DNSMasq for Testing Cloud Setups¤

!!! quote "OpenShift Provisining"

That said, DNS is extremely important to the success of the OpenShift 4 installer. Pay close
attention to the records you create and verify each one before installation, especially the
first time.

!!! quote "Prerequisites Terraform on DO"

- A personal domain pointed to DigitalOcean’s nameservers. See How To Point to DigitalOcean
  Nameservers From Common Domain Registrars or How to Add Domains using DigitalOcean’s Control
  Panel.
- Note: Use your own, unique domain name or Terraform will be unable to deploy the DNS
  resources. Be sure your domain is pointed to DigitalOcean nameservers.

DNS is in many cases a practical and simple solution for cluster internal service routing.

But Cloud Infrastructure Providers and even container orchestrators, in many cases, want to also own resolution of external DNS queries, for the resources run on their Infrastructure.

Registered propagated domains are a time and resource bottleneck, when you think about many developers working on the same codebases, which is to be deployed and tested by them, CI/CD and so on.

On AWS you have Route53 for quick test DNS services but a more generic approach is to use dnsmasq on the test machines.

In dnsmasq, you can do:

address=/myfakedomain.com/10.16.1.20

to redirect queries for myfakedomain.com to the IP address specified. You can even do things like:

address=/plex/10.16.1.55

Basic Setup¤

`bash ~ ❯ cat /etc/dnsmasq.d/tftest.net no-dhcp-interface=enp56s0u1u2i5 bogus-priv domain=tftest.net expand-hosts # not works for me: #addn-hosts=/home/gk/tfhosts local=/tftest.net/ domain-needed no-resolv no-poll server=8.8.8.8 server=8.8.4.4

and

~ ❯ cat /etc/hosts 127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6 10.0.0.30   hp
10.0.0.84   gk 10.0.0.1    fritz

````

Then `systemctl restart dnsmasq`

You get resolution then:

```bash ~ ❯ nslookup gk 127.0.0.1 Server:     127.0.0.1 Address:    127.0.0.1#53

Name:   gk Address: 10.0.0.84

~ ❯ nslookup gk.tftest.net 127.0.0.1 Server:     127.0.0.1 Address:    127.0.0.1#53

Name:   gk.tftest.net Address: 10.0.0.84

and with

`bash ~ ❯ sudo systemd-resolve --set-dns 127.0.0.1 --interface=enp56s0u1u2i5 [sudo] password for gk: this also works:

~ ❯ ping gk.tftest.net PING gk.tftest.net (10.0.0.84) 56(84) bytes of data.

Forwarding¤

Now configure

address=/tftest.net/<ip of cloud provider's dns>

and they'll get the resolution requests.

Reminder: To try those DNS servers w/o DNS mask: dig @ns1.digitalocean.com host1.mytest.com If that works you can do the above.

Resources:¤

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