Jib — Build Java Container Images Without Docker

What it is

Jib is a container image builder created by Google that packages Java applications into optimized, layered OCI images directly from your Maven or Gradle build. No Dockerfile required. No Docker daemon required. Jib understands Java application structure and creates efficient image layers that separate dependencies from application code.

This tool is for Java developers and platform teams who want to containerize applications without learning Docker internals. It integrates into existing build tools so containerization is just another build step.

How it saves time or tokens

Jib eliminates the Dockerfile-write-build-push workflow. You add a plugin to your pom.xml or build.gradle, and mvn jib:build or gradle jib pushes a production-ready image. Layer optimization means only changed layers are rebuilt and pushed, saving CI time. The build is reproducible: same source always produces the same image.

How to use

1. Add the Jib plugin to your Maven or Gradle build file.
2. Configure the target image registry.
3. Run the build command.
4. The image is pushed directly to the registry.

<!-- Maven pom.xml -->
<plugin>
  <groupId>com.google.cloud.tools</groupId>
  <artifactId>jib-maven-plugin</artifactId>
  <version>3.4.0</version>
  <configuration>
    <to>
      <image>gcr.io/myproject/myapp</image>
    </to>
  </configuration>
</plugin>

# Build and push image (no Docker needed)
mvn compile jib:build

# Build to local Docker daemon
mvn compile jib:dockerBuild

# Build to a tar file
mvn compile jib:buildTar

Example

Gradle configuration:

plugins {
  id 'com.google.cloud.tools.jib' version '3.4.0'
}

jib {
  from {
    image = 'eclipse-temurin:21-jre'
  }
  to {
    image = 'gcr.io/myproject/myapp'
    tags = ['latest', project.version]
  }
  container {
    mainClass = 'com.myapp.Main'
    ports = ['8080']
    jvmFlags = ['-Xms256m', '-Xmx512m']
  }
}

Run gradle jib and the image is built and pushed.

Related on TokRepo

• DevOps tools — Container and deployment tools
• Automation tools — Build automation for CI/CD

Common pitfalls

• Jib pushes directly to a registry by default. Ensure your registry credentials are configured in Maven settings or Gradle properties.
• The base image must be compatible with your JDK version. Mismatched JDK versions cause runtime errors.
• Native dependencies or custom filesystem modifications need extra configuration since there is no Dockerfile to customize.
• Jib optimizes for standard Java applications. If your app has non-Java components (native binaries, config files in unusual locations), you need Jib's extra directories feature.
• Build reproducibility requires pinning the base image tag. Using latest creates non-reproducible builds.
• Review the official documentation before deploying to production to ensure compatibility with your specific environment and requirements.