CACHEDB_REDIS module

Admin Guide

Overview

This module is an implementation of a cache system designed to work with a Redis server. It uses hiredis client library to connect to either a single Redis server instance, or to a Redis Server inside a Redis Cluster. It uses the Key-Value interface exported from the core.

Advantages

memory costs are no longer on the server
many servers can be used inside a cluster, so the memory is virtually unlimited
the cache is 100% persistent. A restart of OpenSIPS server will not affect the DB. The Redis DB is also persistent so it can also be restarted without loss of information.
redis is an open-source project so it can be used to exchange data with various other applications
By creating a Redis Cluster, multiple OpenSIPS instances can easily share key-value information

Limitations

keys (in key:value pairs) may not contain spaces or control characters

Dependencies

OpenSIPS Modules

The following modules must be loaded before this module:

If a use tls is defined, the tls_mgm module will need to be loaded as well.

External Libraries or Applications

The following libraries or applications must be installed before running OpenSIPS with this module loaded:

hiredis: On the latest Debian based distributions, hiredis can be installed by running ‘apt-get install libhiredis-dev’

Alternatively, if hiredis is not available on your OS repos, hiredis can be downloaded from: https://github.com/antirez/hiredis . Download the archive, extract sources, run make,sudo make install. If TLS connections are enabled via the use tls modparam, hiredis needs to be compiled with TLS support.

Exported Parameters

cachedb_url (string)

The URLs of the server groups that OpenSIPS will connect to in order to use, from script, the cache_store(), cache_fetch(), etc. operations. It may be set more than once. The prefix part of the URL will be the identifier that will be used from the script.

...
# single-instance URLs (Redis Server or Redis Cluster)
modparam("cachedb_redis", "cachedb_url", "redis:group1://localhost:6379/")
modparam("cachedb_redis", "cachedb_url", "redis:cluster1://random_url:8888/")

# multi-instance URL (will perform circular

...
cache_store("redis:group1", "key", "$ru value");
cache_fetch("redis:cluster1", "key", $avp(10));
cache_remove("redis:cluster1", "key");
...

connect_timeout (integer)

This parameter specifies how many milliseconds OpenSIPS should wait for connecting to a Redis node.

Default value is “5000 ms”.

...
# wait 1 seconds for Redis to connect
modparam("cachedb_redis", "connect_timeout",1000)
...

query_timeout (integer)

This parameter specifies how many milliseconds OpenSIPS should wait for a query response from a Redis node.

Default value is “5000 ms”.

...
# wait 1 seconds for Redis queries
modparam("cachedb_redis", "query_timeout",1000)
...

shutdown_on_error (integer)

By setting this parameter to 1, OpenSIPS will abort startup if the initial connection to Redis is not possible. Runtime reconnect behavior is unaffected by this parameter, and is always enabled.

Default value is “0” (disabled).

...
# abort OpenSIPS startup if Redis is down
modparam("cachedb_redis", "shutdown_on_error", 1)
...

use_tls (integer)

Setting this parameter will allow you to use TLS for Redis connections. In order to enable TLS for a specific connection, you can use the “tls_domain=dom_name” URL parameter in the cachedb_url of this module (or other modules that use the CacheDB interface). This should be placed at the end of the URL after the ’?’ character.

When using this parameter, you must also ensure that tls_mgm is loaded and properly configured. Refer to the the module for additional info regarding TLS client domains.

Note that TLS is supported by Redis starting with version 6.0. Also, it is an optional feature enabled at compile time and might not be included in the standard Redis packages available for your OS.

Default value is 0 (not enabled)

...
modparam("tls_mgm", "client_domain", "redis")
modparam("tls_mgm", "certificate", "[redis]/etc/pki/tls/certs/redis.pem")
modparam("tls_mgm", "private_key", "[redis]/etc/pki/tls/private/redis.key")
modparam("tls_mgm", "ca_list",     "[redis]/etc/pki/tls/certs/ca.pem")
...
modparam("cachedb_redis", "use_tls", 1)
modparam("cachedb_redis", "cachedb_url","redis://localhost:6379/?tls_domain=redis")
...

Exported Functions

The module does not export functions to be used in configuration script.

Raw Query Syntax

The cachedb_redis module allows to run RAW queries, thus taking full advantage of the capabilities of the back-end.

The query syntax is the typical REDIS one.

