external-dns/docs/ttl.md
Igor Zibarev 6e6af8aa0d Add support for human-friendly TTL values
Supports specifying TTL values in Golang duration format for
`external-dns.alpha.kubernetes.io/ttl` annotation.
2020-01-09 21:13:53 +03:00

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Configure DNS record TTL (Time-To-Live)
=======================================
An optional annotation `external-dns.alpha.kubernetes.io/ttl` is available to customize the TTL value of a DNS record.
TTL is specified as an integer encoded as string representing seconds.
To configure it, simply annotate a service/ingress, e.g.:
```yaml
apiVersion: v1
kind: Service
metadata:
annotations:
external-dns.alpha.kubernetes.io/hostname: nginx.external-dns-test.my-org.com.
external-dns.alpha.kubernetes.io/ttl: "60"
...
```
TTL can also be specified as a duration value parsable by Golang [time.ParseDuration](https://golang.org/pkg/time/#ParseDuration):
```yaml
apiVersion: v1
kind: Service
metadata:
annotations:
external-dns.alpha.kubernetes.io/hostname: nginx.external-dns-test.my-org.com.
external-dns.alpha.kubernetes.io/ttl: "1m"
...
```
Both examples result in the same value of 60 seconds TTL.
TTL must be a positive value.
Providers
=========
- [x] AWS (Route53)
- [ ] Azure
- [ ] Cloudflare
- [x] DigitalOcean
- [x] Google
- [ ] InMemory
- [x] Linode
- [x] TransIP
- [x] RFC2136
PRs welcome!
Notes
=====
When the `external-dns.alpha.kubernetes.io/ttl` annotation is not provided, the TTL will default to 0 seconds and `enpoint.TTL.isConfigured()` will be false.
### AWS Provider
The AWS Provider overrides the value to 300s when the TTL is 0.
This value is a constant in the provider code.
### DigitalOcean Provider
The DigitalOcean Provider overrides the value to 300s when the TTL is 0.
This value is a constant in the provider code.
### Google Provider
Previously with the Google Provider, TTL's were hard-coded to 300s.
For safety, the Google Provider overrides the value to 300s when the TTL is 0.
This value is a constant in the provider code.
For the moment, it is impossible to use a TTL value of 0 with the AWS, DigitalOcean, or Google Providers.
This behavior may change in the future.
### Linode Provider
The Linode Provider default TTL is used when the TTL is 0. The default is 24 hours
### TransIP Provider
The TransIP Provider minimal TTL is used when the TTL is 0. The minimal TTL is 60s.