Attribute Definitions
The definition of an attribute in CAS, when fetched and resolved from an authentication or attribute repository source, tends to be defined
and referenced using its name without any additional metadata or decorations. For example, you may wish to retrieve a uid
attribute and virtually
rename and map it to a userIdentifier
attribute either globally or for specific application integrations. For most use cases, this configuration
works quite comfortably and yet, depending on the nature of the target application and the authentication protocol used to complete the integration,
additional requirements could be imposed and may have to be specified to define an attribute with
additional pointers, when shared and released with a relying party. For example, a
SAML2 service provider may require a scoped attribute for an eduPersonPrincipalName
whose value
is always determined from the uid
attribute with a special friendly-name that is always provided regardless of the target application.
While bits and pieces of metadata about a given attribute can be defined either globally in CAS configuration settings or defined inside a service definition, an attribute definition store allows one to describe metadata about necessary attributes with special decorations to be considered during attribute resolution and release. The specification of the attribute definition store is entirely optional and the store may not contain any attribute definitions.
The following settings and properties are available from the CAS configuration catalog:
cas.authn.attribute-repository.attribute-definition-store.json.location=
The location of the resource. Resources can be URLs, or files found either on the classpath or outside somewhere in the file system. In the event the configured resource is a Groovy script, specially if the script set to reload on changes, you may need to adjust the total number ofinotify instances. On Linux, you may need to add the following line to /etc/sysctl.conf : fs.inotify.max_user_instances = 256 . You can check the current value via cat /proc/sys/fs/inotify/max_user_instances . In situations and scenarios where CAS is able to automatically watch the underlying resource for changes and detect updates and modifications dynamically, you may be able to specify the following setting as either an environment variable or system property with a value of false to disable the resource watcher: org.apereo.cas.util.io.PathWatcherService .
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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.
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, specially 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.
JSON Attribute Definitions
Attribute definitions may be defined inside a JSON file whose location is provided via CAS settings. The structure of the JSON file may match the following:
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{
"@class" : "java.util.TreeMap",
"employeeId" : {
"@class" : "org.apereo.cas.authentication.attribute.DefaultAttributeDefinition",
"key" : "employeeId",
"scoped" : true,
"attribute" : "empl_identifier"
}
}
Generally-speaking, attribute definitions are specified using a Map
whose key is the
attribute name, as resolved by the CAS attribute resolution engine.
The attribute name as the key to the Map
must match the key
attribute of the attribute definition itself.
If the attribute in question is not already resolved as principal attribute with a valid set of values,
it might be possible, depending on the attribute release policy, to
resolve and create that attribute on the fly as an attribute definition that can produce values.
Please note that as of this writing, attribute definitions cannot be used to drive authorization decisions via the likes of RBAC. Such definitions are typically evaluated during the attribute release phase which is too late for authorization decisions. If you need to produce attributes specifically for authorization decisions, consider defining a specific attribute repository which would be evaluated during the attribute resolution phase instead.
