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. Please refer to the library’s documentation for more information on the supported Docker’s client API and Docker server version.

This plugin requires Gradle >= 2.5 to work properly.

Usage

To use the plugin, include in your build script:

buildscript {
    repositories {
        jcenter()
    }

    dependencies {
        classpath 'com.bmuschko:gradle-docker-plugin:X.Y.Z'
    }
}

Provided plugins

The JAR file comes with two plugins:

Plugin Id	Automatically 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'

If you would like to use this plugin from a build file which is not the main build file you must apply/use it like this:

build.gradle

apply from: 'gradle/docker.gradle'

gradle/docker.gradle

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.bmuschko:gradle-docker-plugin:X.Y.Z'
    }
}

// use fully qualified class name
apply plugin: com.bmuschko.gradle.docker.DockerRemoteApiPlugin

// import task classes
import com.bmuschko.gradle.docker.tasks.image.*

// use task classes

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
DockerCopyFileToContainer	Copies a path from the host into the container.
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.
DockerLogsContainer	Copies the container output to the Gradle process standard out/err.
DockerExecContainer	Executes a command within a running container.
DockerInspectExecContainer	Inspects task executed inside container with DockerExecContainer command.

Networks

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

Type	Description
DockerCreateNetwork	Creates a network.
DockerInspectNetwork	Returns low-level information on the network.
DockerRemoveNetwork	Removes the network.

Extension properties

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

Property name	Type	Default value	Description
url	String	see below	The server URL to connect to via Docker’s remote API.
certPath	File	null	The path to certificates for communicating with Docker over SSL.
apiVersion	String	null	The remote API version. For most cases this can be left null.

The default value is now generated based on a best guess attempt given the OperatingSystem and Environment:

Unix-based machine: unix:///var/run/docker.sock
Windows-based machine (and everything else): tcp://127.0.0.1:2375

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 = 'benjamin.muschko@gmail.com'
    }
}

Working with Google Cloud and using a key file

docker {
    registryCredentials {
        url = 'https://gcr.io'
        username = '_json_key'
        password = file('keyfile.json").text
    }
}

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.

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

On Unix the Docker daemon listens by default on unix:///var/run/docker.sock.

On Windows the Docker daemon listens by default on npipe:////./pipe/docker_engine though this is not currently supported. We instead fall back to tcp://127.0.0.1:2375.

Usage examples

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

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

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 "benjamin.muschko@gmail.com"'
}

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

Reactive-Streams

As needed, we will implement reactive methods as described in reactive-streams. We implement these here as optional closures for all tasks. Currently the only supported methods are onError, onNext, onComplete. Various examples on how to use these can be found in our reactive tests

onError

The onError closure is passed the exception that is thrown for YOU to handle. If you silently ignore we will not throw the exception behind the scenes. The below example is a common use-case that arises when someone wants to remove a container whether it exists or not but does not want to fail hard.

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

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

task removeContainer(type: DockerRemoveContainer) {
    targetContainerId { "container-that-does-not-exist" }
    onError { exception ->
        if (!exception.message.contains('No such container')) // ignore exception if container does not exist otherwise throw it
            throw exception
    }
}

onNext

The onNext closure is passed the next iterative response upon execution. For all other tasks we simply hand you back the object that is given to us by docker-java which is a pojo representation of the json handed back by docker. Thus, and much like the onException closure, all delegation is now in your control. Any properties/values expected to be set will not be done unless YOU do them.

Iterative tasks are things like DockerBuildImage, DockerLogsContainer, DockerListImages. These tasks have output which can be iterated over. The example below demonstrates how we iterate over each log message passing that to the closure for the user to work on.

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

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

task logContainer(type: DockerLogsContainer) {
    targetContainerId { "container-that-does-exist" }
    follow = true
    tailAll = true
    onNext { message ->
        logger.quiet message.toString() // each log message from the container will be passed as it's made available
    }
}

onComplete

The onComplete closure is not passed anything upon execution. It works in the same fashion that doLast does but is instead part of this task and thus executes before doLast does. This closure executes ONLY upon success. The below example demonstrates how this works.

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

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

task removeContainer(type: DockerRemoveContainer) {
    targetContainerId { "container-that-does-exist" }
    onComplete {
        println "Executes first"
    }
    doLast {
        println "Executes second"
    }
}

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 against the running container. At the end of this operation, the container is stopped.

