Converting POM using docker-maven-plugin to Gradle

These days I don’t get to use Gradle much, but I wanted to see how difficult it would be to convert a POM for building a Docker image into a Gradle build script.

It’s hard to tell exactly what plugin is recommended, but I guess it would be “com.palantir.docker”.

The POM for building the Docker image is part of a multiproject build including two other projects, each of which builds a WAR file. I found it pretty trivial to generate the Gradle build scripts for the other two projects, but the Docker one is a little harder. The examples on the “com.palantir.docker” plugin page don’t cover what I need to do.

In the existing POM, I specify the other two projects as dependencies using their GAV coordinates, including a JDBC driver jar. I use the Maven “copy-dependencies” task to get local copies of the dependencies that need to go into the image (stripping versions from the jar names), and I specify those artifacts in the configuration for the “docker-maven-plugin”.

The following is an excerpt of the current POM:
<dependencies> <dependency> <groupId>orderProcessingDashboard</groupId> <artifactId>ordersService</artifactId> <version>0.0.1-SNAPSHOT</version> <type>war</type> </dependency> <dependency> <groupId>orderProcessingDashboard</groupId> <artifactId>ordersGUI</artifactId> <version>0.0.1-SNAPSHOT</version> <type>war</type> </dependency> <dependency> <groupId>oracle</groupId> <artifactId>ojdbc6</artifactId> <version></version> </dependency> </dependencies> <repositories> <!-- Need this for the Oracle JDBC driver. --> <repository> ... repo info </repository> </repositories> <build> <plugins> <plugin> <groupId>com.spotify</groupId> <artifactId>docker-maven-plugin</artifactId> <executions> <execution> <id>build-image</id> <phase>package</phase> <goals> <goal>build</goal> </goals> </execution> </executions> <configuration> <dockerDirectory>${basedir}/src/docker</dockerDirectory> <imageName>ssorderprocessingdashboard</imageName> <resources> <resource> <directory>${}/dependencies</directory> <includes> <include>ordersService.war</include> <include>ordersGUI.war</include> <include>ojdbc6.jar</include> </includes> </resource> </resources> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-dependency-plugin</artifactId> <executions> <execution> <id>copy-dependencies</id> <phase>prepare-package</phase> <goals> <goal>copy-dependencies</goal> </goals> <configuration> <outputDirectory>${}/dependencies</outputDirectory> <excludeTransitive>true</excludeTransitive> <includeArtifactIds>ordersService,ordersGUI,ojdbc6</includeArtifactIds> <stripVersion>true</stripVersion> </configuration> </execution> </executions> </plugin> </plugins> </build>

So far, my build.gradle for this project is just the following, as I have no idea how to manage getting dependencies into the image (so I haven’t bothered to specify the dependencies yet):
`apply plugin: java

plugins {
id ‘com.palantir.docker’ version ‘’

docker {
name 'ssorderprocessingdashboard’
dockerfile ‘src/docker/Dockerfile’

With help from “Steve973” on IRC, I’ve been able to resolve part of this, which is how to gather the three required dependencies into a single place, so I can later refer to them somehow in the docker plugin.

I now have the following, which at least produces the artifacts I need to include in the image:
`dependencies {
runtime project(":ordersService")
runtime project(":ordersGUI")
runtime “oracle:ojdbc6:”

task copyDependencies << {
.each { artifact ->
project.copy {
from artifact.file
into "${buildDir}/dependencies"
rename { “${}.${artifact.extension}” }

build.dependsOn copyDependencies`

Now that I have them in a single place, I have to have a “docker” config block something like this:
docker { name 'ssorderprocessingdashboard' dockerfile 'src/docker/Dockerfile' files "ordersService.war", "ordersGUI.war", "ojbdc6.jar" }

But this isn’t quite right, because those three files are in “${buildDir}/dependencies”, so this fails to find them. I could add that prefix to all three of the files, but that’s messy. I thought I could do something like this:
files ["ordersService.war", "ordersGUI.war", "ojbdc6.jar"].each { "$buildDir/dependencies/" + it }

But this just fails with “Could not get unknown property ‘files’ for object of type com.palantir.gradle.docker.DockerExtension.”

I’ve concluded that I’m not going to get much response on issues with “com.palantir.docker”, so I’m going to start over using Ben Muschko’s “gradle-docker-plugin”, so I’m going to abandon this line of inquiry for now.