Overview

Google Apps for Education (or any of the Google Apps) utilizes SAML 2.0 to provide an integration point for external authentication services.

Usage

The Google Apps for Education integration described here allows CAS to act as a miniaturized SAML2 identity provider, for deployments that may not be prepared to turn on and allow CAS to fully act as a SAML2 identity provider. This feature is deprecated and is scheduled to be removed in the future. It does not make much sense to turn on and use both features in CAS at the same time, as one outranks the other and it is likely that using both features in CAS simultaneously would interfere with the functionality of both. If you can, consider using the SAML2 identity provider functionality in CAS to handle this integration as you would any other SAML2 service provider.

Support is enabled by including the following dependency in the WAR overlay:

<dependency>
    <groupId>org.apereo.cas</groupId>
    <artifactId>cas-server-support-saml-googleapps</artifactId>
    <version>${cas.version}</version>
</dependency>

implementation "org.apereo.cas:cas-server-support-saml-googleapps:${project.'cas.version'}"

dependencyManagement {
    imports {
        mavenBom "org.apereo.cas:cas-server-support-bom:${project.'cas.version'}"
    }
}

dependencies {
    implementation "org.apereo.cas:cas-server-support-saml-googleapps"
}

dependencies {
    /*
    The following platform references should be included automatically and are listed here for reference only.
            
    implementation enforcedPlatform("org.apereo.cas:cas-server-support-bom:${project.'cas.version'}")
    implementation platform(org.springframework.boot.gradle.plugin.SpringBootPlugin.BOM_COORDINATES)
    */

    implementation "org.apereo.cas:cas-server-support-saml-googleapps"
}

Generate Public/Private Keys

The first step is to generate DSA/RSA public and private keys. These are used to sign and read the Assertions. After keys are created, the public key needs to be registered with Google.

The keys will also need to be available to the CAS application (but not publicly available over the Internet) via the classpath though any location accessible by the user running the web server instance and not served publicly to the Internet is acceptable. Thus, inside src/main/resources is nice because it is scoped to the web application but not normally served. /etc/cas/ is also fine as well and protects the key from being overwritten on deploy of a new CAS webapp version.

openssl genrsa -out private.key 1024
openssl rsa -pubout -in private.key -out public.key -inform PEM -outform DER
openssl pkcs8 -topk8 -inform PER -outform DER -nocrypt -in private.key -out private.p8
openssl req -new -x509 -key private.key -out x509.pem -days 365

The x509.pem file should be uploaded into Google Apps under Security/SSO.

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

_{The configuration settings listed below are tagged as Required in the CAS configuration metadata. This flag indicates that the presence of the setting may be needed to activate or affect the behavior of the CAS feature and generally should be reviewed, possibly owned and adjusted. If the setting is assigned a default value, you do not need to strictly put the setting in your copy of the configuration, but should review it nonetheless to make sure it matches your deployment expectations.}

cas.google-apps.private-key-location=file:/etc/cas/private.key

The private key location that is used to sign responses, etc. Deprecation: Since 6.2

org.apereo.cas.configuration.model.support.saml.googleapps.GoogleAppsProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

: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.

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.google-apps.private-key-location=file:/etc/cas/private.key

This is the most common form of property configuration that is recognized by CAS, regardless of the actual property source, which might in fact be managed separately outside the CAS environment, by another system or cloud framework.

CAS properties can be specified using the YAML syntax:

cas: 
  google-apps: 
    private-key-location: "file:/etc/cas/private.key"

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.google-apps.private-key-location="file:/etc/cas/private.key" -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory. Note the placement of the system property which must be specified before the CAS web application is launched.

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_GOOGLE_APPS_PRIVATE_KEY_LOCATION="file:/etc/cas/private.key"

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.google-apps.private-key-location="file:/etc/cas/private.key"

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

Deprecation status is ERRORwithout a replacement setting.

cas.google-apps.public-key-location=file:/etc/cas/public.key

The public key location that is also shared with google apps. Deprecation: Since 6.2

org.apereo.cas.configuration.model.support.saml.googleapps.GoogleAppsProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

:information_source: Note

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.google-apps.public-key-location=file:/etc/cas/public.key

CAS properties can be specified using the YAML syntax:

cas: 
  google-apps: 
    public-key-location: "file:/etc/cas/public.key"

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.google-apps.public-key-location="file:/etc/cas/public.key" -jar build/libs/cas.war

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_GOOGLE_APPS_PUBLIC_KEY_LOCATION="file:/etc/cas/public.key"

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.google-apps.public-key-location="file:/etc/cas/public.key"

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

Deprecation status is ERRORwithout a replacement setting.

_{The configuration settings listed below are tagged as Optional in the CAS configuration metadata. This
flag indicates that the presence of the setting
is not immediately necessary in the end-user CAS configuration, because a default value is assigned or
the activation of the feature is not conditionally controlled by the setting value. You should only include this field in your
configuration if you need to modify the default value.}

cas.google-apps.key-algorithm=RSA

Signature algorithm used to generate keys. Deprecation: Since 6.2

org.apereo.cas.configuration.model.support.saml.googleapps.GoogleAppsProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

:information_source: Note

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.google-apps.key-algorithm=RSA

CAS properties can be specified using the YAML syntax:

cas: 
  google-apps: 
    key-algorithm: "RSA"

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.google-apps.key-algorithm="RSA" -jar build/libs/cas.war

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_GOOGLE_APPS_KEY_ALGORITHM="RSA"

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.google-apps.key-algorithm="RSA"

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

Deprecation status is ERRORwithout a replacement setting.

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.

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. The validation process is on by default and can be skipped on startup using a special system property SKIP_CONFIG_VALIDATION that should be set to true. 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.

Register Google Apps

Ensure that Google Apps is registered in your service registry.

{
  "@class" : "org.apereo.cas.services.CasRegisteredService",
  "serviceId" : "https://www.google.com/a/YourGoogleDomain/acs",
  "name" : "googleApps",
  "id" : 1000,
  "evaluationOrder" : 10
}

Configure Username Attribute

As an optional step, you can configure an alternate username to be send to Google in the SAML reply. This alternate user name can be specified in the CAS service registry via username attribute providers for the registered Google Apps service.

Configure Google

You’ll need to provide Google with the URL for your SAML-based SSO service, as well as the URL your users will be redirected to when they log out of a hosted Google application. Use the following URLs when you are configuring for Google Apps:

Sign-in page URL: https://sso.school.edu/cas/login
Sign-out page URL: https://sso.school.edu/cas/logout
Change password URL: https://mgmt.password.edu/

Test

Attempt to access a Google-hosted application, such as Google Calendar with the url: https://calendar.google.com/a/YourGoogleDomain