Spring Cloud Kubernetes reload: decide which changes need a restart

Separate detection from application

A route limit changes in a ConfigMap. Spring Cloud Kubernetes can detect changes and trigger a refresh, restart or shutdown strategy, depending on configuration and version. A refreshed @ConfigurationProperties bean may see a new value, but a connection pool created from the old setting may not. Refresh boundaries need an inventory of stateful beans.

Use a rollout for hard state

Credential rotations, TLS material and connection targets often deserve a controlled pod restart with readiness gating. If a watcher is used, grant only the resources and namespace it monitors. The default reload setting is disabled in current Spring Cloud Kubernetes documentation; do not build an operational promise around an unstated default.

Observe the change

Patch one ConfigMap key, wait for the configured detection path, then call a behavior endpoint on every replica. Verify old requests finish, new requests use the intended value, and the pod remains ready. Also delete a key and check fallback behavior rather than assuming refresh restores its old value.

Implementation sketch

spring:
  cloud:
    kubernetes:
      reload:
        enabled: true
        monitoring-config-maps: true
        monitoring-secrets: false

Cost and verification

Event watchers hold API watches; polling produces repeated reads. Restarts trade brief capacity for a clean bean graph. Choose by measured change frequency and state ownership.

Common Mistakes

• Do not equate a watch event with a fully reconfigured application.
• Do not use live refresh for a bean that only reads configuration at construction time.
• Do not allow a rollout to drop readiness before in-flight work drains.

Read next

Spring Cloud Kubernetes config import: make source precedence explicit, Spring Cloud refresh: changed properties do not rebuild every dependency, Spring readiness during termination: stop routing before stopping dependencies.

Related boundary

Spring Cloud Kubernetes watcher scope: filter before broadcasting refresh