Jib Build

Jib is a set of plugins for Maven and Gradle for building optimized OCI-compliant container images for Java applications without a Docker daemon.

Skaffold can help build artifacts using Jib; Jib builds the container images and then pushes them to the local Docker daemon or to remote registries as instructed by Skaffold.

Skaffold requires using Jib v1.4.0 or later.

Skaffold supports building with Jib

1. locally and
2. remotely on Google Cloud Build

Jib Maven and Gradle locally

Configuration

To use Jib, add a jib field to each artifact you specify in the artifacts part of the build section. context should be a path to your Maven or Gradle project.

The jib type offers the following options:

Skaffold’s jib support chooses the underlying builder (Maven or Gradle) based on the presence of standard build files in the artifact’s context directory:

• Maven: pom.xml, or .mvn directory.
• Gradle: build.gradle, gradle.properties, settings.gradle, or the Gradle wrapper script (gradlew, gradlew.bat, or gradlew.cmd).

Artifact Dependency

You can define dependency on other artifacts using the requires keyword. This can be useful to specify another artifact image as the fromImage.

build:
  artifacts:
  - image: image1 # jib artifact
    jib:
      fromImage: image2
    requires:
    - image: image2
  - image: image2 # base image artifact

Example

See the Skaffold-Jib demo project for an example.

Multi-Module Projects

Skaffold can be configured for multi-module projects too. A multi-module project has several modules (Maven terminology) or sub-projects (Gradle terminology) that each produce a separate container image.

Maven

To build a Maven multi-module project, first identify the sub-projects (also called modules in Maven) that should produce a container image. Then for each such sub-project:

• Create a Skaffold artifact in the skaffold.yaml.
• Set the artifact’s context field to the root project location.
• Add a jib element and set its project field to the sub-project’s :artifactId, groupId:artifactId, or the relative path to the sub-project within the project.

Gradle

To build a multi-module project with Gradle, first identify the sub-projects that should produce a container image. Then for each such sub-project:

• Create a Skaffold artifact in the skaffold.yaml.
• Set the artifact’s context field to the root project location.
• Add a jib element and set its project field to the sub-project’s name.

Remotely with Google Cloud Build

Skaffold can build artifacts using Jib remotely on Google Cloud Build.

Configuration

To configure, add googleCloudBuild to build section to skaffold.yaml. The following options can optionally be configured:

Example

Following configuration instructs skaffold to build gcr.io/k8s-skaffold/project1 with Google Cloud Build using Jib builder:

build:
  artifacts:
  - image: gcr.io/k8s-skaffold/project1
    jib: {}
  googleCloudBuild:
    projectId: YOUR-GCP-PROJECT

Advanced usage

Additional arguments

The jib build artifact supports an args field to provide additional arguments to the Maven or Gradle command-line. For example, a Gradle user may choose to use:

artifacts:
- image: jib-gradle-image
  jib:
    args: [--no-daemon]

Using the custom builder

Some users may have more complicated builds that may be better suited to using the custom builder. For example, the jib builder normally invokes the prepare-package goal rather than package as Jib packages the .class files rather than package in the jar. But some plugins require the package goal.

artifacts:
- image: jib-gradle-image
  custom:
    buildCommand: mvn -Dimage=$IMAGE package $(if [ $PUSH_IMAGE = true ]; then echo jib:build; else echo jib:dockerBuild; fi)
    dependencies:
      paths:
      - src/**