cachedb_redis Module
     __________________________________________________________

   Table of Contents

   1. Admin Guide

        1.1. Overview
        1.2. Advantages
        1.3. Redis Stack Support
        1.4. Redis Cluster Support (Topology)

              1.4.1. Topology Discovery
              1.4.2. Automatic Topology Refresh
              1.4.3. MOVED Redirection
              1.4.4. Hash Tags

        1.5. Limitations
        1.6. Dependencies

              1.6.1. OpenSIPS Modules
              1.6.2. External Libraries or Applications

        1.7. Exported Parameters

              1.7.1. cachedb_url (string)
              1.7.2. connect_timeout (integer)
              1.7.3. query_timeout (integer)
              1.7.4. shutdown_on_error (integer)
              1.7.5. lazy_connect (integer)
              1.7.6. use_tls (integer)
              1.7.7. ftsearch_index_name (string)
              1.7.8. ftsearch_json_prefix (string)
              1.7.9. ftsearch_max_results (integer)
              1.7.10. redis_keepalive (integer)
              1.7.11. ftsearch_json_mset_expire (integer)

        1.8. Exported Functions
        1.9. Exported MI Functions

              1.9.1. redis_cluster_info
              1.9.2. redis_cluster_refresh
              1.9.3. redis_ping_nodes

        1.10. Exported Statistics

              1.10.1. redis_queries
              1.10.2. redis_queries_failed
              1.10.3. redis_moved
              1.10.4. redis_topology_refreshes

        1.11. Raw Query Syntax

   2. Contributors

        2.1. By Commit Statistics
        2.2. By Commit Activity

   3. Documentation

        3.1. Contributors

   4. Frequently Asked Questions

   List of Tables

   1.1. URL Authentication Formats
   2.1. Top contributors by DevScore^(1), authored commits^(2) and
          lines added/removed^(3)

   2.2. Most recently active contributors^(1) to this module

   List of Examples

   1.1. Set cachedb_url parameter
   1.2. Use Redis servers
   1.3. Set connect_timeout parameter
   1.4. Set query_timeout parameter
   1.5. Set the shutdown_on_error parameter
   1.6. Set the lazy_connect parameter
   1.7. Set the use_tls parameter
   1.8. Set the ftsearch_index_name parameter
   1.9. Set the ftsearch_json_prefix parameter
   1.10. Set the ftsearch_max_results parameter
   1.11. Set redis_keepalive parameter
   1.12. Set the ftsearch_json_mset_expire parameter
   1.13. Redis Raw Query Examples

Chapter 1. Admin Guide

1.1. 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.

1.2. 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

1.3. Redis Stack Support

   Starting with OpenSIPS 3.6, the cachedb_redis module implements
   the column-oriented cacheDB API functions. This makes it a
   suitable cacheDB storage in scenarios such as user location
   federation and full-sharing, which require this API to be
   available.

   The implementation makes use of RedisJSON and RediSearch --
   these relatively new features are available in Redis Stack
   Server, instead of the usual Redis Server (Redis OSS project).
   More documentation is available on the Redis website.

   OpenSIPS will auto-detect availability of the RedisJSON support
   when necessary and log the appropriate messages.

1.4. Redis Cluster Support (Topology)

   When connecting to a Redis Cluster, the module automatically
   detects cluster mode and manages the full slot-to-node topology
   at runtime. No extra configuration is needed beyond the
   standard cachedb_url parameter.

1.4.1. Topology Discovery

   At startup, the module probes the Redis server using the
   CLUSTER SHARDS command (available in Redis 7.0+). If the server
   does not support this command, it falls back to CLUSTER SLOTS
   (available in Redis 3.0+). If neither command succeeds, the
   connection is treated as a single-instance (non-cluster)
   connection.

   The discovered topology is stored internally in an O(1) slot
   lookup table (16384 slots), mapping each slot directly to its
   owning master node.

