? I also tried with kube-dns, but that will just redirect the traffic to custom DNS server IP rather than normal server IP?

I have a service with a single pod where I would like to rewire one hostname to go to a custom IP address for testing purposes.

nslookup gives:

root@manager-admin-5944869775-x59n5:/app# nslookup xxxxx.azure-devices.net
Server:         10.0.0.10
Address:        10.0.0.10#53

Non-authoritative answer:
xxxxx.azure-devices.net        canonical name = ihsu-prod-bl-004.cloudapp.net.
Name:   ihsu-prod-bl-004.cloudapp.net
Address: 137.117.83.38

While hosts are:

root@manager-admin-5944869775-x59n5:/app# cat /etc/hosts
# Kubernetes-managed hosts file.
127.0.0.1       localhost
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
fe00::0 ip6-mcastprefix
fe00::1 ip6-allnodes
fe00::2 ip6-allrouters
10.244.2.104    manager-admin-5944869775-x59n5
40.84.159.16 xxxxx.azure-devices.net

Any ideas or help?

Answer 1

That should work...Anyway its not a best practice as you probably know...

Anyway, try first if you have connectivity to the IP "telnet 40.84.159.16 80" (You will have to install telnet if you don't have it, and if 80 is the port you want call). It could be for example a firewall issue on the outbound connectivity of the cluster or the incoming connections from your service you are trying to connect.

However if you can't...Try to use core-dns as you mentioned with the Host Plugin.

And as a last resort you can specify on a Pod a DNS nameserver which modifies the /etc/resolv.conf file of the pod (You ccould do that with CoreDNS too).

Of course this last approach relies you can modify your DNS entries, and that you will not have any DNS conflict, which most sure will appear...

apiVersion: v1
kind: Pod
metadata:
  namespace: default
  name: dns-example
spec:
  containers:
    - name: test
      image: nginx
  dnsPolicy: "None"
  dnsConfig:
    nameservers:
      - 1.2.3.4
    searches:
      - ns1.svc.cluster-domain.example
      - my.dns.search.suffix
    options:
      - name: ndots
        value: "2"
      - name: edns0