How to fix Keycloak overlay installation failure

While playing with keycloak I have encountered several related problems:

1. Keycloak 3.2.1 downloadable with samples is not working running.
2. Installing keycloak 3.2.1 overlay on Wildfly 10.1.Final fails.

Errors are:

• Caused by: org.jboss.modules.ModuleNotFoundException: org.keycloak.keycloak-server-subsystem:main
• "WFLYCTL0310: Extension module org.keycloak.keycloak-server-subsystem not found".

Solution:

1. Inside WILDFLY_HOME\modules folder, create a new file layers.conf.
2. Content of the file should be:
   layers=keycloak