The following settings can be specified by an attribute definition:
Name | Description |
---|---|
key |
Attribute name, as resolved by the CAS attribute resolution engine. |
name |
Comma-separated list of attribute name(s) to virtually rename/remap and share with the target application during attribute release. |
scoped |
(Optional) If true , the attribute value will be scoped to the scope of the CAS server deployment defined in settings. |
encrypted |
(Optional) If true , the attribute value will be encrypted and encoded in base-64 using the service definition’s defined public key. |
attribute |
(Optional) The source attribute to provide values for the attribute definition itself, replacing that of the original source. |
patternFormat |
(Optional) Template used in a java.text.MessageFormat to decorate the attribute values. |
script |
(Optional) Groovy script, external or embedded to process and produce attributes values. This field supports the Spring Expression Language syntax. |
canonicalizationMode |
(Optional) Control transformation of attribute values; allowed values are UPPER , LOWER or NONE . |
patterns |
(Optional) A map of regular expression patterns to static/dynamic constructs to build values, in scenarios where the attribute definition is built off of an existing attribute. |
flattened |
(Optional) Indicate whether attribute definitions with multiple values should be flattened into a single value, separated by the assigned delimiter. |
singleValue |
(Optional) Default is false . Determines if the attribute should be produced as a single-value claim if it has only a single value. |
The following operations in the order given should take place, if an attribute definition is to produce values:
- Produce attribute values based on the
attribute
setting specified in the attribute definition, if any. - Produce attribute values based on the
script
setting specified in the attribute definition, if any. - Produce attribute values based on the
patterns
setting specified in the attribute definition, if any. - Produce attribute values based on the
scoped
setting specified in the attribute definition, if any. - Produce attribute values based on the
patternFormat
setting specified in the attribute definition, if any. - Produce attribute values based on the
encrypted
setting specified in the attribute definition, if any. - Produce attribute values based on the
canonicalizationMode
setting specified in the attribute definition, if any. - Produce attribute values based on the
flattened
setting specified in the attribute definition, if any.
- Basic
- Encrypted
- Pattern Format
- Embedded Script
- External Script
- Regular Expression Patterns
- Flattened
-
Define an attribute definition for
employeeId
to produce scoped attributes based on another attributeempl_identifier
as the source:1 2 3 4 5 6 7 8 9
{ "@class" : "java.util.TreeMap", "employeeId" : { "@class" : "org.apereo.cas.authentication.attribute.DefaultAttributeDefinition", "key" : "employeeId", "scoped" : true, "attribute" : "empl_identifier" } }
Now that the definition is available globally, the attribute can then be released as usual with the following definition:
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... "attributeReleasePolicy" : { "@class" : "org.apereo.cas.services.ReturnAllowedAttributeReleasePolicy", "allowedAttributes" : [ "java.util.ArrayList", [ "employeeId" ] ] } ...
-
Same use case as above, except the attribute value will be encrypted and encoded using the service definition’s public key:
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{ "@class" : "java.util.TreeMap", "employeeId" : { "@class" : "org.apereo.cas.authentication.attribute.DefaultAttributeDefinition", "key" : "employeeId", "encrypted" : true, "attribute" : "empl_identifier" } }
The service definition should have specified a public key definition:
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... "publicKey" : { "@class" : "org.apereo.cas.services.RegisteredServicePublicKeyImpl", "location" : "classpath:public.key", "algorithm" : "RSA" } ...
The keys can be generated via the following commands:
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openssl genrsa -out private.key 1024 openssl rsa -pubout -in private.key -out public.key -inform PEM -outform DER openssl pkcs8 -topk8 -inform PEM -outform DER -nocrypt -in private.key -out private.p8
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Define an attribute definition to produce values based on a pattern format:
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{ "@class" : "java.util.TreeMap", "eduPersonPrincipalName" : { "@class" : "org.apereo.cas.authentication.attribute.DefaultAttributeDefinition", "key" : "eduPersonPrincipalName", "name" : "urn:oid:1.3.6.1.4.1.5923.1.1.1.6", "friendlyName" : "eduPersonPrincipalName", "scoped" : true, "patternFormat": "hello,{0}", "attribute" : "uid" } }
If the resolved set of attributes are
