Install

$ shards install
$ shards update
$ crystal build razor.cr --release --no-debug

Testing with docker

sudo ./docker/tests.sh

Building binary with docker

sudo ./docker/build.sh

Redis records

Zone setup

HMSET node1.route.example.app.io:CONFIG SOA ...
HMSET node1.route.example.app.io:CONFIG TTL 3600
HMSET node1.route.example.app.io:CONFIG NS ns1.example.org,ns2.example.org

Random

SADD node1.route.example.app.io:A 1.1.1.1 2.2.2.2 3.3.3.3
SADD node1.route.example.app.io:AAAA 2001::1 2001::2 2001::3

Consistent Hashing

HMSET node1.route.example.app.io:CONFIG ANSWER consistent_hash
SADD node1.route.example.app.io:A 1.1.1.1 2.2.2.2 3.3.3.3
SADD node1.route.example.app.io:AAAA 2001::1 2001::2 2001::3

Group Consistent hashing

HMSET node1.route.example.app.io:CONFIG ANSWER group_consistent_hash
SADD node1.route.example.app.io:GROUPS GROUP1 GROUP2
SADD GROUP1:A 192.168.1.1 192.168.1.2
SADD GROUP2:A 192.168.2.1 192.168.2.2
SADD GROUP1:AAAA 2001::1 2001::2
SADD GROUP2:AAAA 2002::1 2002::2

GeoIP

This setup requires setting zone in razor.json to be like in this routes.example.org:

HMSET routes.example.org:CONFIG ANSWER geoip
HMSET routes.example.org:CONFIG SOA ...
HMSET routes.example.org:CONFIG TTL 3600
SADD routes.example.org:A 10.0.0.1 10.0.0.2
SADD routes.example.org:AAAA 2a02::1 2a02::2
SADD node1.route.example.app.io:A 1.1.1.1 2.2.2.2
SADD node1.route.example.app.io:AAAA 2001::1 2001::2
SADD node2.route.example.app.io:A 192.168.0.1 192.168.0.2
SADD node2.route.example.app.io:AAAA 2a02:4780::1 2a02:4780::2
SET geoip🇪🇺lt node1.route.example.app.io
SET geoip:eu node2.route.example.app.io

Specifying IPv4/IPv6 ranges instead of plain hosts

You can specify the whole range like:

SADD routes.example.org:A 192.168.1.0/24 192.168.2.0/24
SADD routes.example.org:AAAA 2a02:4780:1::/48 2a02:4780:2::/48

And the Razor automatically picks up a random IPv4/IPv6 address from those ranges.

Current limitation is that IPv4 subnet MUST be /24, and IPv6 /48.

With this feature, you also have the ability to skip some specific hosts from being returned by Razor to the client. It's called SKIPLIST. You define:

SADD example.org:A:SKIPLIST 192.168.1.100 192.168.2.255
SADD example.org:AAAA:SKIPLIST 2a02:4780:1💯:/64 2a02:4780:2:255::/64

Skip lists work by checking /32 for IPv4, and /64 for IPv6 addresses.

In this example, if the Razor picks the random IPv6 from 2a02:4780:2::/48, and 2a02:4780:2:255::/64 is defined as a skip-list item, then Razor picks another one that is not blocklisted.

Tests

# dnsperf -d data -n 10000
DNS Performance Testing Tool
Nominum Version 2.0.0.0

Statistics:

  Queries sent:         40000
  Queries completed:    40000 (100.00%)
  Queries lost:         0 (0.00%)

  Response codes:       NOERROR 40000 (100.00%)
  Average packet size:  request 27, response 49
  Run time (s):         0.551791
  Queries per second:   72491.214971

  Average Latency (s):  0.001175 (min 0.000487, max 0.011503)
  Latency StdDev (s):   0.000560