Deploy an app to Heroku using Wildfly and Postgresql driver

Since a Postgres Database is the most simple persistent datastore at Heroku, I was trying to setup a jee application example using this SQL database. If you have already read some of my previous blogposts, I am using Buildpack API to deploy the application to a Dyno.

Since I already got an example working with Wildfly and Mysql, it was an easy step to conduct a buildpack to install the Postgresql driver into the Wildfly container. It’s now available at https://github.com/mwiede/heroku-buildpack-wildfly-postgresql.

I also provide an example of the application, which uses maven properties to extract the database url and credentials from system properties and use them in persistence.xml.

Here are the build and deploy steps to make it work (compare to https://github.com/mwiede/greeter#usage)

$ git clone https://github.com/mwiede/greeter.git
$ cd greeter
$ heroku create
$ heroku addons:create heroku-postgresql:hobby-dev
$ heroku buildpacks:clear
$ heroku buildpacks:add heroku/java
$ heroku buildpacks:add https://github.com/mwiede/heroku-buildpack-wildfly
$ heroku buildpacks:add https://github.com/mwiede/heroku-buildpack-wildfly-postgresql
$ git push heroku master
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encode special characters using maven-antrun-plugin

Recently I was deploying an java web application on heroku, but one of the fields, which were picked up from system properties to be used during the maven build to set the credentials of the datasource, contained a non escaped character, which brought the deployment to fail:

21:37:17,355 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-7) MSC000001: Failed to start service jboss.deployment.unit."ROOT.war".PARSE: org.jboss.msc.service.StartException in service jboss.deployment.unit."ROOT.war".PARSE: WFLYSRV0153: Failed to process phase PARSE of deployment "ROOT.war"

        at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:154)

        at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1948)

        at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1881)

        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)

        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)

        at java.lang.Thread.run(Thread.java:748)

Caused by: org.jboss.as.server.deployment.DeploymentUnitProcessingException: Unexpected character '<' (code 60) (expected a name start character)

 at [row,col {unknown-source}]: [25,26]

        at org.jboss.as.connector.deployers.ds.processors.DsXmlDeploymentParsingProcessor.deploy(DsXmlDeploymentParsingProcessor.java:105)

        at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:147)

        ... 5 more

Caused by: com.ctc.wstx.exc.WstxUnexpectedCharException: Unexpected character '<' (code 60) (expected a name start character)

 at [row,col {unknown-source}]: [25,26]

        at com.ctc.wstx.sr.StreamScanner.throwUnexpectedChar(StreamScanner.java:647)

        at com.ctc.wstx.sr.StreamScanner.parseFullName(StreamScanner.java:1933)

        at com.ctc.wstx.sr.StreamScanner.parseEntityName(StreamScanner.java:2057)

        at com.ctc.wstx.sr.StreamScanner.fullyResolveEntity(StreamScanner.java:1525)

        at com.ctc.wstx.sr.BasicStreamReader.nextFromTree(BasicStreamReader.java:2748)

        at com.ctc.wstx.sr.BasicStreamReader.next(BasicStreamReader.java:1073)

        at com.ctc.wstx.sr.BasicStreamReader.getElementText(BasicStreamReader.java:670)

        at org.jboss.jca.common.metadata.common.AbstractParser.rawElementText(AbstractParser.java:166)

        at org.jboss.jca.common.metadata.common.AbstractParser.elementAsString(AbstractParser.java:153)

        at org.jboss.jca.common.metadata.ds.DsParser.parseDataSource(DsParser.java:1149)

        at org.jboss.jca.common.metadata.ds.DsParser.parseDataSources(DsParser.java:177)

        at org.jboss.jca.common.metadata.ds.DsParser.parse(DsParser.java:120)

        at org.jboss.jca.common.metadata.ds.DsParser.parse(DsParser.java:79)

        at org.jboss.as.connector.deployers.ds.processors.DsXmlDeploymentParsingProcessor.deploy(DsXmlDeploymentParsingProcessor.java:90)

        ... 6 more

To come around this problem, we need to encode those characters as proper xml entities. So here is how I did this:

First, introduce the system property as maven property inside of the property section:

 <properties>
<db.url>${JDBC_DATABASE_URL}</db.url>
<db.user>${JDBC_DATABASE_USERNAME}</db.user>
<db.password>${JDBC_DATABASE_PASSWORD}</db.password>
</properties>

Second, define the maven-antrun-plugin as plugin to be executed during validate phase, the phase, before even resources are copied or filtered by maven. Important is that the flag exportAntProperties is set to true. I was not able to override an existing property, therefore I created new ones.

<plugin>
<artifactId>maven-antrun-plugin</artifactId>
<executions>
<execution>
<phase>validate</phase>
<configuration>
<exportAntProperties>true</exportAntProperties>
<target>
<script language="javascript">
<![CDATA[ 

if (!String.prototype.encodeHTML) {
String.prototype.encodeHTML = function () {
return this.replace(/&/g, '&amp;')
.replace(/</g, '&lt;')
.replace(/>/g, '&gt;')
.replace(/"/g, '&quot;')
.replace(/'/g, '&apos;');
};
}

project.setProperty("enc.db.url",project.getProperty("db.url").encodeHTML());
project.setProperty("enc.db.user",project.getProperty("db.user").encodeHTML());
project.setProperty("enc.db.password",project.getProperty("db.password").encodeHTML());

]]>
</script>
</target>
</configuration>
<goals>
<goal>run</goal>
</goals>
</execution>
</executions>
</plugin>

Third, use the properties in any resouce file while filtering:

<datasources xmlns="http://www.jboss.org/ironjacamar/schema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.jboss.org/ironjacamar/schema http://docs.jboss.org/ironjacamar/schema/datasources_1_0.xsd">
<!-- The datasource is bound into JNDI at this location. We reference
this in META-INF/persistence.xml -->
<datasource jndi-name="java:jboss/datasources/GreeterQuickstartDS"
pool-name="greeter-quickstart" enabled="true" use-java-context="true">
<connection-url>${enc.db.url}</connection-url>
<driver>postgresql</driver> 
<security>
<user-name>${enc.db.user}</user-name>
<password>${enc.db.password}</password>
</security>

</datasource>
</datasources>

See the complete code example at my github repo https://github.com/mwiede/greeter.

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