gradle-docker

by palantir

palantir /gradle-docker

a Gradle plugin for orchestrating docker builds and pushes.

492 Stars 111 Forks Last release: 8 months ago (0.25.0) Apache License 2.0 218 Commits 46 Releases

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Docker Gradle Plugin

Build Status Gradle Plugins Release

This repository provides three Gradle plugins for working with Docker containers: -

com.palantir.docker
: add basic tasks for building and pushing docker images based on a simple configuration block that specifies the container name, the Dockerfile, task dependencies, and any additional file resources required for the Docker build. -
com.palantir.docker-compose
: adds a task for populating placeholders in a docker-compose template file with image versions resolved from dependencies. -
com.palantir.docker-run
: adds tasks for starting, stopping, statusing and cleaning up a named container based on a specified image

Docker Plugin

Apply the plugin using standard gradle convention:

plugins {
    id 'com.palantir.docker' version ''
}

Set the container name, and then optionally specify a Dockerfile, any task dependencies and file resources required for the Docker build. This plugin will automatically include outputs of task dependencies in the Docker build context.

Docker Configuration Parameters -

name
the name to use for this container, may include a tag -
tags
(deprecated) (optional) an argument list of tags to create; any tag in
name
will be stripped before applying a specific tag; defaults to the empty set -
tag
(optional) a tag to create with a specified task name -
dockerfile
(optional) the dockerfile to use for building the image; defaults to
project.file('Dockerfile')
and must be a file object -
files
(optional) an argument list of files to be included in the Docker build context, evaluated per
Project#files
. For example,
files tasks.distTar.outputs
adds the TAR/TGZ file produced by the
distTar
tasks, and
files tasks.distTar.outputs, 'my-file.txt'
adds the archive in addition to file
my-file.txt
from the project root directory. The specified files are collected in a Gradle CopySpec which may be copied
into
the Docker build context directory. The underlying CopySpec may also be used to copy entire directories into the build context. The following example adds the aforementioned archive and text file to the CopySpec, uses the CopySpec to add all files
from
src/myDir
into the CopySpec, then finally executes the copy into the directory
myDir
in docker build context.
gradle
docker {
    files tasks.distTar.outputs, 'my-file.txt'
    copySpec.from("src/myDir").into("myDir")
}
The final structure will be:
build/
  docker/
    myDir/
      my-file.txt
      // contents of task.distTar.outputs
      // files from src/myDir
-
buildArgs
(optional) an argument map of string to string which will set --build-arg arguments to the docker build command; defaults to empty, which results in no --build-arg parameters -
labels
(optional) a map of string to string which will set --label arguments to the docker build command; defaults to empty, which results in no labels applied. -
pull
(optional) a boolean argument which defines whether Docker should attempt to pull a newer version of the base image before building; defaults to
false
-
noCache
(optional) a boolean argument which defines whether Docker build should add the option --no-cache, so that it rebuilds the whole image from scratch; defaults to
false

To build a docker container, run the

docker
task. To push that container to a docker repository, run the
dockerPush
task.

Tag and Push tasks for each tag will be generated for each provided

tag
and
tags
entry.

Examples

Simplest configuration:

docker {
    name 'hub.docker.com/username/my-app:version'
}

Canonical configuration for building a Docker image from a distribution archive:

// Assumes that Gradle "distribution" plugin is applied
docker {
    name 'hub.docker.com/username/my-app:version'
    files tasks.distTar.outputs   // adds resulting *.tgz to the build context
}

Configuration specifying all parameters:

docker {
    name 'hub.docker.com/username/my-app:version'
    tags 'latest' // deprecated, use 'tag'
    tag 'myRegistry', 'my.registry.com/username/my-app:version'
    dockerfile file('Dockerfile')
    files tasks.distTar.outputs, 'file1.txt', 'file2.txt'
    buildArgs([BUILD_VERSION: 'version'])
    labels(['key': 'value'])
    pull true
    noCache true
}

Managing Docker image dependencies

The

com.palantir.docker
and
com.palantir.docker-compose
plugins provide functionality to declare and resolve version-aware dependencies between docker images. The primary use-case is to generate
docker-compose.yml
files whose image versions are mutually compatible and up-to-date in cases where multiple images depend on the existence of the same Dockerized service.

Specifying and publishing dependencies on Docker images

The

docker
plugin adds a
docker
Gradle component and a
docker
Gradle configuration that can be used to specify and publish dependencies on other Docker containers.

Example

plugins {
    id 'maven-publish'
    id 'com.palantir.docker'
}

...

dependencies { docker 'foogroup:barmodule:0.1.2' docker project(":someSubProject") }

publishing { publications { dockerPublication(MavenPublication) { from components.docker artifactId project.name + "-docker" } } }

The above configuration adds a Maven publication that specifies dependencies on

barmodule
and the
someSubProject
Gradle sub project. The resulting POM file has two
dependency
entries, one for each dependency. Each project can declare its dependencies on other docker images and publish an artifact advertising those dependencies.

