| layout | title | category |
|---|---|---|
default |
CAS - Configuration Management - Reloading Changes |
Configuration |
{% include variables.html %}
The CAS spring cloud configuration server is able to consume properties and settings via the profiles outlined here. The server is constantly monitoring changes to the underlying property sources automatically, but has no way to broadcast those changes to its own clients, such as the CAS server itself, which would act as a client of the configuration server expecting change notifications to quietly reload its configuration.
Therefore, in order to broadcast such change events CAS
presents various endpoints that allow the adopter
to refresh the configuration as needed. This means that an adopter would
change a required CAS settings and then would submit
a request to CAS to refresh its current state. All CAS internal components that are affected
by the external change are quietly reloaded
and the setting takes immediate effect, completely removing the need for container restarts or CAS re-deployments.
Most if not all CAS settings are eligible candidates for reloads. CAS should be smart enough to reload the appropriate configuration, regardless of setting/module that ends up using that setting. All is fair game, as the entire CAS web application inclusive of all modules and all relevant settings may be completely and utterly reloadable. If you find an instance where this statement does not hold, please speak up.
CAS uses Spring Cloud to manage the internal state of the configuration. The configuration server that is provided by Spring Cloud embedded in CAS is constantly monitoring sources that house CAS settings and upon changes will auto-refresh itself.
The CAS application context and runtime environment that contains all Spring components and bean definitions can be reloaded using the following administrative endpoints:
{% include_cached actuators.html endpoints="features,refresh,busenv,butshotdown,bus-refresh,busrefresh,serviceregistry" %}
In the event that the standalone configuration profile is used to control and direct settings and Spring Cloud configuration server is disabled, CAS may begin to automatically watch and monitor the configuration files indicated by the profile and will auto-reload the state of the runtime application context automatically.
Support is enabled by including the following dependency in the WAR overlay:
{% include_cached casmodule.html group="org.apereo.cas" module="cas-server-core-events-configuration" %}
Spring application context will fail to refresh beans that are excluded (or conditionally activated/created) at
initialization/startup time, because there is nothing to refresh to begin with. Refresh requests and beans
marked with @RefreshScope only work in scenarios where there is an existing reference to a bean in the application
context hierarchy that can be refreshed; beans or configuration classes that are skipped during the startup and
application context initialization will never be refreshable, because they are not re-created upon refresh
requests. In other words, refresh requests only work best when there is a setting or property whose existing
value changes from A to B; if there was no A to begin with, or if A is being removed, refresh requests and the reload strategy may fall short.
The following endpoints are provided by CAS:
{% include_cached actuators.html endpoints="health" healthIndicators="refresh" %}