DB_REDIS Module

Andreas Granig

   <agranig@sipwise.com>

Edited by

Andreas Granig

   <agranig@sipwise.com>

Edited by

Alex Balashov

   <abalashov@evaristesys.com>

   Copyright © 2018 sipwise.com
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Limitations
        3. Dependencies

              3.1. Kamailio Modules
              3.2. External Libraries or Applications

        4. Parameters

              4.1. schema_path (string)
              4.2. keys (string)
              4.3. verbosity (int)

        5. Usage
        6. Module Specific Considerations

              6.1. usrloc

   List of Examples

   1.1. Setting schema_path module parameter
   1.2. Setting keys module parameter
   1.3. Setting verbosity module parameter
   1.4. Usage
   1.5. Usage

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Limitations
   3. Dependencies

        3.1. Kamailio Modules
        3.2. External Libraries or Applications

   4. Parameters

        4.1. schema_path (string)
        4.2. keys (string)
        4.3. verbosity (int)

   5. Usage
   6. Module Specific Considerations

        6.1. usrloc

1. Overview

   This module provides a DB APIv1 connector for the Redis server
   (https://www.redis.io).

   It can be used as a replacement for other database modules such as
   db_mysql and db_postgres. Not all the specs of DB APIv1 are
   implemented, thus the usage of this module might be restricted to
   specific modules. Also, for proper performance, this module needs
   particular configuration tailored to the modules that make use of it.

   Since Redis does not provide a schema by itself, db_redis ships with
   schema files. The path to these has to be defined using the module
   parameter "schema_path". The schema definition is defined in one file
   per table, such that the file name corresponds to the table name, and
   each file is composed of a comma-separated list of column definitions
   in the format <column-name>/<type>[,<column-name>/<type> ...] in one
   line, followed by a line holding the table version.

   Example definition for the "location" table (from the usrloc module):
username/string,domain/string,contact/string,received/string,path/string,expires
/timestamp,q/double,callid/string,cseq/int,last_modified/timestamp,flags/int,cfl
ags/int,user_agent/string,socket/string,methods/int,ruid/string,reg_id/int,insta
nce/string,server_id/int,connection_id/int,keepalive/int,partition/int
8

   Because Redis is a key-value store, it requires unique keys. This means
   that tables and rows from a relational SQL database, e.g. from MySQL,
   can not be ported one a 1:1 basis to Redis.

   For instance, usrloc relies on a key of "username@domain", but in order
   to store multiple contacts per AoR, it cannot be constrained to
   uniqueness. To work around this, db_redis supports mapping sets in such
   a way as to, in the case of the usrloc module, have a set with a key of
   "username@domain" and its entries being unique keys per contact based
   on the ruid of a contact. Thus, one contact in usrloc consists of a
   unique key "location:entry::example-ruid-1" being a hash with the
   columns like username, domain, contact, path etc. In addition, this
   unique key is stored in a set
   "location:usrdom::exampleuser:exampledomain.org". When usrloc does a
   lookup based on "username@domain", db_redis figures out via the
   keys/values the query constructed by usrloc to look for the final entry
   key in the mapping set first. It then query the actual entries from
   there, avoiding full table scans. For usrloc, the same holds true for
   expired contacts, requiring a different kind of mapping. There is a
   certain balance of read performance vs. write performance to consider,
   because inserts and deletes also have to maintain the mappings, though
   this yields much faster selects. The mappings can be freely defined, so
   even though other kamailio modules don't require a specific mapping to
   be in place for proper performance, mappings could be defined for
   external applications to read faster (for instance letting the acc
   module also write mappings besides the actual records for billing
   systems to correlate start and stop records faster).

   The key is always prefixed with 'tablename:entry::'. For example the
   record in 'subscriber' table for user 'alice@sip.com' has the key:
   'subscriber:entry::alice:sip.com'. If all the records are just loaded
   at startup (or all reloaded at runtime), the key can just be made
   unique using whatever values added after 'tablename:entry::' prefix.
   For example, keys for 'address' table records can be:
   'address:entry::1', address:entry::2', address:entry::3', ... No 'keys'
   modparam of 'db_redis' for 'address' table needs to be defined.

   Important Note: at this moment the module requires at least one 'keys'
   parameter, but it does not need to be related to the table loaded from
   Redis server -- for example, if used only for permissions module with
   'address' table, then the 'keys' parameter can be specified for
   'version' table.

