Configure the JVM DNS TTL

This guide explains how to configure the DNS Time-to-Live (TTL) settings for the Release Java Virtual Machine (JVM) in a Kubernetes environment. Proper TTL configuration is crucial for managing how long DNS resolutions are cached, which can affect system performance and network behavior.

Understanding JVM DNS Caching

The Release Java Virtual Machine (JVM) implements DNS caching to optimize hostname resolution performance. When the JVM resolves a hostname to an IP address, it stores this resolution in a cache for a configurable period, known as the Time-to-Live (TTL).

Default Configuration

By default, the TTL on Release images is set to 30 seconds. This setting is configured in the JVM's conf/security/security.properties file with the following parameter:

networkaddress.cache.ttl=30

TTL Values

• Setting TTL to -1 configures permanent caching
• Setting TTL to 0 disables caching entirely
• Any positive value represents the cache duration in seconds

Modifying TTL Settings

To change the default TTL value, you can modify the networkaddress.cache.ttl property through the operator CR configuration. For example, to set the TTL to 10 seconds:

kubectl patch -n digitalai digitalaireleases.xlr.digital.ai dai-xlr \
--type=merge --patch '{"jvm":{"options": {"networkaddress.cache.ttl": 10}}}'

After applying this change, the Release pods will automatically restart to apply the new TTL configuration.