Add gradle-oci to implementations.md

[SgtSilvio]

As the author of the Gradle OCI plugin I want to ask if it can be included in the list of implementations.

It is a Gradle plugin to ease using and producing (multi-arch) OCI images without requiring external tools.

The plugin allows:

• Building OCI images according to the OCI Image Format Specification
• Pulling and pushing images from/to OCI registries according to the OCI Distribution Specification

Please let me know if any additional information is required.

[sudo-bmitch]

Hi @SgtSilvio, I'm not a Java / Gradle / Kotlin dev, so this is out of my expertise. But that's not really needed to approve this. Do you have an example image created by this project on a public repo that we could review?

[SgtSilvio]

Thanks for your answer.
The hivemq/hivemq-swarm is a public image that has been built with gralde-oci since December. (example tag: 4.23.0).
The project source is private, but I can share the image definition below.
In short,

• it has distroless/java11-debian11:latest as parent image and
• adds 3 layers (called "libs", "jar" and "resources")
• for the platforms linux/amd64 and linux/arm64/v8

Full Image Definition

oci {
    imageDefinitions.register("main") {
        allPlatforms {
            parentImages {
                add("distroless:java11-debian11:latest") { isChanging = true }
            }
            config {
                entryPoint.add("java")
                entryPoint.addAll(application.applicationDefaultJvmArgs)
                entryPoint.addAll(
                    "-XX:+UnlockExperimentalVMOptions",
                    "-XX:+UseG1GC",
                    "-XX:InitialRAMPercentage=60",
                    "-XX:MaxRAMPercentage=70",
                    "-XX:MinRAMPercentage=40",
                    "-Dswarm.home=/",
                    "-cp",
                    "/app/classpath/*:/app/libs/*",
                )
                entryPoint.add(application.mainClass)
                environment.put("LOG_LEVEL", "INFO")
            }
            layers {
                layer("libs") {
                    contents {
                        from(configurations.runtimeClasspath)
                        into("app/libs")
                    }
                }
                layer("jar") {
                    contents {
                        from(proguardJar.flatMap { it.inputOutputGroups[0].outputs[0].archiveFile })
                        into("app/classpath")
                        rename(".*", "${project.name}-${project.version}.jar")
                    }
                }
                layer("resources") {
                    contents {
                        from("src/distribution")
                        from("src/main/resources/logback.xml") { into("config") }
                        from(standardExtensions) { into("extensions") }
                        filter.exclude("config/config.xml", "scenario/scenario.xml", "**/Readme.md")
                    }
                }
            }
        }
        specificPlatform(platform("linux", "amd64"))
        specificPlatform(platform("linux", "arm64", "v8"))
    }
}

[sudo-bmitch]

LGTM