1.4.2. Automatic Topology Refresh

   The module automatically refreshes the cluster topology at
   runtime when any of the following events occur:
     * A MOVED redirection is received from a cluster node
       (indicating a permanent slot migration).
     * A connection failure (NULL reply) occurs and the node
       cannot be reconnected.
     * A query targets a slot with no known owner, suggesting the
       topology is stale.
     * An operator triggers a manual refresh via the
       redis_cluster_refresh MI command.

   Automatic refreshes are rate-limited to at most once per second
   to avoid excessive load on the cluster. The MI-triggered
   refresh bypasses this rate limit.

1.4.3. MOVED Redirection

   The module transparently handles Redis Cluster MOVED
   redirections:
     * MOVED — indicates a permanent slot migration. The module
       updates its slot map, redirects the query to the new node,
       and triggers a topology refresh so all future queries go
       directly to the correct node.

   If a redirection points to a node that is not yet known, the
   module dynamically creates a new node entry, establishes a
   connection, and retries the query.

1.4.4. Hash Tags

   The module supports Redis Cluster hash tags, which allow
   related keys to be co-located on the same cluster node. If a
   key contains a {...} substring, only the content between the
   first { and the next } is used for hash slot calculation. For
   example, the keys {user1000}.profile and {user1000}.settings
   will always land on the same node, enabling multi-key
   operations.

   If the braces are empty ({}) or there is no closing brace, the
   entire key is hashed as usual.

1.5. Limitations

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

1.6. Dependencies

1.6.1. OpenSIPS Modules

   The following modules must be loaded before this module:
     * If a use_tls is defined, the tls_mgm and tls_openssl
       modules will need to be loaded as well.

1.6.2. 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.

1.7. Exported Parameters

1.7.1. 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.

   Example 1.1. Set cachedb_url parameter
...
# 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:88
88/")

# multi-instance URL (will perform circular failover on each query)
modparam("cachedb_redis", "cachedb_url",
        "redis:ha://localhost,host_a:6380,host_b:6381,host_c/")
...

   Example 1.2. Use Redis servers
...
cache_store("redis:group1", "key", "$ru value");
cache_fetch("redis:cluster1", "key", $avp(10));
cache_remove("redis:cluster1", "key");
...

1.7.1.1. Authentication

   The module supports three authentication modes based on the URL
   format:

   Table 1.1. URL Authentication Formats
   URL Format AUTH Command Use Case
   redis:group://:password@host:port/ AUTH password Classic Redis
   (< 6.0) with requirepass
   redis:group://username:password@host:port/ AUTH username
   password Redis 6+ ACL with per-user credentials
   redis:group://host:port/ (none) Non-authenticated Redis

   Important: For classic password-only authentication, the URL
   must include a colon before the password (:password@host).
   Writing password@host without the colon will place the
   credential in the username field of the URL parser, and
   authentication will be skipped.

   When connecting to a Redis Cluster with authentication, all
   discovered cluster nodes use the same credentials from the URL.

1.7.1.2. Unix Socket

   Starting with this version, the module supports connecting to a
   local Redis instance via a Unix domain socket instead of TCP.
   This can provide lower latency and avoid network overhead for
   co-located Redis instances.

   To use a Unix socket, add a socket= parameter to the URL query
   string:
# basic Unix socket (no auth)
modparam("cachedb_redis", "cachedb_url",
    "redis:local://localhost/?socket=/var/run/redis/redis.sock")

# Unix socket with password auth
modparam("cachedb_redis", "cachedb_url",
    "redis:local://:password@localhost/?socket=/var/run/redis/redis.sock
")

# Unix socket with ACL auth (Redis 6+) and database selection
modparam("cachedb_redis", "cachedb_url",
    "redis:local://user:pass@localhost/2?socket=/var/run/redis/redis.soc
k")

   Constraints:
     * Unix socket connections are always treated as
       single-instance mode (no Redis Cluster support over Unix
       sockets).
     * Unix socket cannot be combined with multiple hosts
       (failover). Specifying both will cause a startup error.
     * TLS is not applicable to Unix socket connections and will
       be ignored with a warning if use_tls is enabled.
     * TCP keepalive is not applicable to Unix sockets and is
       automatically skipped.

