deployment-overlay add --name=myOverlay --content=/WEB-INF/web.xml=/myFiles/myWeb.xml,/WEB-INF/ejb-jar.xml=/myFiles/myEjbJar.xml --deployments=test.war,*-admin.war --redeploy-affected
Deployment overlays are the way of 'overlaying' content into an existing deployment, without physically modifying the contents of the deployment archive. Possible use cases include swapping out deployment descriptors, modifying static web resources to change the branding of an application, or even replacing jar libraries with different versions (jars do not work until https://issues.jboss.org/browse/WFLY-1359 is fixed)
Deployment overlays have a different lifecycle to a deployment. In order to use a deployment overlay, you first create the overlay, using the CLI or the management API. You then add files to the overlay, specifying the deployment paths you want them to overlay. Once you have created the overlay you then have to link it to a deployment name (which is done slightly differently depending on if you are in standalone or domain mode). Once you have created the link any deployment that matches the specified deployment name will have the overlay applied.
When you modify or create an overlay it will not affect existing deployments, they must be redeployed in order to take effect
To create a deployment overlay the CLI provides a high level command to do all the steps specified above in one go. An example command is given below for both standalone and domain mode:
deployment-overlay add --name=myOverlay --content=/WEB-INF/web.xml=/myFiles/myWeb.xml,/WEB-INF/ejb-jar.xml=/myFiles/myEjbJar.xml --deployments=test.war,*-admin.war --redeploy-affected
deployment-overlay add --name=myOverlay --content=/WEB-INF/web.xml=/myFiles/myWeb.xml,/WEB-INF/ejb-jar.xml=/myFiles/myEjbJar.xml --deployments=test.war,*-admin.war --server-groups=main-server-group --redeploy-affected