To me quebrando aqui e não tem jeito que de jeito para conseguir fazer a conexão, o meu persistence.xml está como abaixo e a coisa não conecta por nada, o nome da base criada no openshift foi listacompras, segue codigo.
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
<persistence-unit name="projbetha" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<!-- Classes de persistencia -->
<class>entities.TipoLista</class>
<class>entities.Produto</class>
<class>entities.Lista</class>
<class>entities.ItemLista</class>
<exclude-unlisted-classes>true</exclude-unlisted-classes>
<properties>
<!-- Configurações para ter acesso ao banco de dados -->
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
<property name="hibernate.hbm2ddl.auto" value="update" />
<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" />
<property name="hibernate.connection.url" value="jdbc:mysql://${OPENSHIFT_MYSQL_DB_HOST}:${OPENSHIFT_MYSQL_DB_PORT}/${OPENSHIFT_APP_NAME}" />
<property name="hibernate.connection.username" value="${OPENSHIFT_MYSQL_DB_USERNAME}" />
<property name="hibernate.connection.password" value="${OPENSHIFT_MYSQL_DB_PASSWORD}" />
<!-- Seta o pool de conexões -->
<property name="c3p0.acquire_increment" value="1" />
<property name="c3p0.iddle_test_period" value="100" />
<property name="c3p0.max_size" value="100" />
<property name="c3p0.max_statements" value="0" />
<property name="c3p0.min_size" value="5" />
<property name="c3p0.timeout" value="100" />
<property name="c3p0.acquireRetryDelay" value="1000" />
<property name="c3p0.acquireRetryAttempts" value="60" />
<property name="c3p0.breakAfterAcquireFailure" value="false" />
</properties>
</persistence-unit>
</persistence>
O erro segue no link http://listacompras-danielmbiz.rhcloud.com/
