Gradle Docker plugin

Gradle plugin for managing Docker images and containers using via its remote API. The heavy lifting of communicating with the Docker remote API is handled by the Docker Java library. Currently, version 1.2.0. Please refer to the library’s documentation for more information on the supported Docker’s client API and Docker server version.

Usage

To use the plugin, include in your build script:

buildscript {
    repositories {
        jcenter()
    }

    dependencies {
        classpath 'com.bmuschko:gradle-docker-plugin:2.3.1'
    }
}

Provided plugins

The JAR file comes with two plugins:

Plugin Identifier	Applies	Type	Description
com.bmuschko.docker-remote-api	-	DockerRemoteApiPlugin	Provides custom tasks for interacting with Docker via its remote API.
com.bmuschko.docker-java-application	com.bmuschko.docker-remote-api	DockerJavaApplicationPlugin	Creates and pushes a Docker image for a Java application.

Remote API plugin

The plugin com.bmuschko.docker-remote-api allows for interacting with Docker via its remote API. You can model any workflow imaginable by creating enhanced task of the custom task provided by the plugin. To use the plugin, include the following code snippet in your build script:

apply plugin: 'com.bmuschko.docker-remote-api'

The plugin automatically resolves the Docker Java library with the pre-configured version under the covers. The only configuration you will have to provide in your build script is the repository hosting the library and its transitive dependencies. One repository that hosts them all is Maven Central.

repositories {
    mavenCentral()
}

Custom task types

Misc

The plugin provides the following general-purpose custom task types:

Type	Description
DockerInfo	Displays system-wide information.
DockerVersion	Show the docker version information.

Images

The plugin provides the following custom task types for managing images:

Type	Description
Dockerfile	Creates a Dockerfile based on the provided instructions.
DockerBuildImage	Builds an image from a Dockerfile.
DockerCommitImage	Creates a new image from a container’s changes.
DockerInspectImage	Returns low-level information on the image.
DockerListImages	Lists images in registry.
DockerPullImage	Pulls an image from the registry.
DockerPushImage	Pushes an image to a registry.
DockerRemoveImage	Removes an image from the filesystem.
DockerTagImage	Tags an image in registry.

Containers

The plugin provides the following custom task types for managing containers:

Type	Description
DockerCopyFileFromContainer	Copies a path from the container as a tar file on to the host.
DockerCreateContainer	Creates a container.
DockerInspectContainer	Returns low-level information on the container.
DockerKillContainer	Kills the container for a given id.
DockerRemoveContainer	Removes the container for a given id from the filesystem.
DockerRestartContainer	Restarts the container for a given id.
DockerStartContainer	Starts the container for a given id.
DockerStopContainer	Stops the container for a given id.
DockerWaitContainer	Blocks until container for a given id stops, then returns the exit code.

Extension properties

The plugin defines the following extension properties in the docker closure:

Property name	Type	Default value	Description
`url`	String	http://localhost:2375	The server URL to connect to via Docker’s remote API.
`certPath`	File	null	The path to certificates for communicating with Docker over SSL.

Image pull or push operations against the public Docker Hub registry or a private registry may require authentication. You can provide those credentials in the registryCredentials closure:

Property name	Type	Default value	Description
`url`	String	https://index.docker.io/v1	The registry URL.
`username`	String	null	The registry username.
`password`	String	null	The registry password.
`email`	String	null	The registry email address.

Extension examples

Working with a TLS-enabled Docker instance

Starting with Docker version 1.3, TLS is enabled by default. Please consult the Docker documentation "Running Docker with https" to set up your certificate. The following example demonstrates how to configure the plugin to use those certificates. Additionally, this code snippet shows how to set the user credentials.

docker {
    url = 'https://192.168.59.103:2376'
    certPath = new File(System.properties['user.home'], '.boot2docker/certs/boot2docker-vm')

    registryCredentials {
        url = 'https://index.docker.io/v1'
        username = 'bmuschko'
        password = 'pwd'
        email = '[email protected]'
    }
}

Working with a Docker instance without TLS

The following example assumes that you disabled TLS on your Docker instance. You can do so by setting DOCKER_TLS=no in the file /var/lib/boot2docker/profile. Additionally, this code snippet shows how to set the user credentials.

docker {
    url = 'http://192.168.59.103:2375'
}

Usage examples

The following usage examples demonstrate code for common use cases. More scenarios can be found in the integration tests.