   The redis_cluster_info MI command will display Unix socket
   connections with transport=unix and the socket path. The
   redis_ping_nodes command works normally with Unix socket
   connections.

1.7.2. connect_timeout (integer)

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

   Default value is “5000 ms”.

   Example 1.3. Set connect_timeout parameter
...
# wait 1 second for Redis to connect
modparam("cachedb_redis", "connect_timeout",1000)
...

1.7.3. 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”.

   Example 1.4. Set query_timeout parameter
...
# wait 1 second for Redis queries
modparam("cachedb_redis", "query_timeout",1000)
...

1.7.4. 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).

   Example 1.5. Set the shutdown_on_error parameter
...
# abort OpenSIPS startup if Redis is down
modparam("cachedb_redis", "shutdown_on_error", 1)
...

1.7.5. lazy_connect (integer)

   By setting this parameter to 1, OpenSIPS will defer
   establishing Redis connections until the first cache operation
   is actually performed by each worker process. This prevents
   idle worker processes (those that never use Redis) from holding
   open sockets, which avoids sockets getting stuck in CLOSE_WAIT
   state when Redis is restarted.

   When this parameter is enabled, the shutdown_on_error parameter
   has no effect, since no connection is attempted at startup
   time.

   Default value is “0” (disabled — connect at startup, preserving
   existing behavior).

   Example 1.6. Set the lazy_connect parameter
...
# defer Redis connections until first use
modparam("cachedb_redis", "lazy_connect", 1)
...

1.7.6. 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 tls_mgm 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)

   Example 1.7. Set the use_tls parameter
...
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.ke
y")
modparam("tls_mgm", "ca_list",     "[redis]/etc/pki/tls/certs/ca.pem")
...
modparam("cachedb_redis", "use_tls", 1)
modparam("cachedb_redis", "cachedb_url","redis:tls_group://localhost:637
9/?tls_domain=redis")
...

1.7.7. ftsearch_index_name (string)

   Only relevant with RedisJSON and RediSearch server-side
   support.

   A global index name to be used for all internal JSON full-text
   search operations. Future extensions may add, e.g., a
   connection-level index name setting.

   Default value is "idx:usrloc".

   Example 1.8. Set the ftsearch_index_name parameter

modparam("cachedb_redis", "ftsearch_index_name", "ix::usrloc")


1.7.8. ftsearch_json_prefix (string)

   Only relevant with RedisJSON and RediSearch server-side
   support.

   A key naming prefix for all internally-created Redis JSON
   objects (e.g. created with JSON.SET or JSON.MSET).

   Default value is "usrloc:".

   Example 1.9. Set the ftsearch_json_prefix parameter

modparam("cachedb_redis", "ftsearch_json_prefix", "userlocation:")


1.7.9. ftsearch_max_results (integer)

   Only relevant with RedisJSON and RediSearch server-side
   support.

   The maximum number of results returned by each
   internally-triggered FT.SEARCH JSON lookup query.

   Default value is 10000 max results.

   Example 1.10. Set the ftsearch_max_results parameter

modparam("cachedb_redis", "ftsearch_max_results", 100)


1.7.10. redis_keepalive (integer)

   TCP keepalive interval in seconds for Redis connections. When
   set to a positive value, the kernel sends TCP probes on idle
   connections to detect dead peers (e.g. due to NAT/firewall idle
   timeout or network partition). This allows the next query to
   fail immediately instead of waiting for the full query timeout,
   enabling faster recovery via the existing retry loop.

   Set to 0 to disable TCP keepalive. Recommended to keep enabled
   for production deployments to prevent silent connection death.

   Default value is “10” (seconds).

