Server Configuration Posts

Reading Original IP on Keycloak when Installed Behind a Reverse Proxy

Keycloak, or Red Hat Single SignOn, have the capability of capturing ip of every request which are connected to it. But there are scenarios where Keycloak is located behind a reverse proxy, and Keycloak would capture reverse proxy’s ip instead of original requestor IP.

The workaround is actually quite simple although can be at different xml files depends on your server , can add below configuration on default-server tag.

<server name="default-server">
	<http-listener name="default" socket-binding="http" redirect-socket="https" enable-http2="true"
		proxy-address-forwarding="true" />
	<https-listener name="https" socket-binding="https" security-realm="ApplicationRealm" enable-http2="true"
		proxy-address-forwarding="true" />
	<host name="default-host" alias="localhost">
		<location name="/" handler="welcome-content"/>
		<http-invoker security-realm="ApplicationRealm"/>

Starting JBoss EAP or Wildfly with a Specific XML Configuration

We can run EAP or Wildfly with a specific XML configuration, not just the default one. For example we have a new configuration with the name of standalone-full-ha_1.xml, and want to run EAP based on it. First we need to put corresponding XML on below directory,


And run using below command,

standalone.bat -c standalone-full-ha_1.xml



Monitoring Kafka Topics with Dockerized Kafka Manager

Yesterday, Dimas (one of my colleague), are asking me on how to monitor Kafka which are running on top of Openshift using a tools which are accessible thru browser.

One of the tools im recommending is Kafka Manager, which we can download from below url,

Lets start from the beginning, from how to start Zookeeper, Kafka Server, until simulate a simple produce and consume and monitoring it using Kafka Manager.

First, download Kafka from Apache site, extract it, and open bin folder. We need Zookeeper to start before we start anything else. Fyi for this example im using Win10 as my primary Operating System, so all my command below can be different depends on what Operating System you are using.

cd D:\software\kafka_2.13-2.4.0\bin\windows
zookeeper-server-start.bat ..\..\config\

And run Kafka Server afterwards,

kafka-server-start.bat ..\..\config\

Create a topic,

kafka-topics.bat --create --bootstrap-server localhost:9092 --replication-factor 1 --partitions 1 --topic my-testing-topic

Try produce a simple echo message using Kafka Producer,

kafka-console-producer.bat --broker-list localhost:9092 --topic my-testing-topic

And listen to the sent message using Kafka Consumer,

kafka-console-consumer.bat --bootstrap-server localhost:9092 -topic  my-testing-topic --from-beginning

If you only want to get all the new message, ignoring the old one, just remove “–from-beginning” parameter. And use “–offset” parameter to get a specific offset.

Next is running my Kafka Manager using Docker command. Fyi, is my laptop ip.

docker run --network host --add-host=moby: --add-host DESKTOP: -p 9000:9000 -e ZK_HOSTS=""  kafkamanager/kafka-manager

After Kafka-Manager is successfully started, we can browse our Kafka by opening thru browser,


Fixing Error “null username” when Integrating RedHat Single Sign On to Active Directory

Previously never had any issue when integrating RedHat SSO (Keycloak) to LDAP, but now got a very weird issue because now im trying to connecting RHSSO to Microsoft Active Directory instead of standard LDAP.

One biggest difference is that ActiveDirectory is using “sAMAccountName” field for user primarykey mapping, and somehow RHSSO is always get null value when trying to synchronize with existing user. Below is the complete stacktrace.

11:59:45,031 ERROR [] (default task-122) Failed during import user from LDAP: 
org.keycloak.models.ModelException: User returned from LDAP has null username! 
Check configuration of your LDAP mappings. Mapped username LDAP attribute: sAMAccountName, 
user DN: CN=XXX,OU=User,OU=HO,DC=llll,DC=co,DC=id, attributes from LDAP: 
{whenChanged=[20191016020643.0Z], whenCreated=[20170105023800.0Z], mail=[], givenName=[cccc], sn=[dddd], cn=[ccccc dddd], userAccountControl=[512], pwdLastSet=[132156652033202194]}
	at org.keycloak.models.utils.KeycloakModelUtils.runJobInTransaction(
	at org.keycloak.cluster.infinispan.InfinispanClusterProvider.executeIfNotExecuted(
	at org.keycloak.models.utils.KeycloakModelUtils.runJobInTransaction(
	at sun.reflect.GeneratedMethodAccessor891.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(
	at java.lang.reflect.Method.invoke(

It turns out that i have to mapping “sAMAccountName” field to username. Can find the complete screenshot below,

Cheers (^)


Error Apache HTTPD, No protocol handler was valid for the URL

Got weird error today when implementing apache httpd as a reverse proxy on my RHEL environment, here is the complere stacktrace

AH01144: No protocol handler was valid for the URL /url (scheme 'http'). 
If you are using a DSO version of mod_proxy, make sure the proxy submodules are included in the configuration using LoadModule.

The only module that i unremark on httpd.conf is

LoadModule proxy_module modules/

I found out that i need to unremark other module, that is mod_proxy_http

LoadModule proxy_http_module modules/

After unremarking mod_proxy_http, everything runs well.