   The mappings can be freely defined in the "keys" module parameter,
   which is composed of a semi-colon separated list of definitions in the
   format
   <table-name>=<entry>:<column-name>[&<map-name>:<column-name>,<column-na
   me>...]. Each table must at least have an "entry" key for db_redis to
   be able to store data.

   Example:
location=entry:ruid&usrdom:username,domain&timer:partition,keepalive;acc=entry:c
allid,time_hires&cid:callid

   For readability purposes, definitions of keys per table can span
   multiple Kamailio config lines by providing multiple "keys" modparams.

2. Limitations

     * This module has implemented equivalent underlying Redis operations
       for INSERT, UPDATE, DELETE and SELECT. The ORDER BY clause for
       SELECT is not implemented. Raw querying is not implemented inside
       this module; for sending literal commands to the Redis server, use
       ndb_redis.

3. Dependencies

   3.1. Kamailio Modules
   3.2. External Libraries or Applications

3.1. Kamailio Modules

   The following modules must be loaded before this module:
     * none.

3.2. External Libraries or Applications

   The following libraries or applications must be installed before
   running Kamailio with this module loaded:
     * hiredis - available at https://github.com/redis/hiredis

4. Parameters

   4.1. schema_path (string)
   4.2. keys (string)
   4.3. verbosity (int)

4.1. schema_path (string)

   The path to the table schemas.

   Default value: "/usr/share/kamailio/db_redis".

   Example 1.1. Setting schema_path module parameter
...
modparam("db_redis", "schema_path", "/usr/local/share/kamailio/db_redis/kamailio
")
...

4.2. keys (string)

   The entry and mapping keys of tables.

   Default value: "" (empty).

   Example 1.2. Setting keys module parameter
...
modparam("db_redis", "keys", "version=entry:table_name;location=entry:ruid&usrdo
m:username,domain&timer:partition,keepalive")
...

4.3. verbosity (int)

   Control the verbosity of debug messages printed by the module. If set
   to 1, the module prints schema details for all tables on each connect
   operation to Redis server.

   Default value: 1.

   Example 1.3. Setting verbosity module parameter
...
modparam("db_redis", "verbosity", 0)
...

5. Usage

   Load the module and set the "db_url" modparam for specific modules to:
   'redis://[username]@host:port/database'. Username is optional. The
   database portion must be a valid Redis database number.

   Example 1.4. Usage
...
loadmodule "db_redis.so"
...
#!define DBURL_USRLOC "redis://127.0.0.1:6379/5"
#!define DBURL_ACC    "redis://127.0.0.1:6379/6"
#!define DBURL_AUTH   "redis://127.0.0.1:6379/7"
#!define DBURL_PERM   "redis://127.0.0.1:6379/8"
...
modparam("db_redis", "schema_path", "/usr/share/kamailio/db_redis/kamailio")
modparam("db_redis", "keys", "version=entry:table_name")
modparam("db_redis", "keys", "location=entry:ruid&usrdom:username,domain&timer:p
artition,keepalive")
modparam("db_redis", "keys", "acc=entry:callid,time_hires&cid:callid")
modparam("db_redis", "keys", "subscriber=entry:username,domain")
...
modparam("usrloc", "db_url", DBURL_USRLOC)
...
modparam("acc_db", "db_url", DBURL_ACC)
...
modparam("auth_db", "db_url", DBURL_AUTH)
...
modparam("permissions", "db_url", DBURL_PERM)
...

   Samples adding records for address table using 'redis-cli':

   Example 1.5. Usage
...
SELECT 8
HMSET address:entry::1 id 1 grp 1 ip_addr "127.0.0.1" mask 32 port 0
HMSET address:entry::2 id 2 grp 1 ip_addr "127.0.0.2" mask 32 port 0
HMSET address:entry::3 id 3 grp 2 ip_addr "127.0.0.3" mask 32 port 0
HMSET address:entry::4 id 4 grp 2 ip_addr "127.0.0.4" mask 32 port 0 tag "test"
...

   Note that is some cases, the optional values in database tables can be
   omitted. For 'address' table, the 'tag' value may be omitted. To avoid
   any issues, set unused fields to their default values as defined by
   database schema. When definition allows 'NULL', that field can be
   unset.

6. Module Specific Considerations

   6.1. usrloc

6.1. usrloc

   If you set "expires_type" to "1" in order to use BIGINT instead of
   DATETIME, make sure to update your location schema file and change the
   type of "expires" and "last_modified" from "time" to "int".