   Example 1.11. Set redis_keepalive parameter
...
# set TCP keepalive interval to 15 seconds
modparam("cachedb_redis", "redis_keepalive", 15)

# disable TCP keepalive
modparam("cachedb_redis", "redis_keepalive", 0)
...

1.7.11. ftsearch_json_mset_expire (integer)

   Only relevant with RedisJSON and RediSearch server-side
   support.

   A Redis EXPIRE timer to set/refresh on the JSON key after each
   JSON.MSET operation (create the JSON or add/remove subkeys), in
   seconds. A value of 0 disables the EXPIRE queries completely.

   Default value is 3600 seconds.

   Example 1.12. Set the ftsearch_json_mset_expire parameter

modparam("cachedb_redis", "ftsearch_json_mset_expire", 7200)


1.8. Exported Functions

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

1.9. Exported MI Functions

1.9.1.  redis_cluster_info

   Displays detailed information about all Redis connections
   managed by the module, including cluster topology, per-node
   connection status, slot assignments, and per-node query
   counters.

   Parameters:
     * group (optional) - if specified, only connections belonging
       to this group will be listed (e.g. "local" from a
       "redis:local://..." URL). If omitted, all Redis connections
       are listed.

   The response is a JSON array of connection objects. Each
   connection object includes:
     * group - the connection group name
     * url - the original cachedb_url
     * mode - "cluster" or "single"
     * cluster_command (cluster mode only) - "SHARDS" or "SLOTS",
       depending on which Redis command is used for topology
       discovery
     * topology_refreshes - number of topology refreshes performed
       on this connection
     * last_topology_refresh - UNIX timestamp of the last topology
       refresh
     * nodes - array of cluster node objects, each containing: ip,
       port, status ("connected"/"disconnected"), slots_assigned
       (cluster mode only), queries, errors, moved, last_activity
       (seconds since last successful query, -1 if never queried)
     * total_slots_mapped (cluster mode only) - total number of
       slots with an assigned node (should be 16384 for a healthy
       cluster)

   MI FIFO Command Format:
## list all Redis connections
opensips-cli -x mi redis_cluster_info

## list only the "local" group
opensips-cli -x mi redis_cluster_info group=local

1.9.2.  redis_cluster_refresh

   Forces an immediate topology refresh on Redis Cluster
   connections. This bypasses the normal once-per-second rate
   limit and queries the cluster for its current slot-to-node
   mapping. Useful after manual cluster rebalancing or node
   additions/removals.

   For non-cluster (single instance) connections, the command
   returns a "skipped (not cluster mode)" status.

   Parameters:
     * group (optional) - if specified, only the connection
       belonging to this group will be refreshed. If omitted, all
       cluster connections are refreshed.

   The response is a JSON array of objects, one per connection,
   each containing group and status ("ok", "error", or "skipped
   (not cluster mode)").

   MI FIFO Command Format:
## refresh all cluster connections
opensips-cli -x mi redis_cluster_refresh

## refresh only the "local" group
opensips-cli -x mi redis_cluster_refresh group=local

1.9.3.  redis_ping_nodes

   Sends a PING command to each Redis node and reports per-node
   reachability status with round-trip latency. Useful for
   on-demand health checks without waiting for the next query.

   Parameters:
     * group (optional) - if specified, only nodes belonging to
       this group will be pinged. If omitted, all Redis
       connections are pinged.

   The response is a JSON array of connection objects. Each
   connection object includes:
     * group - the connection group name
     * nodes - array of node objects, each containing: ip, port,
       status ("reachable", "unreachable", or "disconnected"),
       latency_us (round-trip time in microseconds, -1 if not
       reachable)

   MI FIFO Command Format:
## ping all Redis nodes
opensips-cli -x mi redis_ping_nodes

## ping only the "local" group
opensips-cli -x mi redis_ping_nodes group=local

1.10. Exported Statistics

1.10.1. redis_queries

   Total number of successful Redis queries executed across all
   connections and processes.

1.10.2. redis_queries_failed

   Total number of failed Redis queries (NULL replies from hiredis
   or Redis error responses other than MOVED).

