Files
coredns/plugin/clouddns/README.md
Aradhya Jain 538c3554bc plugin/clouddns: add refresh directive (#8616)
Brings clouddns to parity with route53, which already exposes a
refresh directive to control how often zones are re-synced. clouddns
currently hardcodes this to 1 minute (delay := 1 * time.Minute in Run)
with no way to change it.

Adds a refresh field to the CloudDNS struct, threads it through New(),
and has Run() use h.refresh instead of the hardcoded delay. Parses the
refresh directive in setup() mirroring route53's exact validation
(accepts a plain number as seconds or a duration string, must be
greater than 0).

Extends TestSetupCloudDNS with refresh coverage (valid duration, valid
plain number, missing arg, non-numeric, zero, negative). Verified it
fails without the setup.go change (unknown property error) and passes
with it.

Signed-off-by: stackedbyaradhya <aradhyaj736@gmail.com>
2026-10-08 18:47:32 -07:00

93 lines
3.6 KiB
Markdown

# clouddns
## Name
*clouddns* - enables serving zone data from GCP Cloud DNS.
## Description
The *clouddns* plugin is useful for serving zones from resource record
sets in GCP Cloud DNS. This plugin supports all [Google Cloud DNS
records](https://cloud.google.com/dns/docs/overview#supported_dns_record_types). This plugin can
be used when CoreDNS is deployed on GCP or elsewhere. Note that this plugin accesses the resource
records through the Google Cloud API. For records in a privately hosted zone, it is not necessary to
place CoreDNS and this plugin in the associated VPC network. In fact the private hosted zone could
be created without any associated VPC and this plugin could still access the resource records under
the hosted zone.
## Syntax
~~~ txt
clouddns [ZONE:PROJECT_ID:HOSTED_ZONE_NAME...] {
credentials [FILENAME]
fallthrough [ZONES...]
refresh DURATION
}
~~~
* **ZONE** the name of the domain to be accessed. When there are multiple zones with overlapping
domains (private vs. public hosted zone), CoreDNS does the lookup in the given order here.
Therefore, for a non-existing resource record, SOA response will be from the rightmost zone.
* **PROJECT\_ID** the project ID of the Google Cloud project.
* **HOSTED\_ZONE\_NAME** the name of the hosted zone that contains the resource record sets to be
accessed.
* `credentials` is used for reading the credential file from **FILENAME** (normally a .json file).
This field is optional. If this field is not provided then authentication will be done automatically,
e.g., through environmental variable `GOOGLE_APPLICATION_CREDENTIALS`. Note that CoreDNS validates that the given
file has a valid credentials type, but does not validate the credentials file for malicious input. Please see
Google Cloud's [authentication method](https://cloud.google.com/docs/authentication) and
[validating credential configurations from external sources](https://docs.cloud.google.com/docs/authentication/client-libraries#external-credentials) for more details.
* `fallthrough` If zone matches and no record can be generated, pass request to the next plugin.
If **[ZONES...]** is omitted, then fallthrough happens for all zones for which the plugin is
authoritative. If specific zones are listed (for example `in-addr.arpa` and `ip6.arpa`), then
only queries for those zones will be subject to fallthrough.
* `refresh` can be used to control how long between record retrievals from Cloud DNS. It requires
a duration string as a parameter to specify the duration between update cycles. Each update
cycle may result in many Cloud DNS API calls depending on how many domains use this plugin and
how many records are in each. Adjusting the update frequency may help reduce the potential of
API throttling by Google Cloud. If not provided the default refresh is 1 minute.
## Examples
Enable clouddns with implicit GCP credentials and resolve CNAMEs via 10.0.0.1:
~~~ txt
example.org {
clouddns example.org.:gcp-example-project:example-zone
forward . 10.0.0.1
}
~~~
Enable clouddns with fallthrough:
~~~ txt
example.org {
clouddns example.org.:gcp-example-project:example-zone example.com.:gcp-example-project:example-zone-2 {
fallthrough example.gov.
}
}
~~~
Enable clouddns with multiple hosted zones with the same domain:
~~~ txt
. {
clouddns example.org.:gcp-example-project:example-zone example.com.:gcp-example-project:other-example-zone
}
~~~
Enable clouddns and refresh records every 3 minutes:
~~~ txt
example.org {
clouddns example.org.:gcp-example-project:example-zone {
refresh 3m
}
}
~~~