kumo.set_lruttl_cache_capacity
Since: Version 2025.03.19-1d3f1f67
The functionality described in this section requires version 2025.03.19-1d3f1f67 of KumoMTA, or a more recent version.
Allows you to configure the maximum capacity for a specific named pre-defined cache.
You may only update the capacity for caches defined inside kumomta's Rust code
via declare_cache!. Other caches are assumed to be dynamically created and
expose their capacity as part of their own individual configuration.
kumo.on('pre_init', function()
-- Increase the mx cache size from its default of 64*1024 to 128,000
kumo.set_lruttl_cache_capacity('dns_resolver_mx', 128000)
end)
Note
This function is intended to be used in pre_init, but it can be called
at any time. Reducing the capacity while the cache holds data will trigger
a partial eviction. The cache will eventually shrink to conform to the
new size as the cache is operated upon and background processing trims
the cache.
Below is a list of pre-defined caches and their default capacities in the
main branch. The list is automatically extracted from the code during the
documentation build, unversioned and may not reflect the version of KumoMTA
that you are running.
| Name | Capacity | Comment |
|---|---|---|
| dkim_key_cache | 1024 | Caches dkim loaded signing keys based on their KeySource spec |
| dkim_signer_cache | 1024 | Caches dkim signer specs to signer objects |
| dns_resolver_ip | 1024 | Caches domain name to the combined set of ipv4 and ipv6 records |
| dns_resolver_ipv4 | 1024 | Caches domain name to ipv4 records |
| dns_resolver_ipv6 | 1024 | Caches domain name to ipv6 records |
| dns_resolver_mx | 65536 | Caches domain name to computed set of MailExchanger records |
| egress_source_pools | 128 | Caches EgressPool information by pool name |
| egress_source_sources | 128 | Caches EgressSource information by source name |
| http_server_auth | 128 | Caches the results of the http server auth validation by auth credential |
| mod_filesystem_glob_cache | 32 | Caches glob results by glob pattern |
| mta_sts_policy | 65536 | Caches MTA-STS policy information by domain |
| rfc5321_rustls_config | 32 | Caches TLS connector information for the RFC5321 SMTP client |
| smtp_dispatcher_broken_tls | 65536 | Remembers which site names have broken TLS |
| smtp_dispatcher_client_certificate | 1024 | Caches smtp client certificates by KeySource spec |
| smtp_server_tls_config | 128 | Caches TLS acceptor information for the esmtp listener |