Programmers Quotes

Last week I gave a talk at the Agile 2009 conference about automating the deployment process with tools such as Maven, Nexus Cargo, Liquibase and Hudson. Here is a brief description of the talk:

Automating your build process with Continuous Integration is certainly a great idea, but why stop there? Why not go the whole nine yards and automate the deployment process as well? Staging and production deployments are typically more complicated and more involved than a simple development deployment, but doing them by hand can be time-consuming, tricky and error-prone. Indeed, turning your staging and production deployments into a one-click affair has a lot going for it.

This talk discusses a number of strategies for automating your deployment process, and shows how you can integrate CI tools like Hudson and Bamboo with other tools such as the popular JIRA issue tracking software for an (almost) seamless deployment experience. In particular, it will show in practical terms how to automate the deployment using Bamboo, JIRA and Nexus in a real-world multi-module Maven web application. The talk includes topics such as:

• How to integrate your build and deployment strategy with JIRA’s release management feature
• Subversion tagging strategies, and automatic Subversion tagging
• How to use a Maven repository manager to deploy and archive artifacts,
• How to use to automate the release process, and integrating Maven with JIRA and Bamboo
• How to automate deployment to different platforms (integration, staging, production, and so on)
• Handling automated redeployments and roll-backs
• How to set up automatic smoke tests
• How to handle security and traceability issues

You can view (and download) the slides here.

“Probably the best training course I’ve been on.”…”Not just how to write Java code but the ‘business end’ – how to build, test, deploy, manage and monitor”…”One of the best and most useful courses I have attended. And they didn’t even try to sell me anything!” - There are still some places for the courses in Wellington, Canberra, Brisbane and Sydney – Get up to speed with the latest and coolest in Java tools and best practices! Sign up on the 2009 season of the Java Power Tools Bootcamps.

If you have ever used Maven to any extent, you will probably know about the settings.xml file. The settings.xml file contains environment-specific details such as proxy configurations, repositories, server usernames and passwords, and so on.

An example of what typically might go into a settings.xml file is shown here:

<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0
                      http://maven.apache.org/xsd/settings-1.0.0.xsd">
  <localRepository>C:/maven/repository</localRepository>

  <proxies>
    <proxy>
      <id>localproxy</id>
      <active>true</active>
      <protocol>http</protocol>
      <host>proxy.acme.com</host>
      <port>8080</port>
      <username>scott</username>
      <password>t0ps3cr3t</password>
      <nonProxyHosts>*.acme.com</nonProxyHosts>
    </proxy>
  </proxies>
  ...
  <servers>
    <server>
      <id>dbserver</id>
      <username>scott</username>
      <password>tiger</password>
    </server>
  </servers>
  ...
</settings>

The localRepository element, for example, is very useful if you are using a corporate environment where your home directory is sent over the network each morning when you log on. Placing the local repository in a different directory on your local hard disk will, in this case, save a lot of band width.

You can also define repositories, mirrors, profiles and properties your the settings.xml. I don’t want to cover configuring these here, as it is fairly well documented elsewhere.

What is less well-known, or at least less frequently used, is the ability to use other data defined in the settings.xml file from within your pom.xml file. In fact, you can use any element of the settings.xml, though some are more useful than others.

One common, and easy, example is to use the localRepository variable. You might need to pass this variable to a script, or use it to refer to a particular JAR file in the repository (though there are usually more elegant solutions for that particular problem). You can use the localRepository property simply by referring to ${settings.localRepository}. For example, in the following code, we invoke an Ant script and pass it the local repository path in a property called “localRepository”:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-antrun-plugin</artifactId>
  <executions>
    <execution>
      <id>generate-stuff</id>
      <phase>pre-comile</phase>
      <goals>
        <goal>run</goal>
      </goals>
      <configuration>
        <tasks>
          <ant target="generate">
            <property name="localRepository"  value="${settings.localRepository}"/>
          </ant>
        </tasks>
      </configuration>
    </execution>
  </executions>
</plugin>

However, you can do much more interesting things, particularly when you also integrate Groovy into your build. For example, suppose that during the integration tests phase, we need to ensure that certain SQL scripts have been run on the database. We have a Groovy script called update-scripts.groovy that does just this, but it needs a username and password to be provided as command-line parameters. How could you run this script before the integration test phase, using the username and password that you defined in the settings.xml? Well, with a bit of Groovy magic, nothing is easier! The settings object is available to any Groovy scripting you integrate into your pom.xml, so you can simply use it like a normal object, as in the following example:

<plugin>
  <groupId>org.codehaus.groovy.maven</groupId>
  <artifactId>gmaven-plugin</artifactId>
  <version>1.0-rc-5</version>
  <executions>
    <execution>
      <id>process-db-scripts</id>
      <phase>pre-integration-test</phase>
      <goals>
        <goal>execute</goal>
      </goals>
      <configuration>
        <source>
        def server = settings.servers.find{ it.id.equals('dbserver') }
        """groovy update-scripts.groovy -Ddb.username=${server.username}
        -Ddb.password=${server.password}""".execute()
        </source>
      </configuration>
    </execution>
  </executions>
</plugin>

Easy as! In fact, once you know how to access not only the top-level variables, but also the collections within your settings.xml, the sky’s the limit! Just be sure to remember to make sure that your builds stay portable – for example, don’t define any properties in the settings.xml that don’t have sensible default values in the pom.xml file.

If you want to learn more cool ways to use Maven, check out the new online courses from Sonatype. Or, for a more global picture, come along to a Java Power Tools bootcamp session – there are workshops coming up soon in Canberra, Sydney, Brisbane and Wellington.

“Probably the best training course I’ve been on.”…”Not just how to write Java code but the ‘business end’ – how to build, test, deploy, manage and monitor”…”One of the best and most useful courses I have attended. And they didn’t even try to sell me anything!” - There are still some places for the courses in Wellington, Canberra, Brisbane and Sydney – Get up to speed with the latest and coolest in Java tools and best practices! Sign up on the 2009 season of the Java Power Tools Bootcamps.