[mythtv-users] RFC: Using DNS-SD to bootstrap MythTV

[Paul Bender]

(1) Background:

I maintain a diskless MythTV frontend distribution called MiniMyth 
<http://linpvr.org/minimyth>. Since it is diskless, it has no storage 
for configuration information. Currently, configuration information is 
stored on a TFTP server. However, since everyone using MythTV has a SQL 
database, I would like to move the configuration information into the 
SQL database. In particular, I would like to put in the MythTV database 
(mythcoverg).

However, there is a problem. I need to know the values of DBHostName, 
DBUserName, DBPassword, DBName and DBType in order to find and connect 
to the database. Therefore, this information cannot be stored in the 
database.

I have a proposal to solve this problem on which I would like feedback.

(2) Proposal:

The proposal is to use DNS based service discovery (DNS-SD) 
<http://www.dns-sd.org/> as defined in 
<http://files.dns-sd.org/draft-cheshire-dnsext-dns-sd.txt> to discover 
the information found in the 'mysql.txt' file. The service type 
<http://www.dns-sd.org/ServiceTypes.html> would be 'mythtv-db' and the 
defined TXT keys would be 'txtvers', 'DBUserName', 'DBPassword', 
'DBName', 'DBType', 'WOLsqlReconnectWaitTime', 'WOLsqlConnectRetry' and 
'WOLsqlCommand', and 'WOLsqlMAC'. (Note: in DNS-SD, these key names must 
be treated as case insensitive).

The 'txtvers' key is the  DNS-SD ID suggest version tag. The value will 
be '000'.

The 'WOLsqlMAC' key does not appear in 'mysql.txt'. However, since the 
DNS server may know which WOL commands the MythTV frontends support (in 
fact they may not be the same for all frontends in the network), I 
believe that it is cleaner to provide the MAC address that will be used 
by the WOL command rather than the WOL command itself. However, a 
'WOLLsqlCommand' key is available as well.

If we decide to move forward with this then it should be registered with 
<http://www.dns-sd.org/ServiceTypes.html>.

Comments?