Chapter 4. Configure database connectivity

This chapter shows you how to configure the Generic MySQL backend, which we like a lot. But feel free to use any of the myriad other backends. This backend is called 'gmysql', and needs to be configured in pdns.conf. Add the following lines, adjusted for your local setup:

	launch=gmysql
	gmysql-host=127.0.0.1
	gmysql-user=root
	gmysql-dbname=pdnstest
      
Remove any earlier launch statements. Also remove the bind-example-zones statement as the bind module is no longer launched.

Warning

Make sure that you can actually resolve the hostname of your database without accessing the database! It is advised to supply an IP address here to prevent chicken/egg problems!

Warning

Be very very sure that you configure the *g*mysql backend and not the mysql backend. See Section A.5. If you use the 'mysql' backend things will only appear to work.

Now start PDNS using the monitor command:

	# /etc/init.d/pdns monitor
	(...)
	15:31:30 About to create 3 backend threads
	15:31:30 [gMySQLbackend] Failed to connect to database: Error: Unknown database 'pdnstest'
	15:31:30 [gMySQLbackend] Failed to connect to database: Error: Unknown database 'pdnstest'
	15:31:30 [gMySQLbackend] Failed to connect to database: Error: Unknown database 'pdnstest'
      
This is as to be expected - we did not yet add anything to MySQL for PDNS to read from. At this point you may also see other errors which indicate that PDNS either could not find your MySQL server or was unable to connect to it. Fix these before proceeding.

General MySQL knowledge is assumed in this chapter, please do not interpret these commands as DBA advice!

4.1. Configuring MySQL

Connect to MySQL as a user with sufficient privileges and issue the following commands:

create table domains (
 id		 INT auto_increment,
 name		 VARCHAR(255) NOT NULL,
 master		 VARCHAR(128) DEFAULT NULL,
 last_check	 INT DEFAULT NULL,
 type		 VARCHAR(6) NOT NULL,
 notified_serial INT DEFAULT NULL, 
 account         VARCHAR(40) DEFAULT NULL,
 primary key (id)
)type=InnoDB;

CREATE UNIQUE INDEX name_index ON domains(name);

CREATE TABLE records (
  id              INT auto_increment,
  domain_id       INT DEFAULT NULL,
  name            VARCHAR(255) DEFAULT NULL,
  type            VARCHAR(6) DEFAULT NULL,
  content         VARCHAR(255) DEFAULT NULL,
  ttl             INT DEFAULT NULL,
  prio            INT DEFAULT NULL,
  change_date     INT DEFAULT NULL,
  primary key(id)
)type=InnoDB;

CREATE INDEX rec_name_index ON records(name);
CREATE INDEX nametype_index ON records(name,type);
CREATE INDEX domain_id ON records(domain_id);

create table supermasters (
  ip VARCHAR(25) NOT NULL, 
  nameserver VARCHAR(255) NOT NULL, 
  account VARCHAR(40) DEFAULT NULL
);

GRANT SELECT ON supermasters TO pdns;
GRANT ALL ON domains TO pdns;
GRANT ALL ON records TO pdns;
	
Now we have a database and an empty table. PDNS should now be able to launch in monitor mode and display no errors:
	  # /etc/init.d/pdns monitor
	  (...)
	  15:31:30 PowerDNS 1.99.0 (Mar 12 2002, 15:00:28) starting up
	  15:31:30 About to create 3 backend threads
	  15:39:55 [gMySQLbackend] MySQL connection succeeded
	  15:39:55 [gMySQLbackend] MySQL connection succeeded
	  15:39:55 [gMySQLbackend] MySQL connection succeeded
	
A sample query sent to the database should now return quickly without data:
	  $ host www.test.com 127.0.0.1
	  www.test.com A record currently not present at localhost
	
And indeed, the control console now shows:
	  Mar 12 15:41:12 We're not authoritative for 'www.test.com', sending unauth normal response
	
Now we need to add some records to our database:
	  # mysql pdnstest
	  mysql> INSERT INTO domains (name, type) values ('test.com', 'NATIVE');
	  INSERT INTO records (domain_id, name, content, type,ttl,prio) 
	  VALUES (1,'test.com','localhost ahu@ds9a.nl 1','SOA',86400,NULL);
	  INSERT INTO records (domain_id, name, content, type,ttl,prio)
	  VALUES (1,'test.com','dns-us1.powerdns.net','NS',86400,NULL);
	  INSERT INTO records (domain_id, name, content, type,ttl,prio)
	  VALUES (1,'test.com','dns-eu1.powerdns.net','NS',86400,NULL);
	  INSERT INTO records (domain_id, name, content, type,ttl,prio)
	  VALUES (1,'www.test.com','199.198.197.196','A',120,NULL);
	  INSERT INTO records (domain_id, name, content, type,ttl,prio)
	  VALUES (1,'mail.test.com','195.194.193.192','A',120,NULL);
	  INSERT INTO records (domain_id, name, content, type,ttl,prio)
	  VALUES (1,'localhost.test.com','127.0.0.1','A',120,NULL);
	  INSERT INTO records (domain_id, name, content, type,ttl,prio)
	  VALUES (1,'test.com','mail.test.com','MX',120,25);
	
If we now requery our database, www.test.com should be present:
	  $ host www.test.com 127.0.0.1
	  www.test.com        	A	199.198.197.196
	  
	  $ host -v -t mx test.com 127.0.0.1
	  Address: 127.0.0.1
	  Aliases: localhost

	  Query about test.com for record types MX
	  Trying test.com ...
	  Query done, 1 answer, authoritative status: no error
	  test.com            	120	IN	MX	25 mail.test.com
	  Additional information:
	  mail.test.com       	120	IN	A	195.194.193.192
	
To confirm what happened, issue the command SHOW * to the control console:
	  % show *
	  corrupt-packets=0,latency=0,packetcache-hit=2,packetcache-miss=5,packetcache-size=0,
	  qsize-a=0,qsize-q=0,servfail-packets=0,tcp-answers=0,tcp-queries=0,
	  timedout-packets=0,udp-answers=7,udp-queries=7,
	  % 
	
The actual numbers will vary somewhat. Now enter QUIT and start PDNS as a regular daemon, and check launch status:
	  # /etc/init.d/pdns start 
	  pdns: started
	  # /etc/init.d/pdns status
	  pdns: 8239: Child running
	  # /etc/init.d/pdns dump  
	  pdns: corrupt-packets=0,latency=0,packetcache-hit=0,packetcache-miss=0,
	  packetcache-size=0,qsize-a=0,qsize-q=0,servfail-packets=0,tcp-answers=0,
	  tcp-queries=0,timedout-packets=0,udp-answers=0,udp-queries=0,
	
You now have a working database driven nameserver! To convert other zones already present, use the zone2sql described in Appendix A.

4.1.1. Common problems

Most problems involve PDNS not being able to connect to the database.

Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)

Your MySQL installation is probably defaulting to another location for its socket. Can be resolved by figuring out this location (often /var/run/mysqld.sock), and specifying it in the configuration file with the gmysql-socket parameter.

Another solution is to not connect to the socket, but to 127.0.0.1, which can be achieved by specifying gmysql-host=127.0.0.1.

Host 'x.y.z.w' is not allowed to connect to this MySQL server

These errors are generic MySQL errors. Solve them by trying to connect to your MySQL database with the MySQL console utility mysql with the parameters specified to PDNS. Consult the MySQL documentation.