Is it possible to create health check based on DNS response value with DNS dist

[LukeR97]

Hello,

I am currently evaluating if PowerDNS DNS dist can solve a problem I am working on. Essentially I am looking to figure out if it is possible to create a health check within DNS dist that could potentially mark a server as UP or DOWN depending on the value returned by a configured DNS record. So if I wanted a health check that looks at a DNS record and expects a defined value say 1.2.3.4 , if I don't get that response from DNS then the server should be marked as DOWN until the expected value is returned again.

Eg
check against dummy.tld -> 1.2.3.4 ✅
check against dummy.tld -> 4.5.6.7 or NXDOMAIN / SERVFAIL etc ❌

I know that this request may come across as a little strange/vague but there is a reason why simply using mustResolve=true or checking if the server itself responds is not enough.

From what I have read, there is no direct way of achieving what I am trying to do, but it would be nice to know if this might be possible to do in Lua before I put some time into learning Lua.

Thank you

[rgacogne]

This is currently not possible because there is no way to let a Lua function decide whether a given health-check response is valid or not. I think what you want is described in #15062 but no-one has implemented it yet.