[keycloak-user] keycloak docker image clustering section is not working as expected

[Meissa M'baye Sakho]

Hello everyone,
There a confusing section in the clustering [1] section of the keycloak
docker image.
The documentation states that:

*JGROUPS_DISCOVERY_PROPERTIES - an optional parameter with the discovery
protocol properties in the following format:  *
*PROP1=FOO,PROP2=BAR *

I can confirm that this parameter is not optional at all.
When I run the image  with the JGROUPS_DISCOVERY_PROTOCOL environnement
variable set and without the JGROUPS_DISCOVERY_PROPERTIES set (since it's
said to be optionnal), the container fails to start with the error message
below:
*10:50:11,999 ERROR [org.jboss.as.controller.management-operation]
(Controller Boot Thread) WFLYCTL0013: Operation ("add") failed - address:
([*
*    ("subsystem" => "jgroups"),*
*    ("channel" => "ee")*
*]) - failure description: {"WFLYCTL0080: Failed services" =>
{"org.wildfly.clustering.jgroups.channel.ee
<http://org.wildfly.clustering.jgroups.channel.ee>" =>
"java.lang.IllegalArgumentException: dns_query can not be null or empty*
*    Caused by: java.lang.IllegalArgumentException: dns_query can not be
null or empty"}}*

Setting the JGROUPS_DISCOVERY_PROPERTIES  environnement variable fix the
error. So this is not an optional parameter.
[1]=https://hub.docker.com/r/jboss/keycloak/

Regards,
Meissa