APEREO CASDocumentation

Enterprise Authentication for All Earthlings and Beyond

Identity, Single Sign-On and Access Management
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Configuration Management - Clustered Deployments

CAS uses the Spring Cloud Bus to manage configuration in a distributed deployment. Spring Cloud Bus links nodes of a distributed system with a lightweight message broker. This can then be used to broadcast state changes (e.g. configuration changes) or other management instructions.

The bus supports sending messages to all nodes listening. Broadcasted events will attempt to update, refresh and reload each CAS server application’s configuration.

If CAS nodes are not sharing a central location for configuration properties such that each node contains a copy of the settings, any changes you make to one node must be replicated and synced across all nodes so they are persisted on disk. The broadcast mechanism noted above only applies changes to the runtime and the running CAS instance. Ideally, you should be keeping track of CAS settings in a shared (git) repository (or better yet, inside a private GitHub repository perhaps) where you make a change in one place and it’s broadcasted to all nodes. This model removes the need for synchronizing changes across disks and CAS nodes.

The following settings and properties are available from the CAS configuration catalog:

spring.cloud.bus.ack.destination-serviceService that wants to listen to acks.
no default
Third party

Service that wants to listen to acks. By default null (meaning all services).

Type
String
Default
none
Defined by
BusProperties$Ack
spring.cloud.bus.ack.enabledFlag to switch off acks (default on).
true
Third party

Flag to switch off acks (default on).

Type
Boolean
Default
true
Defined by
BusProperties$Ack
spring.cloud.bus.content-typeThe bus mime-type.
no default
Third party

The bus mime-type.

Type
MimeType
Default
none
Defined by
BusProperties
spring.cloud.bus.destinationName of Spring Cloud Stream destination for messages.
no default
Third party

Name of Spring Cloud Stream destination for messages.

Type
String
Default
none
Defined by
BusProperties
spring.cloud.bus.enabledFlag to indicate that the bus is enabled.
true
Third party

Flag to indicate that the bus is enabled.

Type
Boolean
Default
true
Defined by
BusProperties
spring.cloud.bus.env.enabledFlag to switch off environment change events (default on).
true
Third party

Flag to switch off environment change events (default on).

Type
Boolean
Default
true
spring.cloud.bus.idThe identifier for this application instance.
application
Third party

The identifier for this application instance.

Type
String
Default
application
Defined by
BusProperties
spring.cloud.bus.refresh.enabledFlag to switch off refresh events (default on).
true
Third party

Flag to switch off refresh events (default on).

Type
Boolean
Default
true
spring.cloud.bus.shutdown.enabledFlag to switch off shutdown events (default on).
true
Third party

Flag to switch off shutdown events (default on).

Type
Boolean
Default
true
spring.cloud.bus.trace.enabledFlag to switch on tracing of acks (default off).
false
Third party

Flag to switch on tracing of acks (default off).

Type
Boolean
Default
false
Defined by
BusProperties$Trace

Required settings may be needed to activate or affect the feature; review them even when they have a default. Optional settings only need to be set to change a default or to turn on the behavior they control. Third party settings belong to libraries such as Spring Boot that CAS builds on; their own documentation may have more detail.

Notes on configuration

Configuration Metadata

The collection of configuration properties listed in this section are automatically generated from the CAS source and components that contain the actual field definitions, types, descriptions, modules, etc. This metadata may not always be 100% accurate, or could be lacking details and sufficient explanations.

Be Selective

This section is meant as a guide only. Do NOT copy/paste the entire collection of settings into your CAS configuration; rather pick only the properties that you need. Do NOT enable settings unless you are certain of their purpose and do NOT copy settings into your configuration only to keep them as reference. All these ideas lead to upgrade headaches, maintenance nightmares and premature aging.

YAGNI

Note that for nearly ALL use cases, declaring and configuring properties listed here is sufficient. You should NOT have to explicitly massage a CAS XML/Java/etc configuration file to design an authentication handler, create attribute release policies, etc. CAS at runtime will auto-configure all required changes for you. If you are unsure about the meaning of a given CAS setting, do NOT turn it on without hesitation. Review the codebase or better yet, ask questions to clarify the intended behavior.

Naming Convention

Property names can be specified in very relaxed terms. For instance cas.someProperty, cas.some-property, cas.some_property are all valid names. While all forms are accepted by CAS, there are certain components (in CAS and other frameworks used) whose activation at runtime is conditional on a property value, where this property is required to have been specified in CAS configuration using kebab case. This is both true for properties that are owned by CAS as well as those that might be presented to the system via an external library or framework such as Spring Boot, etc.

:information_source: Note

When possible, properties should be stored in lower-case kebab format, such as cas.property-name=value. The only possible exception to this rule is when naming actuator endpoints; The name of the actuator endpoints (i.e. ssoSessions) MUST remain in camelCase mode.

Settings and properties that are controlled by the CAS platform directly always begin with the prefix cas. All other settings are controlled and provided to CAS via other underlying frameworks and may have their own schemas and syntax. BE CAREFUL with the distinction. Unrecognized properties are rejected by CAS and/or frameworks upon which CAS depends. This means if you somehow misspell a property definition or fail to adhere to the dot-notation syntax and such, your setting is entirely refused by CAS and likely the feature it controls will never be activated in the way you intend.

Validation

Configuration properties are automatically validated on CAS startup to report issues with configuration binding, especially if defined CAS settings cannot be recognized or validated by the configuration schema. Additional validation processes are also handled via Configuration Metadata and property migrations applied automatically on startup by Spring Boot and family.

Indexed Settings

CAS settings able to accept multiple values are typically documented with an index, such as cas.some.setting[0]=value. The index [0] is meant to be incremented by the adopter to allow for distinct multiple configuration blocks.

Strategies

The following strategies are available to link the CAS nodes of a distributed deployment with a lightweight message broker, to broadcast state changes (such as configuration changes) or other management instructions.

Strategy Resource
AMQP See this guide.
Apache Kafka See this guide.

Actuator Endpoints

The following endpoints are provided by Spring Cloud:

features
Third-party endpoint1 operationNot exposed by default
refresh
Third-party endpoint1 operationNot exposed by default
busenv
Third-party endpoint2 operationsNot exposed by default
busrefresh
Third-party endpoint2 operationsNot exposed by default
busshutdown
Third-party endpoint2 operationsNot exposed by default
serviceregistry
Third-party endpoint2 operationsNot exposed by default
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Turn the endpoints on and expose them over the web. One entry covers every operation. By default only info, health and status are exposed.



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management.endpoint.features.access=UNRESTRICTED
management.endpoint.refresh.access=UNRESTRICTED
management.endpoint.busenv.access=UNRESTRICTED
management.endpoint.bus-refresh.access=UNRESTRICTED
management.endpoint.busrefresh.access=UNRESTRICTED
management.endpoint.busshutdown.access=UNRESTRICTED
management.endpoint.serviceregistry.access=UNRESTRICTED
management.endpoints.web.exposure.include=features,refresh,busenv,bus-refresh,busrefresh,busshutdown,serviceregistry

Endpoints may be mapped to other paths. For example, to serve health at healthcheck:



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management.endpoints.web.path-mapping.health=healthcheck

The transport mechanism for the bus to broadcast events is handled via one of the following components.

Troubleshooting

To enable additional logging, modify the logging configuration file to add the following:



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<Logger name="org.springframework.cloud.bus" level="debug" additivity="false">
    <AppenderRef ref="casConsole"/>
    <AppenderRef ref="casFile"/>
</Logger>