1. Ingress DNS

1.1. Overview

1.1.1. Problem

When running minikube locally, you may want to run your services on an ingress controller so that you don't have to use minikube tunnel or NodePorts to access your services. While NodePort might be okay in a lot of circumstances, an ingress is necessary to test some features. Ingress controllers are great because you can define your entire architecture in something like a helm chart, and all your services will be available.

However, for minikube, there is an additional challenge. Your ingress controller relies on DNS, so local DNS names like myservice.test will have to resolve to your minikube ip. The only real way to do this is to add an entry for every service in your /etc/hosts file. This gets messy for obvious reasons. For each service you are running that each has its own DNS entry, you will need to configure it manually. Even if you automate it, you then need to rely on the host operating system for storing configurations instead of storing them in your cluster. To make it worse, these configurations have to be constantly maintained and updated as services are added, removed, and renamed. I call it the /etc/hosts pollution problem.

1.1.2. Solution

What if you could just access your local services magically without having to edit your /etc/hosts file? Well, now you can. The ingress-dns addon acts as a DNS service that runs inside your Kubernetes cluster. All you have to do is install the service and add the minikube ip as a DNS server on your host machine. Each time the DNS service is queried, an API call is made to the Kubernetes master service for a list of all the ingresses. If a match is found for the name, a response is given with an IP address matching minikube ip. For example, with a minikube ip of and an ingress rule for myservice.test configured in the cluster, a DNS query from the host would produce:

#bash:~$ nslookup myservice.test $(minikube ip)

Non-authoritative answer:
Name:    myservice.test $(minikube ip)

1.2. Installation

  1. Start minikube
minikube start
  1. Enable the addons
minikube addons enable ingress
minikube addons enable ingress-dns
  1. Add the minikube ip as a DNS server

1.3. Linux OS with resolvconf

Update the file /etc/resolvconf/resolv.conf.d/base to have the following contents.

search test
timeout 5

Replace with your minikube ip.

If your Linux OS uses systemctl, run the following commands.

sudo resolvconf -u
systemctl disable --now resolvconf.service

If your Linux OS does not use systemctl, run the following commands.

# TODO add supporting docs for Linux OS that do not use `systemctl`

See https://linux.die.net/man/5/resolver

1.3.1. Linux OS with Network Manager

Network Manager can run integrated caching DNS server - dnsmasq plugin and can be configured to use separate nameservers per domain.

Edit /etc/NetworkManager/NetworkManager.conf and set dns=dnsmasq


Also see dns= in NetworkManager.conf.

Configure dnsmasq to handle .test domain

sudo mkdir /etc/NetworkManager/dnsmasq.d/
echo "server=/test/$(minikube ip)" >/etc/NetworkManager/dnsmasq.d/minikube.conf

Restart Network Manager

systemctl restart NetworkManager.service

Ensure your /etc/resolv.conf contains only single nameserver

cat /etc/resolv.conf | grep nameserver

1.4. MocOS

Create a file in /etc/resolver/minikube-test with the following contents.

domain test
search_order 1
timeout 5

Replace with your minikube ip.

If you have multiple minikube IPs, you must configure a file for each.

See https://www.unix.com/man-page/opendarwin/5/resolver/

Note that the port feature does not work as documented.

1.5. Windows

Open Powershell as Administrator and execute the following.

Add-DnsClientNrptRule -Namespace ".test" -NameServers "$(minikube ip)"

The following will remove any matching rules before creating a new one. This is useful for updating the minikube ip.

Get-DnsClientNrptRule | Where-Object {$_.Namespace -eq '.test'} | Remove-DnsClientNrptRule -Force; Add-DnsClientNrptRule -Namespace ".test" -NameServers "$(minikube ip)"
  1. (optional) Configure in-cluster DNS server to resolve local DNS names inside cluster

Sometimes it's useful to access other applications inside cluster via ingress and by their local DNS name - microservices/APIs/tests. In such case ingress-dns addon should be used by in-cluster DNS server - CoreDNS to resolve local DNS names.

Edit your CoreDNS config

kubectl edit configmap coredns -n kube-system

and add block for your local domain

    test:53 {
            cache 30
            forward .

Replace with your minikube ip.

The final ConfigMap should look like:

apiVersion: v1
  Corefile: |
    .:53 {
        health {
           lameduck 5s
    test:53 {
            cache 30
            forward .
kind: ConfigMap

See https://kubernetes.io/docs/tasks/administer-cluster/dns-custom-nameservers/

1.6. Testing

  1. Add the test ingress

kubectl apply -f https://raw.githubusercontent.com/kubernetes/minikube/master/deploy/addons/ingress-dns/example/example.yaml

Note: Minimum Kubernetes version for the example ingress is 1.19

  1. Confirm that DNS queries are returning A records

nslookup hello-john.test $(minikube ip)
nslookup hello-jane.test $(minikube ip)
  1. Confirm that domain names are resolving on the host OS

ping hello-john.test
ping hello-jane.test

Expected results:

PING hello-john.test ( 56 data bytes
64 bytes from icmp_seq=0 ttl=64 time=0.361 ms
PING hello-jane.test ( 56 data bytes
64 bytes from icmp_seq=0 ttl=64 time=0.262 ms
  1. Curl the example server

curl http://hello-john.test
curl http://hello-jane.test

Expected results:

Hello, world!
Version: 1.0.0
Hostname: hello-world-app-557ff7dbd8-64mtv
Hello, world!
Version: 1.0.0
Hostname: hello-world-app-557ff7dbd8-64mtv

1.7. Known issues

1.7.1. .localhost domains will not resolve on chromium

.localhost domains will not correctly resolve on chromium since it is used as a loopback address. Instead use .test, .example, or .invalid

1.7.2. .local is a reserved TLD

Do not use .local as this is a reserved TLD for mDNS and bind9 DNS servers

1.7.3. Mac OS

mDNS reloading

Each time a file is created or a change is made to a file in /etc/resolver you may need to run the following to reload Mac OS mDNS resolver.

sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist

1.8. TODO

  • Add a service that runs on the host OS which will update the files in /etc/resolver automatically
  • Start this service when running minikube addons enable ingress-dns and stop the service when running minikube addons disable ingress-dns

1.9. Contributors

1.10. Images used in this plugin

Image Source Owner
ingress-nginx ingress-nginx Kubernetes ingress-nginx
minikube-ingress-dns minikube-ingress-dns Cryptex Labs
Copyright © 温玉 2021 | 浙ICP备2020032454号 all right reserved,powered by Gitbook该文件修订时间: 2023-02-09 17:32:12

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