Daniel-Constantin Mierla

Edited by

Daniel-Constantin Mierla

Vicente Hernando

Table of Contents

1. Admin Guide
1. Overview
2. Dependencies
2.1. Kamailio Modules
2.2. External Libraries or Applications
3. Parameters
3.1. server (str)
4. Functions
4.1. redis_cmd(srvname, command, ..., replyid)
4.2. redis_free(replyid)

List of Examples

1.1. Set server parameter
1.2. redis_cmd usage
1.3. redis_free usage

Chapter 1. Admin Guide

1. Overview

This module provides a connector to interact with REDIS NoSQL Database from configuration file. You can read more about REDIS at http://redis.io.

It can connect to many REDIS servers and store the results in different containers.

2. Dependencies

2.1. Kamailio Modules

The following modules must be loaded before this module:

  • none.

2.2. 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/antirez/hiredis .

3. Parameters

3.1. server (str)

Specify the details to connect to REDIS server. It takes a list of attribute=value separated by semicolon, the attributes can be name, unix, addr, port and db. Name is a generic identifier to be used with module functions. unix is the path to the unix domain socket provided by redis server. addr and port are the IP address and the port to connect to REDIS server. unix and (addr, port) are mutually exclusive. If both appear in same server settings unix domain socket is configured. db is the DB number to use (defaults to 0 if not specified).

You can set this parameter many times, in case you want to connect to many REDIS servers, just give different attributes and use the specific server name when querying the REDIS instance.

Default value is NULL.

Example 1.1. Set server parameter

modparam("ndb_redis", "server", "name=srvN;addr=;port=6379;db=1")
modparam("ndb_redis", "server", "name=srvX;addr=;port=6379;db=4")

# Unix domain socket
modparam("ndb_redis", "server", "name=srvY;unix=/tmp/redis.sock;db=3")

4. Functions

4.1.  redis_cmd(srvname, command, ..., replyid)

Send a command to REDIS server identified by srvname. The reply will be stored in a local container identified by replyid. All the parameters can be strings with pseudo-variables that are evaluated at runtime.

Minimum required arguments are srvname, command and replyid. Command argument can be separated into several ones using %s token. (See examples) Total number of arguments cannot exceed six.

The reply can be accessed via pseudo-variable $redis(key). The key can be: type - type of the reply (as in hiredis.h); value - the value returned by REDIS server; info - in case of error from REDIS, it will contain an info message.

If reply type is an array (as in hiredis.h), there are other keys available:

  • size - returns number of elements in the array.

  • type[n] - returns the type of the nth element in the array. type - returns array type.

  • value[n] - returns value of the nth element. value - returns null for an array. You need to get each element by index.

Example 1.2. redis_cmd usage

if(redis_cmd("srvN", "INCR cnt", "r")) {
    # success - the incremented value is in $redis(r=>value)
    xlog("===== $redis(r=>type) * $redis(r=>value)\n");

# set a value
redis_cmd("srvN", "SET foo bar", "r");

redis_cmd("srvN", "SET ruri $ru", "r");

# get a value
redis_cmd("srvN", "GET foo", "r");

# same command separated into two arguments:
redis_cmd("srvN", "GET %s", "foo", "r");

# if we have a key with spaces within it:
redis_cmd("srvN", "GET %s", "foo bar", "r");

# several values substitution:
redis_cmd("srvN", "HMGET %s %s %s", "key1", "field1", "field2", "r");

# array example
if(redis_cmd("srvN", "HMGET foo_key field1 field3", "r")) {
    xlog("array size: $redis(r=>size)\n");
    xlog("first values: $redis(r=>value[0]) , $redis(r=>value[1])\n");

4.2.  redis_free(replyid)

Frees data in a previous reply from memory. After this function call, accessing to a freed replyid returns null value.

It is not necessary to free a reply to use it again in a new redis_cmd function. When ndb_redis module closes, all pending replies are freed automatically.

Example 1.3. redis_free usage

After a redis command call:
	redis_cmd("srvN", "INCR cnt", "r");

free reply data: