WAR Overlay Initializr

Apereo CAS Initializr is a relatively new addition to the Apereo CAS ecosystem that allows you as the deployer to generate CAS WAR Overlay projects on the fly with just what you need to start quickly.

To get started with a CAS deployment, adopters typically start with a plain Gradle-based overlay project and use that as a baseline for future modifications. While this has been the traditional and recommended approach for many years, it can also be rather challenging for a relatively-novice user new to the ecosystem to download, modify and prepare an overlay project to include all required customizations. Given the overlay project’s static nature, it can also be challenging for project owners and maintainers to keep it up-to-date or offer additional enhancements and automation without affecting the baseline template.

To address such scenarios, the CAS WAR Overlay Initializr offers a fast way to pull in all the dependencies and modules needed for a CAS deployment and provides friendly and programmatic curl-friendly API to generate an overlay structure and required build files.

The underlying framework that handles the project generation task is based on Spring Initializr.


The CAS Initializr can dynamically generate a starting project based on requested modules and dependencies needed for a deployment. This behavior can be tailored to the user’s experience based on that input and the conditions that follow to generate additional references, files, starting templates, and more in the same project to make the deployment process more comfortable.

CAS Initializr at this point is mainly a backend service and a few APIs. However, one could imagine that a graphical and modern user interface could be built on top of available APIs to help with the project generation task, especially for project newcomers.

Managing and maintaining a separate overlay projects and keeping them in sync with various CAS versions can be a costly maintenance task. CAS Initializr allows the project developers to automate the maintenance task, keep everything in the same repository for faster and more accurate upgrades.

CAS Initializr is used internally by the CAS project itself in a very Eat What You Kill type of way to dynamically generate overlay projects. These generated projects are used as CAS base Docker images published to Docker Hub, and as a baseline for browser/UI tests run by the CAS CI for each relevant feature. CAS Initializr uses itself to test itself!

To properly initialize and generate a CAS overlay, you may want to make sure you have curl, http and/or jq installed.

Project Types

The CAS Initializr can be invoked using curl to generate different types of overlay projects. The project selection is indicated using a type parameter. The following types are supported:

Type Description
cas-overlay Default; generates a CAS WAR overlay.
cas-bootadmin-server-overlay Generates a WAR Overlay for the Spring Boot Admin Server.
cas-config-server-overlay Generates a WAR Overlay for the Spring Cloud Configuration Server.
cas-discovery-server-overlay Generates a WAR Overlay for the Service Discovery Server.
cas-management-overlay Generates a WAR Overlay for the CAS Management Web Application.

Project Versions

The CAS Initializr can be instructed to prepare an overlay project for a specific version. The following request parameters control the version selection:

Type Description
casVersion Specify the CAS version for the overlay.
bootVersion Specify the Spring Boot version for the overlay.

Note that mixing and matching different versions generally will lead to unstable projects builds. Do so at your own risk! The specification of version numbers in the project generation request is unnecessary, and CAS Initializr will always use trusted defaults to handle the generation task.

To review the list of supported versions for the CAS Initializr on Heroku, you may use:

curl https://casinit.herokuapp.com/actuator/supportedVersions | jq

Source Code

CAS Initializr is available at:

Source Repository Location Heroku
https://github.com/apereo/cas-initializr Link

Project Generation

The CAS Initializr can be invoked using curl to generate an overlay project. To access the CAS Initializr, the following strategies can be used.


The CAS projects provides a public free instance of the CAS Initializr on Heroku, paid for by the Apereo CAS support subscribers. To get started with this instance, a simple way might be to include the following function in your bash profile:

function getcas(){
    curl https://casinit.herokuapp.com/starter.tgz \
      -d type=cas-overlay -d baseDir=overlay -d dependencies="$1" | tar -xzvf -

If you prefer, you could invoke the /starter.zip endpoint to get back a ZIP file instead.

This allows you to generate a CAS overlay project in the overlay directory using:

getcas duo,oidc

…which generates a CAS overlay project prepared with multifactor authentication by Duo Security and support for OpenID Connect.


To help keep the deployment costs down, the Heroku instance has turned on support for rate-limiting requests. Be aware that frequent requests may be throttled for access.


In case the Initializr is not available on Heroku, you can also run your own Initializr instance via Docker:

docker run --rm -p 8080:8080 apereo/cas-initializr:${tag}

The CAS Initializr should become available at http://localhost:8080 and will respond to API requests using curl. Published images and tags of the CAS Initializr can be found here.

CAS Modules

CAS project modules and dependencies that can be requested must be specified by their identifier. To see a full list of all dependencies supported and available by this service, you can invoke the following command:

curl https://casinit.herokuapp.com/dependencies

Typically, dependency identifiers match CAS server dependency/module artifact names without the cas-server- prefix. Furthermore, certain dependencies are assigned aliases as shortcuts to simplify requests. To see the full list of dependencies and their aliases, you may use:

curl https://casinit.herokuapp.com/actuator/info | jq

Furthermore, CAS Initializr publishes metadata about its capabilities, that is the available options for all request parameters (dependencies, type, etc.) A client to the service uses that information to initialize the select options and the tree of available dependencies.

You can grab the metadata on the root endpoint with the appropriate Accept header:

curl -H 'Accept: application/json' https://casinit.herokuapp.com | jq

Or using HTTPie:

http https://casinit.herokuapp.com Accept:application/json | jq

Dependency Management

CAS Initializr is set to use the CAS BOM for dependency management.


Please see this guide for more details.