Metadata Query Protocol - SAML2 Metadata Management

CAS also supports the Metadata Query Protocol, also known as MDQ, which is a REST-like API for requesting and receiving arbitrary metadata. In order to configure a CAS SAML service to retrieve its metadata from a Metadata query server, the metadata location must be configured to point to the query server instance.

MDQ may be configured using the below snippet as an example:

{
  "@class" : "org.apereo.cas.support.saml.services.SamlRegisteredService",
  "serviceId" : "the-entity-id-of-the-sp",
  "name" : "SAMLService",
  "id" : 10000003,
  "evaluationOrder" : 10,
  "metadataLocation" : "https://mdq.server.org/entities/{0}"
}

…where {0} serves as an entityID placeholder for which metadata is to be queried. The placeholder is dynamically processed and replaced by CAS at runtime. Multiple locations may be comma-separated.

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

cas.authn.saml-idp.metadata.mdq.basic-authn-passwordBasic auth password in case the metadata instance is connecting to an MDQ server.

no default

Basic auth password in case the metadata instance is connecting to an MDQ server.

Type: String
Default: none
Defined by: MDQSamlMetadataProperties

cas.authn.saml-idp.metadata.mdq.basic-authn-usernameBasic auth username in case the metadata instance is connecting to an MDQ server.

no default

Basic auth username in case the metadata instance is connecting to an MDQ server.

Type: String
Default: none
Defined by: MDQSamlMetadataProperties

cas.authn.saml-idp.metadata.mdq.supported-content-typeThe media type this instance asks an MDQ server for, sent as the Accept header.

application/samlmetadata+xml

The media type this instance asks an MDQ server for, sent as the Accept header. The SAML profile for the Metadata Query Protocol requires a conforming client to request application/samlmetadata+xml, which is the default. Override it only for a server that serves SAML metadata under a different media type.

Type: String
Default: application/samlmetadata+xml
Defined by: MDQSamlMetadataProperties

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.

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.