# The configuration database module - cfg_db

## Admin Guide

### Overview

The module implements a database driver for the configuration parameters API. When configuration parameters are being declared (typically when starting) API then driver is notified and has chance to set value (of any parameter) based on value taken from database. It's primarily targeted for interfacing with 3rd party software which is aware of the &kamailio; configuration.

A parameter is uniquely identified by a group_name plus a name, which is used by the driver to check if a value can be found. Because configuration parameters may be spread in many tables, a translation table is used to indicate where to start searching. Multiple look-up tables may be defined for single parameter, tables are searched in the first round by exact match until parameter is found, all tables listed with wildcard (asterisk) in group name are searched in the second round. If a parameter is not found then its value is left unchanged.

Configuration parameters are normally declared in C code and this module additionally supports also declaring custom parameters in extra table. Such parameters may be used typically in script only. All parameters listed in the table are declared in the first step, values are initialized in the second step using the same procedure as C-code parameters.

The module does not reflect changes made in parameters when &kamailio; is running. It just declares variables and assigns values when &kamailio; is starting. That's all.

### Dependencies

A loaded database module.

### Examples

#### Content of tables

    	cfg_transl table:
    	group_name|name|cfg_table|cfg_table_group_name_field|cfg_table_name_field|cfg_table_value_field
    	core|use_dst_blocklist|cfg_dns|||
    	core|dst_blocklist_mem|cfg_dns|||
    	core|dst_blocklist_expire|||
    	my|route_addr|cfg_my|my_group_name|my_name|my_value	; overrides <default> values
    	my|use_rtp_proxy|cfg_my|my_group_name|my_name|my_value
    	*|*||||	; matches all param ids, points to tables defined in row <default>
    	<default>||cfg_var|group_name|name|value  ; default cfg_table* values

    	cfg_custom table:
    	group_name|name|value_type|min_value|max_value|description
    	my|route_addr|S|||Routing address
    	my|use_rtp_proxy|I|0|1|Use RTP proxy

    	cfg_var table:
    	group_name|my_name|value
    	core|debug|4

    	cfg_my table:
    	my_group_name|my_name|my_value
    	my|route_addr|127.0.0.1
    	my|use_rtp_proxy|1

    	cfg_dns table:
    	group_name|name|value
    	dns|use_dst_blocklist|1
    	dns|dst_blocklist_mem|1024
    	dns|dst_blocklist_expire|60