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

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:latest'
}

task createMyAppContainer(type: DockerCreateContainer) {
    dependsOn buildMyAppImage
    targetImageId { buildMyAppImage.getImageId() }
    portBindings = ['8080:8080']
}

task startMyAppContainer(type: DockerStartContainer) {
    dependsOn createMyAppContainer
    targetContainerId { createMyAppContainer.getContainerId() }
}

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

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

Linking with other containers

In many situations your container does not start without dependencies like database. In that case you may wish using traditional linking:

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

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 createDBContainer(type: DockerCreateContainer) {
    targetImageId { 'postgres:latest' }
    containerName "docker_auto_${buildMyAppImage.buildTagName}"
}

task createMyAppContainer(type: DockerCreateContainer, dependsOn: [buildMyAppImage, createDBContainer]) {
    targetImageId { buildMyAppImage.getImageId() }
    portBindings = ['8080:8080']

    doFirst{ // doFirst required! #319
        links = [ "${createDBContainer.getContainerId()}:database" ] // `database` there will be host used by application to DB connect
    }

    // If you use Systemd in containers you should also add lines: (#320):
    binds = [ '/sys/fs/cgroup': '/sys/fs/cgroup' ]
    tty = true
}

task startMyAppContainer(type: DockerStartContainer, dependsOn: createMyAppContainer) {
    targetContainerId { createMyAppContainer.getContainerId() }
}

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.
exec	Closure	Create ENTRYPOINT using script from Application plugin	The ENTRYPOINT and/or CMD Dockerfile instructions
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 (Deprecated)
ports	Integer[]	[]	The Docker image exposed ports (if provided, this values will override port configuration property)
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 "benjamin.muschko@gmail.com"'
        ports = [9090, 5701]
        tag = 'jettyapp:1.115'
    }
}

exec property

The exec extension property accepts a Closure which delegates to the Dockerfile.CompositeExecInstruction subset of the Dockerfile task. It allows for specifying custom ENTRYPOINT or CMD commands at an appropriate location in the Dockerfile.

Usage example

docker {
    javaApplication {
        baseImage = 'dockerfile/java:openjdk-7-jre'
        maintainer = 'Benjamin Muschko "benjamin.muschko@gmail.com"'
        ports = [9090, 5701]
        tag = 'jettyapp:1.115'
        exec {
            defaultCommand 'server'
            entryPoint 'myApp/bin/containerLaunch.sh'
        }
    }
}

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	Sync	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 functional 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 "jon.doe@gmail.com"'
    }
}

Additional instructions in Dockerfile

You can add additional instructions to the dockerfile using dockerDistTar and Dockerfile task dsl:

dockerDistTar {
    instruction {'RUN ls -la'}
    environmentVariable('JAVA_OPTS', '-XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap')
}

docker {
    javaApplication {
    }
}

will result in

FROM java
MAINTAINER user
ADD javaapp-1.0.0-SNAPSHOT.tar /
ENTRYPOINT ["/javaapp-1.0.0-SNAPSHOT/bin/javaapp"]
EXPOSE 8080
RUN ls -la

Or you can use form

project.tasks.getByName("dockerDistTar").instructionsFromTemplate file("Dockerfile.tmpl")

FAQ

Executing the plugin’s test suite with custom configuration

The default setup can be configured with the help of the properties shown in the table below:

Description	System/Project/Environment variable	Default Value
Docker server URL	dockerServerUrl/dockerServerUrl/DOCKER_HOST	unix:///var/run/docker.sock
Docker cert path	dockerCertPath/dockerCertPath/DOCKER_CERT_PATH	null
Docker private registry URL	dockerPrivateRegistryUrl/dockerPrivateRegistryUrl/DOCKER_REGISTRY_HOST	http://localhost:5000

The following usage examples demonstrates running functional tests against the a docker instance:

./gradlew build functionalTest

OR

./gradlew build functionalTest -PdockerServerUrl=unix:///var/run/docker.sock

OR

./gradlew build functionalTest -DdockerServerUrl=unix:///var/run/docker.sock

OR

export DOCKER_HOST=unix:///var/run/docker.sock && ./gradlew build functionalTest

OR

./gradlew build functionalTest -PdockerServerUrl=http://192.168.59.103:2376

Using a Vagrant box to bootstrap Docker

Docker does not need to be installed on the local or another remote machine. This project provides a Vagrant image with the proper setup to bootstrap a Docker installation. The Vagrantfile can be found under the directory vagrant. To use the Vagrant box simply start it manually.

vagrant up

Automatically starts and stop Vagrant box for executing functional tests

An installation of VirtualBox and Vagrant is required. See the "Getting Started" guide for more information.

Alternatively, you can configure the project to bootstrap the Vagrant box as needed. Use the command line option -PbootstrapDocker=true for this purpose.

./gradlew functionalTest -PbootstrapDocker=true