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DNSEntry Translation into DNS records

Creating A and/or AAAA records

To create an A and/or AAAA DNS records, the spec of the DNSEntry must contains a list of IP addresses as targets.

Example:

apiVersion: dns.gardener.cloud/v1alpha1
kind: DNSEntry
metadata:
  name: myentry-a
  namespace: default
spec:
  dnsName: "myentry-a.my-own-domain.com"
  targets:
  - 1.2.3.4
  - 1.2.3.5
  - 2abc:1234:5678::42
  ttl: 600 # optional to set TTL

Two DNS records are created, as can be checked with nslookup:

$ nslookup -type=A myentry-a.my-own-domain.com
...
Non-authoritative answer:
Name:	myentry-a.my-own-domain.com
Address: 1.2.3.4
Name:	myentry-a.my-own-domain.com
Address: 1.2.3.5

$ nslookup -type=AAAA myentry-a.my-own-domain.com
...
Non-authoritative answer:
myentry-a.dnstest.my-own-domain.com	has AAAA address 2abc:1234:5678::42

Creating a CNAME record

To create a CNAME DNS record, the target list of the DNSEntry must contain exactly one domain name.

Example:

apiVersion: dns.gardener.cloud/v1alpha1
kind: DNSEntry
metadata:
  name: myentry-cname
  namespace: default
spec:
  dnsName: "myentry-cname.my-own-domain.com"
  targets:
  - mytarget.my-own-domain.com
  ttl: 600 # optional to set TTL

A CNAME DNS record is created as expected:

$ nslookup -type=CNAME myentry-cname.my-own-domain.com
...
Non-authoritative answer:
myentry-cname.my-own-domain.com	canonical name = mytarget.my-own-domain.com.

Creating TXT record

To create a TXT DNS record, the texts list of the DNSEntry contains the text values.

Example:

apiVersion: dns.gardener.cloud/v1alpha1
kind: DNSEntry
metadata:
  name: myentry-txt
  namespace: default
spec:
  dnsName: "myentry-txt.my-own-domain.com"
  text:
  - "first value"
  - "second value"
  ttl: 600 # optional to set TTL

TXT DNS records are created as expected:

$ nslookup -type=TXT myentry-txt.my-own-domain.com
...
Non-authoritative answer:
  myentry-txt.my-own-domain.com	text = "first value"
  myentry-txt.my-own-domain.com	text = "second value"

Creating A/AAAA records for multiple domain names

This is a feature to provide a CNAME like behaviour for multiple domain names. The .spec.targets list of the DNSEntry contains multiple DNS names in this case. These names are looked up periodically and resolved into their IPv6 an IPv4 addresses.

Example:

apiVersion: dns.gardener.cloud/v1alpha1
kind: DNSEntry
metadata:
  name: myentry-multi-cname
  namespace: default
spec:
  dnsName: "myentry-multi-cname.my-own-domain.com"
  targets:
  - wikipedia.org
  - wikipedia.de
  ttl: 600 # optional to set TTL
  cnameLookupInterval: 200 # optional to specify lookup internal to resolve the DNS names

As wikipedia.org resolves to 185.15.59.224 and 2a02:ec80:300:ed1a::1 and wikipedia.de to 49.13.55.174 and 2a01:4f8:c012:3f0a::1 (at time of running this example), you will get these A and AAAA DNS records:

$ nslookup -type=A myentry-multi-cname.my-own-domain.com
...
Non-authoritative answer:
Name:	myentry-multi-cname.my-own-domain.com
Address: 185.15.59.224
Name:	myentry-multi-cname.my-own-domain.com
Address: 49.13.55.174

$ nslookup -type=AAAA myentry-multi-cname.my-own-domain.com
...
Non-authoritative answer:
myentry-multi-cname.my-own-domain.com	has AAAA address 2a02:ec80:300:ed1a::1
myentry-multi-cname.my-own-domain.com	has AAAA address 2a01:4f8:c012:3f0a::1

Note

Using this feature creates reoccuring work load on the dns-controller-manager as the target domain names need to be looked up periodically. If the target addressed have changed, the addresses in the created A/AAAA records will be updated automatically. As two more steps are involved, some additional time is needed until your DNS clients will see such changes in comparison with setting the addresses directly as targets. The scheduled DNS lookups happen roughly at the set intervals, but timing depends on cluster load and upstream DNS responsiveness. Also be aware that this feature can only be used for domain names visible to the dns-controller-manager.

Creating A/AAAA records for single domain name

This is a special feature to avoid a CNAME record and resolving the domain name into addresses. The .spec.targets list of the DNSEntry contains a single DNS name in this case. These name is looked up periodically and resolved into its current IPv6 an IPv4 addresses.

Example:

apiVersion: dns.gardener.cloud/v1alpha1
kind: DNSEntry
metadata:
  name: myentry-no-cname
  namespace: default
spec:
  dnsName: "myentry-no-cname.my-own-domain.com"
  targets:
  - wikipedia.org
  resolveTargetsToAddresses: true # this field is needed to distinguish from CNAME record creation
  ttl: 600 # optional to set TTL
  cnameLookupInterval: 200 # optional to specify lookup internal to resolve the DNS names

As wikipedia.org resolves to 185.15.59.224 and 2a02:ec80:300:ed1a::1 (at time of running this example), you will get these A and AAAA DNS records:

$  nslookup -type=A myentry-no-cname.my-own-domain.com
...
Non-authoritative answer:
Name:	myentry-no-cname.my-own-domain.com
Address: 185.15.59.224

$ nslookup -type=AAAA myentry-no-cname.my-own-domain.com
...
Non-authoritative answer:
myentry-no-cname.my-own-domain.com	has AAAA address 2a02:ec80:300:ed1a::1

Note

Using this feature creates reoccuring work load on the dns-controller-manager as the target domain names need to be looked up periodically. If the target addressed have changed, the addresses in the created A/AAAA records will be updated automatically. As two more steps are involved, some additional time is needed until your DNS clients will see such changes in comparison with setting the addresses directly as targets. The scheduled DNS lookups happen roughly at the set intervals, but timing depends on cluster load and upstream DNS responsiveness. Also be aware that this feature can only be used for domain names visible to the dns-controller-manager.