[Pdns-users] Enhancing pdns recursor observability
Peter van Dijk
peter.van.dijk at netherlabs.nl
Mon May 13 14:49:45 UTC 2013
On May 13, 2013, at 12:11 , Thomas Mieslinger wrote:
> To be able to understand these problems in a live system I would like to have some sort of tracing facility in pdns_recursor which can be turned on and off without restarting the service.
> Ideally pdns_recursor would provide some sort of cli which can be used to create output channels, create, list and delete filters.
Have you seen 3.5s trace-regex?
[vagrant at pdns ~/pdns/pdns (master)⚡]$ sudo ./rec_control trace-regex '95\.194\.in-addr\.arpa'
[vagrant at pdns ~/pdns/pdns (master)⚡]$ dig -x 220.127.116.11
... answer follows
meanwhile on my recursor (running in a terminal, in the foreground):
May 13 16:44:59 0  question for '18.104.22.168.in-addr.arpa.|PTR' from 127.0.0.1
May 13 16:45:00  22.214.171.124.in-addr.arpa.: Looking for CNAME cache hit of '126.96.36.199.in-addr.arpa.|CNAME'
May 13 16:45:00  188.8.131.52.in-addr.arpa.: No CNAME cache hit of '184.108.40.206.in-addr.arpa.|CNAME' found
May 13 16:45:00  220.127.116.11.in-addr.arpa.: No cache hit for '18.104.22.168.in-addr.arpa.|PTR', trying to find an appropriate NS record
... 830 more lines of debugging
May 13 16:46:51  2.0-22.214.171.124.in-addr.arpa.: status=got results, this level of recursion done
> Has anyone else sometimes the need to dive deeply into how the recursor is working and which server in the outside world are failing?
Yes, this is a very real need. We always welcome suggestions for improving the recursor in this area.
> Is this idea worth opening a wishlist ticket?
Your idea is very big, and it is hard to say whether it would get picked up as a whole. If you can split it up, perhaps pointing out specific things you miss in our current trace(-regex) functionality, this would help us improve the recursor in smaller steps.
I like your idea, though!
Peter van Dijk
Netherlabs Computer Consulting BV - http://www.netherlabs.nl/
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