[[Web_Single_Sign_On]]
= Web Single Sign-On

This document will guide on how to enable single sign-on across different applications deployed into different servers, where these applications belong to same security domain.

== Create a Server Configuration Template

For this document, you'll need to run at least two server instances in order to check single sign-on and how it affect usability in your applications. Users should be able to log in once and have access to any application using the same security domain.

All configuration described in the next sections should be done with a server instance using *standalone-ha.xml* (or standalone-full-ha.xml).

Run a server instance using the following command:

----
bin/standalone.sh -c standalone-ha.xml
----

=== Create a HTTP Authentication Factory

IMPORTANT: If you already have a _http-authentication-factory_&nbsp;defined in Elytron subsystem and just want to use it to enable single sign-on to your applications, please skip this section.{info}
First, you need a _security-domain_ which we'll use to authenticate users. Please, execute the following CLI commands:

----
# Creates a FileSystem Realm, an identity store where users are stored in the local filesystem
/subsystem=elytron/filesystem-realm=example-realm:add(path=/tmp/example-realm)

# Creates a Security Domain
/subsystem=elytron/security-domain=example-domain:add(default-realm=example-realm, permission-mapper=default-permission-mapper,realms=[{realm=example-realm, role-decoder=groups-to-roles}]

# Creates an user that you can use to access your applications
/subsystem=elytron/filesystem-realm=example-realm:add-identity(identity=alice)
/subsystem=elytron/filesystem-realm=example-realm:add-identity-attribute(identity=alice, name=groups, value=["user"])
/subsystem=elytron/filesystem-realm=example-realm:set-password(identity=alice, clear={password=alice})
----

Now you can create a _http-authentication-factory_ that you'll use to actually protect your web applications using Undertow:
[source,options="nowrap"]
----
# Create a Http Authentication Factory
/subsystem=elytron/http-authentication-factory=example-http-authentication:add(security-domain=example-domain, http-server-mechanism-factory=global, mechanism-configurations=[{mechanism-name=FORM}]
----

=== Create a Application Security Domain in Undertow

[IMPORTANT]
If you already have a&nbsp;_application-security-domain_&nbsp;defined in Undertow subsystem and just want to use it to enable single sign-on to your applications, please skip this section.

In order to protect applications using the configuration defined in Elytron subsystem, you should create a application-security-domain definition in Undertow subsystem as follows:

----
/subsystem=undertow/application-security-domain=other:add(http-authentication-factory=example-http-authentication)
----

By default, if your application does not define any specific _security-domain_ in _jboss-web.xml_, the application server will choose one with a name *other*.

=== Create a Key Store

In order to create a _key-store_ in Elytron subsystem, first create a Java Key Store as follows:
[source,options="nowrap"]
----
keytool -genkeypair -alias localhost -keyalg RSA -keysize 1024 -validity 365 -keystore keystore.jks -dname "CN=localhost" -keypass secret -storepass secret
----

Once the _keystore.jks_ file is created, execute the following CLI commands to create a _key-store_ definition in Elytron:

[source,options="nowrap"]
----
/subsystem=elytron/key-store=example-keystore:add(path=keystore.jks, relative-to=jboss.server.config.dir, credential-reference={clear-text=secret}, type=JKS)
----


=== Enable Single Sign-On

Single Sign-On is enabled to a specific _application-security-domain_ definition in Undertow subsystem. It is important that the servers you will be using to deploy applications are using the same configuration.

To enable single-sign on, just change an existing application-security-domain in Undertow subsystem as follows:

[source,options="nowrap"]
----
/subsystem=undertow/application-security-domain=other/setting=single-sign-on:add(key-store=example-keystore, key-alias=localhost, domain=localhost, credential-reference={clear-text=secret})
----

After restarting the servers, users should be able to log in once and have access to any application using the same _application-security-domain_.

== Create Two Server Instances

All configuration you did so far should be reflected in _$JBOSS_HOME_/_standalone/standalone-ha.xml._ You can now create two distinct server configuration directories_:\_
[source,options="nowrap"]
----
cp -r standalone standalone-a
cp -r standalone standalone-b
----

And you can run the two instances using the command below:

----
$JBOSS_HOME/bin/standalone.sh -c standalone-ha.xml -Djboss.node.name=node-a -Djboss.socket.binding.port-offset=200 -Djboss.server.base.dir=$JBOSS_HOME/standalone-a
$JBOSS_HOME/bin/standalone.sh -c standalone-ha.xml -Djboss.node.name=node-b -Djboss.socket.binding.port-offset=300 -Djboss.server.base.dir=$JBOSS_HOME/standalone-b ----
----

== Deploy an Application

For the sake of simplicity, these are the minimum files you need in your application:

.WEB-INF/web.xml
[source,xml,options="nowrap"]
----
<web-app version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">

    <security-constraint>
        <display-name>SecurityConstraint</display-name>
        <web-resource-collection>
            <web-resource-name>All Resources</web-resource-name>
            <url-pattern>/*</url-pattern>
        </web-resource-collection>
        <auth-constraint>
            <role-name>user</role-name>
        </auth-constraint>
    </security-constraint>

    <login-config>
        <auth-method>FORM</auth-method>
        <form-login-config>
            <form-login-page>/login.html</form-login-page>
            <form-error-page>/login.html</form-error-page>
        </form-login-config>
    </login-config>

    <security-role>
        <role-name>user</role-name>
    </security-role>
</web-app>
----

.login.html
[source, html]
----
<html>
    <body>
        <form method="post" action="j_security_check">
            <input type="text" name="j_username">
            <input type="password" name="j_password">
            <input type="submit" value="Log In">
        </form>
    </body>
</html>
----

IMPORTANT: Make sure you have at least a welcome file (e.g.: index.html\|jsp).

--
Deploy your application into both server instances and try to log in using the user you created at the beginning of this document:

* Username: *alice*
* Password: *alice*
--