1.10.3. redis_moved

   Total number of MOVED redirections received from Redis Cluster
   nodes. A MOVED response indicates a permanent slot migration -
   the module updates its slot map and retries the query on the
   correct node.

1.10.4. redis_topology_refreshes

   Total number of cluster topology refreshes performed (via
   CLUSTER SHARDS or CLUSTER SLOTS). This counter increments both
   for automatic refreshes (triggered by MOVED responses or
   unreachable nodes) and manual refreshes (triggered via the
   redis_cluster_refresh MI command).

1.11. 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 :

   Example 1.13. Redis Raw Query Examples
...
        $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(m
y_value1)");
        cache_raw_query("redis","HSET $var(my_hash) $var(my_key2) $var(m
y_value2)");
        cache_raw_query("redis","HGETALL $var(my_hash)","$avp(result)");

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

Chapter 2. Contributors

2.1. By Commit Statistics

   Table 2.1. Top contributors by DevScore^(1), authored
   commits^(2) and lines added/removed^(3)
     Name DevScore Commits Lines ++ Lines --
   1. Debian 61 3 6168 356
   2. Liviu Chircu (@liviuchircu) 43 23 1720 288
   3. Vlad Paiu (@vladpaiu) 33 19 1446 50
   4. Razvan Crainea (@razvancrainea) 17 14 150 48
   5. Vlad Patrascu (@rvlad-patrascu) 12 6 595 38
   6. Norman Brandinger (@NormB) 7 5 58 4
   7. Bogdan-Andrei Iancu (@bogdan-iancu) 7 5 7 5
   8. Maksym Sobolyev (@sobomax) 6 4 7 7
   9. jalung 5 1 144 61
   10. Norm Brandinger 4 1 207 5

   All remaining contributors: rdondeti, Dan Pascu (@danpascu),
   Ezequiel Lovelle, John Burke (@john08burke), tcresson, Eddie
   Fiorentine, Julián Moreno Patiño, Ken Rice, Peter Lemenkov
   (@lemenkov), zhengsh, Jarrod Baumann (@jarrodb), Kristian Høgh.

   (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. Regarding imported patches/code, we do our best
   to count the work on behalf of the proper owner, as per the
   "fix_authors" and "mod_renames" arrays in
   opensips/doc/build-contrib.sh. If you identify any
   patches/commits which do not get properly attributed to you,
   please submit a pull request which extends "fix_authors" and/or
   "mod_renames".

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

2.2. By Commit Activity

   Table 2.2. Most recently active contributors^(1) to this module
                    Name                 Commit Activity
   1.  Debian                          Mar 2026 - Mar 2026
   2.  rdondeti                        Mar 2026 - Mar 2026
   3.  Norman Brandinger (@NormB)      Mar 2026 - Feb 2026
   4.  Ken Rice                        Sep 2025 - Sep 2025
   5.  Razvan Crainea (@razvancrainea) Feb 2012 - May 2025
   6.  Norm Brandinger                 May 2025 - May 2025
   7.  Eddie Fiorentine                Mar 2025 - Mar 2025
   8.  Liviu Chircu (@liviuchircu)     Mar 2014 - Jan 2025
   9.  Vlad Paiu (@vladpaiu)           Oct 2011 - Nov 2024
   10. tcresson                        Oct 2023 - Oct 2023

   All remaining contributors: zhengsh, Maksym Sobolyev
   (@sobomax), John Burke (@john08burke), Vlad Patrascu
   (@rvlad-patrascu), Bogdan-Andrei Iancu (@bogdan-iancu), Dan
   Pascu (@danpascu), Peter Lemenkov (@lemenkov), Kristian Høgh,
   Julián Moreno Patiño, Jarrod Baumann (@jarrodb), jalung,
   Ezequiel Lovelle.

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

Chapter 3. Documentation

3.1. Contributors

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

Chapter 4. Frequently Asked Questions

   4.1.

   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!

   Documentation Copyrights:

   Copyright © 2011 www.opensips-solutions.com
