How can I use Open Liberty dev mode with my Maven WAR project and include JavaScript and CSS files from outside my project (eg from my local machine)?

Question

I have some JavaScript and CSS files which are not part of my WAR module source repository. They are not packaged in a Maven dependency either. I separately extract them to a path on my local system.

How can I use include these resources in my Maven WAR application and still take advantage of liberty dev mode for rapid, iterative development?

score 0 · Accepted Answer · answered May 29 '22 at 20:12

To include web resources from locations other than the typical src/main/webapp directory, configure a property and the maven-war-plugin with the <webResources> parameter with something like this:

pom.xml

  ...
      <properties>
          <webResDir>/path/to/js-css</webResDir>
      <properties>
  ...
      <build>
        <plugins>
           <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.3.2</version>
                <configuration>
                    <webResources>
                        <resource>
                            <directory>${webResDir}</directory>
                       </resource>
                    </webResources>
                    <!-- I recommend this config which does a better job of removing any deleted/outdated resources, as of v3.3.2 -->
                    <outdatedCheckPath>/</outdatedCheckPath>
                </configuration>
            </plugin>

NOTES

While the basic idea still applies at earlier versions, you'll get a better experience with recommended minimum versions:

PREREQ MINIMUM VERSIONS

version 3.3.2 of maven-war-plugin (adds support for outdatedCheckPath syntax shown)
version 3.5.2 of liberty-maven-plugin (adds support for filtered web resources)

PLUGIN-LEVEL CONFIGURATION

Note too the maven-war-plugin configuration should be added at the plugin level for liberty dev mode to access it, rather than at the level of an execution defined under the maven-war-plugin.

PROPERTY OVERRIDE

As with Maven project properties in general, this can now be overridden:

on the command-line: mvn -DwebResDir=/some/path ... <goals, phases>
In settings.xml (especially useful if you have a host-specific location shared across multiple projects accessed from that system), e.g. see the Maven Settings documentation

REFERENCES

More examples here: https://maven.apache.org/plugins/maven-war-plugin/examples/adding-filtering-webresources.html