Cache prefilling

This module provides ability to periodically prefill DNS cache by importing root zone data obtained over HTTPS.

Intended users of this module are big resolver operators which will benefit from decreased latencies and smaller amount of traffic towards DNS root servets.

Example configuration is:

modules.load('prefill')
prefill.config({
      ['.'] = {
              url = 'https://www.internic.net/domain/root.zone',
              interval = 86400  -- seconds
              ca_file = '/etc/pki/tls/certs/ca-bundle.crt', -- optional
      }
})

This configuration downloads zone file from URL https://www.internic.net/domain/root.zone and imports it into cache every 86400 seconds (1 day). The HTTPS connection is authenticated using CA certificate from file /etc/pki/tls/certs/ca-bundle.crt and signed zone content is validated using DNSSEC.

Root zone to import must be signed using DNSSEC and the resolver must have valid DNSSEC configuration.

Parameter	Description
ca_file	path to CA certificate bundle used to authenticate the HTTPS connection (optional, system-wide store will be used if not specified)
interval	number of seconds between zone data refresh attempts
url	URL of a file in RFC 1035 zone file format

Only root zone import is supported at the moment.

Dependencies

Depends on the prefill-lua-http and luafilesystem libraries.