Sorry 

Description of problem:
A properties file could be loaded with -P option when EAP is starting. 
Short value is loading well but long value is not loaded fully. From 53th character, it is not loaded. In other words, rest of the value after 53th string are ignored.

Version-Release number of selected component (if applicable):
EAP 6.0.1, 6.1Alpha

How reproducible:
This way is just for test.

Steps to Reproduce:
0. Set up postgresql datasource in standalone.xml

You can use my environment :
 <datasource jndi-name="java:jboss/PostgresDS" pool-name="PostgresDS" enabled="true">
                    <connection-url>jdbc:postgresql://10.64.165.175:5432/postgres</connection-url>
                    <driver>postgresql</driver>
                    <security>
                        <user-name>postgres</user-name>
                        <password>postgres</password>
                    </security>
                    <validation>
                        <valid-connection-checker class-name="org.jboss.jca.adapters.jdbc.extensions.postgres.PostgreSQLValidConnectionChecker"/>
                        <exception-sorter class-name="org.jboss.jca.adapters.jdbc.extensions.postgres.PostgreSQLExceptionSorter"/>
                    </validation>
                </datasource>
                <drivers>
                     <driver name="postgresql" module="org.postgresql">
                        <xa-datasource-class>org.postgresql.xa.PGXADataSource</xa-datasource-class>
                    </driver>
                </drivers>


(Note) You can test it with dstest.war 
      JNDI Name of Datasource: java:jboss/PostgresDS
      Table Name to Query (optional): jbtravel.user

1.Create db.properties
postgre.user=${VAULT::postgreDS_PW::password::ZGYwMmRmYTEtNzRjMS00M2JlLWFjNzEtZmIxMTU0ZTcxMjNlTElORV9CUkVBS3ZhdWx0}

2.Change standalon.xml 
<security>
   <user-name>${postgre.user:1111}</user-name>
   <password>postgres</password>
</security>
                   

3.test it with dstest.war for test.
 http://localhost:8080/dstest/
JNDI Name of Datasource: java:jboss/PostgresDS
Table Name to Query (optional): jbtravel.user
  

Actual results:
....
 Caused by: org.postgresql.util.PSQLException: FATAL: password authentication failed for user "${VAULT::postgreDB_PW::password::OGVjNWQ5N2QtODcwZC00MmE0LThlZW"
.....

Expected results:
Caused by: org.postgresql.util.PSQLException: FATAL: password authentication failed for user 
${VAULT::postgreDS_PW::password::ZGYwMmRmYTEtNzRjMS00M2JlLWFjNzEtZmIxMTU0ZTcxMjNlTElORV9CUkVBS3ZhdWx0}

Additional info:
Test Environment.
Postgresql ip :10.64.165.175:5432
ID : postgre
PW : postrgre

Created attachment 745040 [details]
Data Source Test War

I tested it again and found out the real property value is loaded properly.

However, if the value contains nested expression, EAP do not change it to plain text before passing it to database. Hence, EAP just pass nested expression "${VAULT::postgreDS_PW::password::ZGYwMmRmYTEtNzRjMS00M2JlLWFjNzEtZmIxMTU0ZTcxMjNlTElORV9CUkVBS3ZhdWx0}" as a real value.

Therefore, I should think this case title should be changed to "Do not support nested expression in Database password using -P option."

Thanks,
Jooho Lee, Jay.

I changed the issue title and made this a Feature Request. This is basically a request for a port of WFLY-117 to EAP 6.

WFLY-1177, not WFLY-117.

Sent pull request here:
https://github.com/jbossas/jboss-eap/pull/180

verified on EAP 6.2.0.ER1