Here are a couple examples of running some Redis queries :

...
  $var(my_hash) = "my_hash_name";
  $var(my_key) = "my_key_name";
  $var(my_value) = "my_key_value";
  cache_raw_query("redis","HSET $var(my_hash) $var(my_key) $var(my_value)");
  cache_raw_query("redis","HGET $var(my_hash) $var(my_key)","$avp(result)");
  xlog("We have fetched $avp(result) \n");
...
  $var(my_hash) = "my_hash_name";
  $var(my_key1) = "my_key1_name";
  $var(my_key2) = "my_key2_name";
  $var(my_value1) = "my_key1_value";
  $var(my_value2) = "my_key2_value";
  cache_raw_query("redis","HSET $var(my_hash) $var(my_key1) $var(my_value1)");
  cache_raw_query("redis","HSET $var(my_hash) $var(my_key2) $var(my_value2)");
  cache_raw_query("redis","HGETALL $var(my_hash)","$avp(result)");

  $var(it) = 0;
  while ($(avp(result_final)[$var(it)]) != NULL) {
    xlog("Multiple key reply: - we have fetched $(avp(result_final)[$var(it)]) \n");
    $var(it) = $var(it) + 1;
  }
...

Frequently Asked Questions

Q: My OpenSIPS is occasionally crashing in libhiredis, what to do?

Make sure you’ve upgraded the Redis “libhiredis” client library to at least version 0.14.1. There was at least one significant vulnerability reported in library versions prior to that one (CVE-2020-7105), so upgrading to latest stable may very well fix the crash!

Contributors

By Commit Statistics

Top contributors by DevScore⁽¹⁾, authored commits⁽²⁾ and lines added/removed⁽³⁾

#	Name	DevScore	Commits	Lines++	Lines—
1.	Vlad Paiu (@vladpaiu)	33	19	1451	55
2.	Liviu Chircu (@liviuchircu)	31	19	596	315
3.	Razvan Crainea (@razvancrainea)	17	14	155	60
4.	Vlad Patrascu (@rvlad-patrascu)	13	6	603	46
5.	Stefan Darius (@dariusstefan)	8	4	299	43
6.	Bogdan-Andrei Iancu (@bogdan-iancu)	7	5	10	8
7.	Maksym Sobolyev (@sobomax)	6	4	7	7
8.	jalung	5	1	168	85
9.	Dan Pascu (@danpascu)	3	1	15	15
10.	Kristian Høgh	3	1	13	1

All remaining contributors: Ezequiel Lovelle (@lovelle), John Burke (@john08burke), tcresson, zhengsh, Peter Lemenkov (@lemenkov), Julián Moreno Patiño, Jarrod Baumann (@jarrodb).

(1) DevScore = author_commits + author_lines_added / (project_lines_added / project_commits) + author_lines_deleted / (project_lines_deleted / project_commits)

(2) including any documentation-related commits, excluding merge commits

(3) ignoring whitespace edits, renamed files and auto-generated files

By Commit Activity

#	Name	Commit Activity
1.	Stefan Darius (@dariusstefan)	Jun 2026 - Jul 2026
2.	Razvan Crainea (@razvancrainea)	Feb 2012 - Jun 2026
3.	Vlad Paiu (@vladpaiu)	Oct 2011 - Nov 2024
4.	tcresson	Oct 2023 - Oct 2023
5.	Liviu Chircu (@liviuchircu)	Mar 2014 - Oct 2023
6.	zhengsh	Aug 2023 - Aug 2023
7.	Maksym Sobolyev (@sobomax)	Feb 2023 - Feb 2023
8.	John Burke (@john08burke)	Apr 2022 - Apr 2022
9.	Vlad Patrascu (@rvlad-patrascu)	May 2017 - Jan 2022
10.	Bogdan-Andrei Iancu (@bogdan-iancu)	Oct 2014 - Mar 2020

All remaining contributors: Dan Pascu (@danpascu), Peter Lemenkov (@lemenkov), Kristian Høgh, Julián Moreno Patiño, Jarrod Baumann (@jarrodb), jalung, Ezequiel Lovelle (@lovelle).

(1) including any documentation-related commits, excluding merge commits

Documentation

Contributors

Last edited by: Razvan Crainea (@razvancrainea), Liviu Chircu (@liviuchircu), Vlad Patrascu (@rvlad-patrascu), Peter Lemenkov (@lemenkov), Julián Moreno Patiño, Vlad Paiu (@vladpaiu).

License

All documentation files (i.e. .md extension) are licensed under the Creative Common License 4.0