Entry Dockerfile is a duplicate but no duplicate handling strategy has been set

[pstobiecki-ocado]

What happened?

With a Gradle configuration like this one:

docker {
    //  [...]

    dependsOn bootJar
    files bootJar.archivePath, fileTree('src/main/docker')
    dockerfile file('src/main/docker/Dockerfile')
    //  [...]
}

I'm getting the following error (with Gradle 7.3):

* What went wrong:
Execution failed for task ':edge:dockerPrepare'.
> Entry Dockerfile is a duplicate but no duplicate handling strategy has been set. Please refer to https://docs.gradle.org/7.3/dsl/org.gradle.api.tasks.Copy.html#org.gradle.api.tasks.Copy:duplicatesStrategy for details.

because the Dockerfile wants to be copied twice - once as part of the files config and then as itself. Providing a correct duplicatesStrategy for dockerPrepare could solve it, but it's impossible to do it without modifying the plugin code.

What did you want to happen?

It would be great if:

• the dockerPrepare task provided a duplicatesStrategy that allows such a build to pass, or
• it was possible to configure a duplicatesStrategy for this task per build.

I worked around it by changing the Gradle config like this:

files bootJar.archivePath, fileTree('src/main/docker').matching { exclude 'Dockerfile' }

but I'd much prefer for it to work out of the box.

[stuartraetaylor]

This still seems to be an issue.

I'm working around it in a multi-module project like this,

In the root build.gradle:

subprojects {
    pluginManager.withPlugin('com.palantir.docker') {
        dockerPrepare {
            // Workaround for https://github.com/palantir/gradle-docker/issues/518
            duplicatesStrategy = DuplicatesStrategy.INCLUDE
        }
    }
}

[lucasmfraser]

I don't think this is an issue with this plugin, but rather a caveat of Gradle 7. See these two threads:

• Gradle 7 requires duplicatesStrategy for "fake" duplicates - improve error message gradle/gradle#17236
• https://discuss.gradle.org/t/gradle-7-fail-for-duplicates-in-copy-specs-has-no-duplicates-in-project/39834/

[GeorgHoffmeyer]

I had a bit of the same issue. Problem is, that the dockerfile is in your src/main/docker folder. So it is first added with the files and than a second time with dockerfile

Solution 1:

Move Dockerfile to an other location than src/main/docker

Solution 2:

remove src/main/docker from files