Support custom TTLs

[MalteJ]

Especially for k8s services it would be good to be able to set a lower TTL than 300 seconds.
When one node goes down it could take up to five minutes to have an updated DNS.

EDIT
just realized that the load balancer's IP address is used so my argumentation is not valid. Nevertheless a custom TTL would still be a good idea ;)

[linki]

@MalteJ Custom TTLs are on our list and your described use case makes perfect sense, e.g. when running nginx-ingress-controller without a fronting service: https://github.com/linki/external-dns/blob/4d66ac1069164eb952bf8daef13b10ad6f51fa0d/docs/tutorials/nginx-ingress.md#without-a-separate-tcp-load-balancer

[szuecs]

@linki I think we can close this issue, AWS is done, google has an open PR which will be merged soon others can implement as needed

[hjacobs]

@szuecs closing this issue as AWS and Google support are now both in the latest release v0.4.8.