A simple server which allows you to forward dns requests to multiple dns servers (regardless of which are the authoritative servers) and return the first usable response.
This is a small utility which we found useful in our development environments as something which can run locally inside vagrant. It is not recommended to use this in production or any high-load situation.
go get github.com/levenlabs/struggledns
Parameters can be set using (in order of precedence):
- Command line parameters
- Environment variables (e.g.
STRUGGLEDNS_LISTEN_ADDR) - Configuration file (see
--examplecommand line parameter)
struggledns --fwd-to 10.0.0.5:53 --fwd-to 8.8.8.8:53
When a dns request is received using this configuration, struggledns will first
see if the server at 10.0.0.5:53 is alive and returns a dns response with a
non-empty answer section. If so that is returned, otherwise the server at
8.8.8.8:53 will be checked. The order of checking is always in the order the
--fwd-to parameters are specified.
struggledns --fwd-to 10.0.0.5:53,8.8.8.8:53 --fwd-to 10.0.0.6:53,8.8.4.4:53
Each --fwd-to can be a group of comma-delimited addresses to query in
parallel. Every address in a group is queried in parallel and groups are queried
in serial unless --parallel is specified, which causes all sent addresses
from all groups to be queried in parallel. The response still respects the order
of the addresses despite being sent in parallel. In the above example, when a
query is received it will be first sent to both 10.0.0.5:53 and 8.8.8.8:53
and if both of those fail then it will make a request to both 10.0.0.6:53 and
8.8.4.4:53.