Setup DNS for Kubernetes
c2d-rproxy so we can for example resolve c2platform.org.Categories:
Dnsmasq is used to create a DNS server on c2d-rproxy. See the node configuration in Vagrantfile which has the play plays/mw/dnsmasq.yml. DNS is a secondary function of c2d-rproxy see Setup SOCKS proxy for the two other functions. Typically, this project uses /etc/hosts file to resolve “domain names” see group_vars/all/hosts.yml, except for Kubernetes. For Kubernetes this Dnsmasq-based DNS server is employed. See the GitLab project c2platform/ansible for more information.
Under Construction:
We apologize for the inconvenience, but this page and its subpages are currently under active development.Prerequisites
Setup
export PLAY=plays/mw/dnsmasq.yml # optional
vagrant provision c2d-rproxy1
Verify Dnsmasq
Dnsmasq has been set up to provide DNS service for the c2platform.org domain. This configuration can be found in the group_vars/dnsmasq/main.yml file. Specifically, there is a single wildcard DNS record for c2platform.org that directs to the IP address 1.1.4.205, which essentially means that any subdomain under c2platform.org will resolve to the same IP address.
You can verify that for example with:
dig @1.1.4.205 -p 5353 c2platform.org
dig @1.1.4.205 -p 5353 whatever.c2platform.org
Show me
root@c2d-rproxy1:~# dig @1.1.4.205 -p 5353 c2platform.org
; <<>> DiG 9.11.3-1ubuntu1.18-Ubuntu <<>> @1.1.4.205 -p 5353 c2platform.org
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 54953
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;c2platform.org. IN A
;; ANSWER SECTION:
c2platform.org. 0 IN A 1.1.4.205
;; Query time: 0 msec
;; SERVER: 1.1.4.205#5353(1.1.4.205)
;; WHEN: Thu Mar 23 05:59:52 UTC 2023
;; MSG SIZE rcvd: 59
root@c2d-rproxy1:~#
root@c2d-rproxy1:~# dig @1.1.4.205 -p 5353 whatever.c2platform.org
; <<>> DiG 9.11.3-1ubuntu1.18-Ubuntu <<>> @1.1.4.205 -p 5353 whatever.c2platform.org
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 27200
;; flags: qr aa rd ra ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;whatever.c2platform.org. IN A
;; ANSWER SECTION:
whatever.c2platform.org. 0 IN A 1.1.4.205
;; Query time: 0 msec
;; SERVER: 1.1.4.205#5353(1.1.4.205)
;; WHEN: Thu Mar 23 06:04:21 UTC 2023
;; MSG SIZE rcvd: 68
root@c2d-rproxy1:~#
Configure CoreDNS
With our Dnsmasq-based DNS server running, we can now change CoreDNS pod in Kubernetes to use it. Edit the coredns configmap and configure 1.1.4.205:5353 as our only DNS server ( remove 8.8.8.8 etc ).
kubectl edit configmap coredns -n kube-system # configure 1.1.4.205:5353
microk8s stop && microk8s start
microk8s status --wait-ready
Verify CoreDNS
First we need to find the IP address of the CoreDNS pod and then we can run the dig tests again:
export COREDNS_IP=$(kubectl get pods -n kube-system | grep coredns- | awk '{print $1}' | xargs -I % sh -c 'kubectl get pod % -n kube-system -o jsonpath="{.status.podIP}"')
echo $COREDNS_IP
dig @$COREDNS_IP c2platform.org
dig @$COREDNS_IP whatever.c2platform.org
dig @$COREDNS_IP google.nl
Show me
vagrant@c2d-ks1:~$ dig @$COREDNS_IP c2platform.org
; <<>> DiG 9.18.1-1ubuntu1.3-Ubuntu <<>> @10.1.211.147 c2platform.org
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 47079
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; COOKIE: a1154c86acbeba68 (echoed)
;; QUESTION SECTION:
;c2platform.org. IN A
;; ANSWER SECTION:
c2platform.org. 5 IN A 1.1.4.205
;; Query time: 0 msec
;; SERVER: 10.1.211.147#53(10.1.211.147) (UDP)
;; WHEN: Thu Mar 23 10:44:35 UTC 2023
;; MSG SIZE rcvd: 85
vagrant@c2d-ks1:~$ dig @$COREDNS_IP whatever.c2platform.org
; <<>> DiG 9.18.1-1ubuntu1.3-Ubuntu <<>> @10.1.211.147 whatever.c2platform.org
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 56450
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; COOKIE: 1b2532719222bf31 (echoed)
;; QUESTION SECTION:
;whatever.c2platform.org. IN A
;; ANSWER SECTION:
whatever.c2platform.org. 5 IN A 1.1.4.205
;; Query time: 0 msec
;; SERVER: 10.1.211.147#53(10.1.211.147) (UDP)
;; WHEN: Thu Mar 23 10:45:04 UTC 2023
;; MSG SIZE rcvd: 103
vagrant@c2d-ks1:~$ dig @$COREDNS_IP google.nl
; <<>> DiG 9.18.1-1ubuntu1.3-Ubuntu <<>> @10.1.211.147 google.nl
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 62105
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; COOKIE: ea0bc03c335aa625 (echoed)
;; QUESTION SECTION:
;google.nl. IN A
;; ANSWER SECTION:
google.nl. 30 IN A 142.250.179.163
;; Query time: 0 msec
;; SERVER: 10.1.211.147#53(10.1.211.147) (UDP)
;; WHEN: Thu Mar 23 10:45:23 UTC 2023
;; MSG SIZE rcvd: 75
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