Generating docker-compose.yml files from dependencies

The

com.palantir.docker-compose
plugin uses the transitive dependencies of the
docker
configuration to populate a
docker-compose.yml.template
file with the image versions specified by this project and all its transitive dependencies. The plugin uses standard Maven/Ivy machanism for declaring and resolving dependencies.

The

generateDockerCompose
task generates a
docker-compose.yml
file from a user-defined template by replacing each version variable by the concrete version declared by the transitive dependencies of the docker configuration. The task performs two operations: First, it generates a mapping
group:name --> version
from the dependencies of the
docker
configuration (see above). Second, it replaces all occurrences of version variables of the form
{{group:name}}
in the
docker-compose.yml.template
file by the resolved versions and writes the resulting file as
docker-compose.yml
.

The

docker-compose
plugin also provides a
dockerComposeUp
task that starts the docker images specified in the
dockerComposeFile
in detached mode. You can also use the
dockerComposeDown
task to stop the containers.

Example

Assume a

docker-compose.yml.template
as follows:
myservice:
  image: 'repository/myservice:latest'
otherservice:
  image: 'repository/otherservice:{{othergroup:otherservice}}'

build.gradle
declares a dependency on a docker image published as 'othergroup:otherservice' in version 0.1.2:
plugins {
    id 'com.palantir.docker-compose'
}

dependencies { docker 'othergroup:otherservice:0.1.2' }

The

generateDockerCompose
task creates a
docker-compose.yml
as follows:
myservice:
  image: 'repository/myservice:latest'
otherservice:
  image: 'repository/otherservice:0.1.2'

The

generateDockerCompose
task fails if the template file contains variables that cannot get resolved using the provided
docker
dependencies. Version conflicts between transitive dependencies of the same artifact are handled with the standard Gradle semantics: each artifact is resolved to the highest declared version.

Configuring file locations

The template and generated file locations are customizable through the

dockerCompose
extension:
dockerCompose {
    template 'my-template.yml'
    dockerComposeFile 'my-docker-compose.yml'
}

Docker Run Plugin

Apply the plugin using standard gradle convention:

plugins {
    id 'com.palantir.docker-run' version ''
}

Use the

dockerRun
configuration block to configure the name, image and optional command to execute for the
dockerRun
tasks:
dockerRun {
    name 'my-container'
    image 'busybox'
    volumes 'hostvolume': '/containervolume'
    ports '7080:5000'
    daemonize true
    env 'MYVAR1': 'MYVALUE1', 'MYVAR2': 'MYVALUE2'
    command 'sleep', '100'
    arguments '--hostname=custom', '-P'
}

Docker Run Configuration Parameters -

name
the name to use for this container, may include a tag. -
image
the name of the image to use. -
volumes
optional map of volumes to mount in the container. The key is the path to the host volume, resolved using
project.file()
. The value is the exposed container volume path. -
ports
optional mapping
local:container
of local port to container port. -
env
optional map of environment variables to supply to the running container. These must be exposed in the Dockerfile with
ENV
instructions. -
daemonize
defaults to true to daemonize the container after starting. However if your container runs a command and exits, you can set this to false. -
clean
(optional) a boolean argument which adds
--rm
to the
docker run
command to ensure that containers are cleaned up after running; defaults to
false
-
command
the command to run. -
arguments
additional arguments to be passed into the docker run command. Please see https://docs.docker.com/engine/reference/run/ for possible values.

Tasks

  • Docker
    • docker
      : build a docker image with the specified name and Dockerfile
    • dockerTag
      : tag the docker image with all specified tags
    • dockerTag
      : tag the docker image with
      
      
    • dockerPush
      : push the specified image to a docker repository
    • dockerPush
      : push the
       docker image to a docker repository
    • dockerTagsPush
      : push all tagged docker images to a docker repository
    • dockerPrepare
      : prepare to build a docker image by copying dependent task outputs, referenced files, and
      dockerfile
      into a temporary directory
    • dockerClean
      : remove temporary directory associated with the docker build
    • dockerfileZip
      : builds a ZIP file containing the configured Dockerfile
  • Docker Compose
    • generateDockerCompose
      : Populates a docker-compose file template with image versions declared by dependencies
    • dockerComposeUp
      : Brings up services defined in
      dockerComposeFile
      in detacted state
    • dockerComposeDown
      : Stops services defined in
      dockerComposeFile
  • Docker Run
    • dockerRun
      : run the specified image with the specified name
    • dockerStop
      : stop the running container
    • dockerRunStatus
      : indicate the run status of the container
    • dockerRemoveContainer
      : remove the container

License

This plugin is made available under the Apache 2.0 License.

Contributing

Contributions to this project must follow the contribution guide.

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