Nssync: Synchronization Block

4.3 Synchronization Block

A synchronization block defines a set of zones to be synchronized from the database and configures SQL statements which return the zone data. This set is identified by synchronization tag, supplied as the argument to the sync statement:

# Define a synchronization block.
sync tag {
  # zone configuration file
  zone-conf pat;
  # pattern for new zone file names
  zonefile-pattern pat;
  # add these statements to each generated zone file
  add-statements text;
  # a query for retrieving SOA records
  soa-query string;
  # a query for retrieving NS and similar records
  ns-query string;
  # a query for retrieving the rest of RRs
  rr-query string;
  # a query for retrieving RRs from reverse delegation zones
  rev-rr-query string;
}

Statements within the sync block configure the zones:

Configuration: zone-conf pat: Defines the pattern for the name of zone configuration file for zones in this synchronization block. If not supplied, the global zone-conf statement will be used instead (see zone-conf).

Configuration: zonefile-pattern pat: Defines the pattern for zone file names. If not supplied, the global zonefile-pattern statement will be used instead (see zonefile-pattern).

Configuration: add-statements text

Append text to each generated zone statement. For example, the following can be used to redefine forwarders and query ACLs for zones in this synchronization block:

add-statements <<EOT
  forwarders { /* empty */ };
  allow-query { local-query-only; };
EOT;

Notice the use of the here-document construct.

The following statements define which zones pertain to this particular synchronization block:

Configuration: soa-query string: A query for retrieving SOA records.

Configuration: ns-query string: A query for retrieving NS and similar records. Use the ‘$zone’ reference for the zone name.

Configuration: rr-query string: A query for retrieving the rest of RRs. Use the ‘$zone’ reference for the zone name.

Configuration: rev-rr-query string: A query for retrieving RRs from reverse delegation zones. Use the ‘$zone’ reference for the zone name.

Here is an example of a working sync directive:

sync external {
  zone-conf "/var/namedb/nssync/zones.external";
  zonefile-pattern "/var/namedb/external/db.${zone}";
  
  soa-query    "select zone, ttl, type, data, resp_person, "
               "serial, refresh, retry, expire, minimum "
               "from dns_soa where type='SOA' "
               "and view='external' order by zone";
               
  ns-query     "select ttl, type, data "
               "from dns_soa where zone='$zone' "
               "and type<>'SOA' and view='external'";
               
  rr-query     "select host, ttl, type, mx_priority, "
               "case when type='TXT' then "
               "concat('\"', data, '\"') "
               "else data end "
               "from dns_records "
               "where zone='$zone' and view='external' "
               "order by 1";
               
  rev-rr-query "select host, ttl, type, mx_priority, "
               "case when type='TXT' then "
               "concat('\"', data, '\"') "
               "else data end "
               "from dns_records "
               "where zone='$zone' and view='external' "
               "order by cast(host as unsigned)";
}

This document was generated on April 24, 2015 using makeinfo.

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NSSYNC

DNS Zone Files Maintenance Utility

4.3 Synchronization Block