Overview

The functionality described here presents a dedicated integration strategy between CAS and AWS. Support is enabled by including the following dependency in the overlay:

implementation "org.apereo.cas:cas-server-support-aws:${project.'cas.version'}"
<dependency>
  <groupId>org.apereo.cas</groupId>
  <artifactId>cas-server-support-aws</artifactId>
  <version>${cas.version}</version>
</dependency>
dependencyManagement {
  imports {
    mavenBom "org.apereo.cas:cas-server-support-bom:${project.'cas.version'}"
  }
}

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

Configuration

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.amazon-sts.credential-access-key=
  • Use access-key provided by AWS to authenticate.

  • cas.amazon-sts.credential-secret-key=
  • Use secret key provided by AWS to authenticate.

  • cas.amazon-sts.endpoint=
  • AWS custom endpoint.

  • cas.amazon-sts.region=
  • AWS region used.

    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.

  • cas.amazon-sts.client-execution-timeout=10000
  • Client execution timeout.

    This settings supports the java.time.Duration syntax. The format of the value will be PTnHnMnS, where n is the relevant hours, minutes or seconds part of the duration. Any fractional seconds are placed after a decimal point in the seconds section. If a section has a zero value, it is omitted. The hours, minutes and seconds will all have the same sign. Example values could be in the form of PT20S, PT15M, PT10H, PT6D, P2DT3H4M. If the value is set to 0 or never, the duration will be set to zero. If the value is blank, set to -1, or infinite, the value will effectively represent an unending duration.
  • cas.amazon-sts.connection-timeout=5000
  • Connection timeout.

    This settings supports the java.time.Duration syntax. The format of the value will be PTnHnMnS, where n is the relevant hours, minutes or seconds part of the duration. Any fractional seconds are placed after a decimal point in the seconds section. If a section has a zero value, it is omitted. The hours, minutes and seconds will all have the same sign. Example values could be in the form of PT20S, PT15M, PT10H, PT6D, P2DT3H4M. If the value is set to 0 or never, the duration will be set to zero. If the value is blank, set to -1, or infinite, the value will effectively represent an unending duration.
  • cas.amazon-sts.local-address=
  • Local address.

  • cas.amazon-sts.max-connections=10
  • Maximum connections setting.

  • cas.amazon-sts.principal-attribute-name=
  • Attribute name that must be found and resolved for the principal to authorize the user to proceed with obtaining credentials.

  • cas.amazon-sts.principal-attribute-value=
  • Attribute value, defined as a regex pattern that must be found and resolved for the principal to authorize the user to proceed with obtaining credentials.

  • cas.amazon-sts.profile-name=
  • Profile name to use.

  • cas.amazon-sts.profile-path=
  • Profile path.

  • cas.amazon-sts.proxy-host=
  • Optionally specifies the proxy host to connect through.

  • cas.amazon-sts.proxy-password=
  • Optionally specifies the proxy password to connect through.

  • cas.amazon-sts.proxy-username=
  • Optionally specifies the proxy username to connect through.

  • cas.amazon-sts.rbac-enabled=false
  • When set to true, credentials will be obtained based on roles as attributes resolved for the user. Typically, you could use roles wthin your account or for cross-account access.

    When set to true, the #getPrincipalAttributeName() must contain roleArns as values.

  • cas.amazon-sts.retry-mode=STANDARD
  • Outline the requested retry mode. Accepted values are STANDARD, LEGACY.

  • cas.amazon-sts.socket-timeout=5000
  • Socket timeout.

    This settings supports the java.time.Duration syntax. The format of the value will be PTnHnMnS, where n is the relevant hours, minutes or seconds part of the duration. Any fractional seconds are placed after a decimal point in the seconds section. If a section has a zero value, it is omitted. The hours, minutes and seconds will all have the same sign. Example values could be in the form of PT20S, PT15M, PT10H, PT6D, P2DT3H4M. If the value is set to 0 or never, the duration will be set to zero. If the value is blank, set to -1, or infinite, the value will effectively represent an unending duration.
  • cas.amazon-sts.use-reaper=false
  • Flag that indicates whether to use reaper.

    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 below 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.S ettings 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.

    Administrative Endpoints

    The following endpoints are provided by CAS:

    Endpoint Description
    awsSts Obtain temporary AWS access credentials via POST. Can accept a duration parameter to specify the expiration policy for the credentials. User credentials can be provided in the POST request body via username and password parameters similar to the CAS REST protocol. The endpoint support all available multifactor authentication triggers. When using roles, a roleArn parameter can pre-select the role for the authenticated principal, if more than one role attribute value is found and resolved.

    Temporary Security Credentials

    For convenience you can simply copy and paste the temporary AWS access credentials generated above to set them as environment variables or save the output into ~/.aws/credentials that would be loaded and recognized by AWS CLI given the profile name.

    The AWS CLI stores sensitive credential information that you specify with aws configure in a local file named credentials, in a folder named .aws in your home directory. The less sensitive configuration options that you specify with aws configure are stored in a local file named config, also stored in the .aws folder in your home directory.

    To learn more about AWS CLI, please see this guide.

    Obtaining temporary security credentials can be done using the following integration strategies.

    Roles

    Obtaining temporary security credentials from AWS STS is done using the AssumeRole API operation. Typically, you use this API within your account or for cross-account access.

    The temporary security credentials created by this operation can be used to make API calls to any AWS service with the exception of AWS STS GetFederationToken or GetSessionToken API operations.

    To assume a role from a different account, your AWS account must be trusted by the role. The trust relationship is defined in the role’s trust policy when the role is created. That trust policy states which accounts are allowed to delegate that access to users in the account. A user who wants to access a role in a different account must also have permissions that are delegated from the user account administrator. The administrator must attach a policy that allows the user to call this operation for the ARN of the role in the other account.

    Roles are expected to be found under a pre-defined attribute for the principal. If more than one role is found, a pre-selected role can be specified using the roleArn parameter. The session name for the role is automatically generated by CAS. Role attribute values are expected to be in the format of [\u0009\u000A\u000D\u0020-\u007E\u0085\u00A0-\uD7FF\uE000-\uFFFD\u10000-\u10FFFF]+

    Session Tokens

    Obtaining temporary security credentials from AWS STS is done using the GetSessionToken API operation. The primary occasion for calling this operation is when a user must be authenticated with multi-factor authentication (MFA). The authenticated user can qualify and initiate multifactor authentication using the available multifactor authentication triggers.

    On required permissions Amazon Web Services states,

    No permissions are required for a user to get a session token. The purpose of the API operation is to authenticate the user using MFA. You cannot use policies to control authentication operations.

    Granted Permissions

    On granted permissions Amazon Web Services states,

    If the API is called with the credentials of an IAM user, the temporary security credentials have the same permissions as the IAM user. Similarly, if the API is called with AWS account root user credentials, the temporary security credentials have root user permissions.

    AWS recommends that you do not call the API with root user credentials. Instead, create IAM users with the permissions they need. Then use these IAM users for everyday interaction with AWS.

    Note that you cannot use the credentials to call IAM or AWS STS API operations. You can use them to call API operations for other AWS services.