Creating a Dockerfile and building an image

A Dockerfile can be created by the Dockerfile custom tasks. The Dockerfile instructions need to be declare in the correct order.

import com.bmuschko.gradle.docker.tasks.image.Dockerfile
import com.bmuschko.gradle.docker.tasks.image.DockerBuildImage

task createDockerfile(type: Dockerfile) {
    destFile = project.file('build/mydockerfile/Dockerfile')
    from 'ubuntu:12.04'
    maintainer 'Benjamin Muschko "[email protected]"'
}

task buildImage(type: DockerBuildImage) {
    dependsOn createDockerfile
    inputDir = createDockerfile.destFile.parentFile
    tag = 'bmuschko/myimage'
}

Executing functional tests against a running container

The following example code demonstrates how to build a Docker image from a Dockerfile, starts up a container for this image and exercises functional tests agains the running container. At the end of this operation, the container is stopped.

import com.bmuschko.gradle.docker.tasks.container.*
import com.bmuschko.gradle.docker.tasks.image.*

task buildMyAppImage(type: DockerBuildImage) {
    inputDir = file('docker/myapp')
    tag = 'test/myapp'
}

task createMyAppContainer(type: DockerCreateContainer) {
    dependsOn buildMyAppImage
    targetImageId { buildMyAppImage.getImageId() }
}

task startMyAppContainer(type: DockerStartContainer) {
    dependsOn createMyAppContainer
    targetContainerId { createMyAppContainer.getContainerId() }
    portBindings = ['8080:8080']
}

task stopMyAppContainer(type: DockerStopContainer) {
    targetContainerId { createMyAppContainer.getContainerId() }
}

task functionalTestMyApp(type: Test) {
    dependsOn startMyAppContainer
    finalizedBy stopMyAppContainer
}

Java application plugin

The plugin com.bmuschko.docker-java-application is a highly opinonated plugin for projects applying the application plugin. Under the covers the plugin preconfigures tasks for creating and pushing Docker images for your Java application. The default configuration is tweakable via an exposed extension. To use the plugin, include the following code snippet in your build script:

apply plugin: 'com.bmuschko.docker-java-application'

Extension properties

The plugin defines the following extension properties in the javaApplication closure:

Property name	Type	Default value	Description
`baseImage`	String	java	The Docker base image used for Java application.
`maintainer`	String	Value of `user.home` system property	The name and email address of the image maintainer.
`port`	Integer	8080	The Docker image entry point port used for the Java application.
`tag`	String	<project.group>/<applicationName>:<project.version>	The tag used for the Docker image.

Usage example

docker {
    javaApplication {
        baseImage = 'dockerfile/java:openjdk-7-jre'
        maintainer = 'Benjamin Muschko "[email protected]"'
        port = 9090
        tag = 'jettyapp:1.115'
    }
}

Default tasks

The plugin provides a set of tasks for your project and preconfigures them with sensible defaults.

Task name	Depends On	Type	Description
`dockerCopyDistResources`	`distTar`	Copy	Copies the resource files (like the Java application’s TAR file) to a temporary directory for image creation.
`dockerDistTar`	`dockerCopyDistResources`	Dockerfile	Creates the Docker image for the Java application.
`dockerBuildImage`	`dockerDistTar`	DockerBuildImage	Builds the Docker image for the Java application.
`dockerPushImage`	`dockerBuildImage`	DockerPushImage	Pushes created Docker image to the repository.

Usage examples

The following usage examples demonstrate code for common use cases. More scenarios can be found in the integration tests.

apply plugin: 'java'
apply plugin: 'application'
apply plugin: 'com.bmuschko.docker-java-application'

version = '1.0'
sourceCompatibility = 1.7

repositories {
    mavenCentral()
}

dependencies {
    compile 'org.eclipse.jetty.aggregate:jetty-all:9.2.5.v20141112'
}

mainClassName = 'com.bmuschko.gradle.docker.application.JettyMain'

docker {
    javaApplication {
        maintainer = 'Jon Doe "[email protected]"'
    }
}

FAQ

Executing the plugin’s test suite with custom configuration

Integration and functional tests that are executed against a Docker instance assume a specific setup. This setup uses the Docker server URL http://localhost:2375 with TLS being disabled. The default setup can be configured with the help of system properties shown in the table below:

Description	System property	Default Value
Docker server URL	dockerServerUrl	http://localhost:2375
Docker cert path	dockerCertPath	null
Docker private registry URL	dockerPrivateRegistryUrl	http://localhost:5000

The following usage example demonstrates running the tests against a Docker instance using HTTPS:

./gradlew build -DdockerServerUrl=https://192.168.59.103:2376 -DdockerCertPath=/Users/ben/.boot2docker/certs/boot2docker-vm

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