uid=[test1, test2]
and the CAS server has a scope ofexample.org
, the final values ofeduPersonPrincipalName
would be [hello,test1@example.org
,hello,test2@example.org
] released asurn:oid:1.3.6.1.4.1.5923.1.1.1.6
with a friendly name ofeduPersonPrincipalName
. -
Same use case as above, except the attribute value be additional processed by an embedded Groovy script
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{ "@class" : "java.util.TreeMap", "eduPersonPrincipalName" : { "@class" : "org.apereo.cas.authentication.attribute.DefaultAttributeDefinition", "key" : "eduPersonPrincipalName", "name" : "urn:oid:1.3.6.1.4.1.5923.1.1.1.6", "friendlyName" : "eduPersonPrincipalName", "scoped" : true, "script": "groovy { logger.info(\" name: ${attributeName}, values: ${attributeValues} \"); return ['Hi', attributes['firstname']] }" } }
If the CAS server has a scope of
example.org
, the final values ofeduPersonPrincipalName
would be [Hi, casuser
] released asurn:oid:1.3.6.1.4.1.5923.1.1.1.6
with a friendly name ofeduPersonPrincipalName
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Same use case as above, except the attribute value be additionally processed by an external Groovy script:
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{ "@class" : "java.util.TreeMap", "eduPersonPrincipalName" : { "@class" : "org.apereo.cas.authentication.attribute.DefaultAttributeDefinition", "key" : "eduPersonPrincipalName", "name" : "urn:oid:1.3.6.1.4.1.5923.1.1.1.6", "friendlyName" : "eduPersonPrincipalName", "scoped" : true, "script": "file:/attribute-definitions.groovy" } }
The outline of the Groovy script should be defined as:
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def run(Object[] args) { def (attributeName,attributeValues,logger,registeredService,attributes) = args logger.info("name: ${attributeName}, values: ${attributeValues}, attributes: ${attributes}") return ["Hello " + attributes['givenName']] }
If the CAS server has a scope of
example.org
, the final values ofeduPersonPrincipalName
would be [Hello casuser
] released asurn:oid:1.3.6.1.4.1.5923.1.1.1.6
with a friendly name ofeduPersonPrincipalName
. -
Define an attribute definition to produce values conditionally based on pattern matching rules. If the attribute definition is to build its values off of an existing resolved attribute, each available value is examined against patterns defined here in the
patterns
map. For each match, the linked entry is used to determine the attribute definition value, either statically or dynamically which is typically an inlined Groovy script. If a pattern match is not found, then the value is skipped.1 2 3 4 5 6 7 8 9 10 11 12 13 14
{ "@class" : "java.util.TreeMap", "memberships" : { "@class" : "org.apereo.cas.authentication.attribute.DefaultAttributeDefinition", "key": "memberships", "attribute" : "memberships", "name": "affiliations", "patterns" : { "@class" : "java.util.TreeMap", "m[0-2].*" : "admins", "m[3-6].*" : "groovy { return 'users' }" } } }
The above snippet builds an attribute definition,
memberships
, that is ultimately encoded and released to applications under the nameaffiliations
. The attribute values for this definition are sourced from thememberships
attribute that must be made available to CAS. Each value is examined against the patterns defined and on a successful match, the linked construct will be evaluated to determine the final value.For example, if the resolved set of attributes are
memberships=[m1, m2, m3, m4, m9]
, the final values ofmemberships
would be [admins
,users
] which would then be released under the nameaffiliations
.To prepare CAS to support and integrate with Apache Groovy, please review this guide.
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If the collection of attributes values assembled for the attribute definition ultimately contain more than one value, the attribute definition may be instructed to flatten all values using the given delimiter character into a single value.
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{ "@class" : "java.util.TreeMap", "allgroups" : { "@class" : "org.apereo.cas.authentication.attribute.DefaultAttributeDefinition", "key": "allgroups", "attribute" : "memberships", "flattened": "/" } }
For example, if the resolved set of attributes are
memberships=[m1, m2, m3, m4, m9]
, the final values ofmemberships
would bem1/m2/m3/m4
.
Custom Attribute Definitions
You may design and inject your own attribute definitions dynamically with CAS. First, you will need to design
a @AutoConfiguration
class to contain your own AttributeDefinitionStoreConfigurer
implementation:
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@AutoConfiguration
public class MyConfiguration {
@Bean
public AttributeDefinitionStoreConfigurer myAttributeDefinitionStore() {
...
}
}
Your configuration class needs to be registered with CAS. See this guide for better details.