Dockerfile Maven
This is a Maven plugin and extension which help to seamlessly integrate Docker with Maven.
The design goals are:
- Don't try to do anything fancy.
Dockerfile
s are how you build Docker projects; that's what this plugin uses. They are mandatory. - Make the Docker build process integrate with the Maven build
process. If you bind the default phases, when you type
mvn package
, you get a Docker image. When you typemvn deploy
, your image gets pushed. - Make the goals remember what you are doing. You can type
mvn dockerfile:build
and latermvn dockerfile:tag
and latermvn dockerfile:push
without problems. This also eliminates the need for something likemvn dockerfile:build -DalsoPush
; instead you can just saymvn dockerfile:build dockerfile:push
. - Integrate with the Maven build reactor. You can depend on the Docker image of one project in another project, and Maven will build the projects in the correct order. This is useful when you want to run integration tests involving multiple services.
This project adheres to the Open Code of Conduct. By participating, you are expected to honor this code.
See the changelog for a list of releases
Set-up
This plugin requires Java 7 or later, and Apache Maven 3 or later. To run the integration tests or to use the plugin in practice, a working Docker set-up is needed.
Example
For more examples, see the integration test directory.
In particular, the advanced test showcases a
full service consisting of two micro-services that are integration
tested using helios-testing
.
This configures the actual plugin to build your image with mvn package
and push it with mvn deploy
. Of course you can also say
mvn dockerfile:build
explicitly.
<plugin>
<groupId>com.spotify</groupId>
<artifactId>dockerfile-maven-plugin</artifactId>
<version>${dockerfile-maven-version}</version>
<executions>
<execution>
<id>default</id>
<goals>
<goal>build</goal>
<goal>push</goal>
</goals>
</execution>
</executions>
<configuration>
<repository>spotify/foobar</repository>
<tag>${project.version}</tag>
<buildArgs>
<JAR_FILE>${project.build.finalName}.jar</JAR_FILE>
</buildArgs>
</configuration>
</plugin>
A corresponding Dockerfile
could look like:
FROM openjdk:8-jre
MAINTAINER David Flemström <dflemstr@spotify.com>
ENTRYPOINT ["/usr/bin/java", "-jar", "/usr/share/myservice/myservice.jar"]
# Add Maven dependencies (not shaded into the artifact; Docker-cached)
ADD target/lib /usr/share/myservice/lib
# Add the service itself
ARG JAR_FILE
ADD target/${JAR_FILE} /usr/share/myservice/myservice.jar
What does it give me?
There are many advantages to using this plugin for your builds.
Faster build times
This plugin lets you leverage Docker cache more consistently, vastly
speeding up your builds by letting you cache Maven dependencies in
your image. It also encourages avoiding the maven-shade-plugin
,
which also greatly speeds up builds.
Consistent build lifecycle
You no longer have to say something like:
mvn package
mvn dockerfile:build
mvn verify
mvn dockerfile:push
mvn deploy
Instead, it is simply enough to say:
mvn deploy
With the basic configuration, this will make sure that the image is built and pushed at the correct times.
Depend on Docker images of other services
You can depend on the Docker information of another project, because this plugin attaches project metadata when it builds Docker images. Simply add this information to any project:
<dependency>
<groupId>com.spotify</groupId>
<artifactId>foobar</artifactId>
<version>1.0-SNAPSHOT</version>
<type>docker-info</type>
</dependency>
Now, you can read information about the Docker image of the project that you depended on:
String imageName = getResource("META-INF/docker/com.spotify/foobar/image-name");
This is great for an integration test where you want the latest version of another project's Docker image.
Note that you have to register a Maven extension in your POM (or a
parent POM) in order for the docker-info
type to be supported:
<build>
<extensions>
<extension>
<groupId>com.spotify</groupId>
<artifactId>dockerfile-maven-extension</artifactId>
<version>${version}</version>
</extension>
</extensions>
</build>
Use other Docker tools that rely on Dockerfiles
Your project(s) look like so:
a/
Dockerfile
pom.xml
b/
Dockerfile
pom.xml
You can now use these projects with Fig or docker-compose or some
other system that works with Dockerfiles. For example, a
docker-compose.yml
might look like:
service-a:
build: a/
ports:
- '80'
service-b:
build: b/
links:
- service-a
Now, docker-compose up
and docker-compose build
will work as
expected.
Authentication and private Docker registry support
Since version 1.3.0, the plugin will automatically use any configuration in
your ~/.dockercfg
or ~/.docker/config.json
file when pulling, pushing, or
building images to private registries.
Additionally the plugin will enable support for Google Container Registry if it
is able to successfully load Google's "Application Default Credentials".
The plugin will also load Google credentials from the file pointed to by the
environment variable DOCKER_GOOGLE_CREDENTIALS
if it is defined. Since GCR
authentication requires retrieving short-lived access codes for the given
credentials, support for this registry is baked into the underlying
docker-client rather than having to first populate the docker config file
before running the plugin.
Authenticating with maven settings.xml
Since version 1.3.6, you can authenticate using your maven settings.xml instead of docker configuration. Just add configuration similar to:
<configuration>
<repository>docker-repo.example.com:8080/organization/image</repository>
<tag>latest</tag>
<useMavenSettingsForAuth>true</useMavenSettingsForAuth>
</configuration>
You can also use -Ddockerfile.useMavenSettingsForAuth=true
on the command line.
Then, in your maven settings file, add configuration for the server:
<servers>
<server>
<id>docker-repo.example.com:8080</id>
<username>me</username>
<password>mypassword</password>
</server>
</servers>
exactly as you would for any other server configuration.
Authenticating with maven pom.xml
Since version 1.3.XX, you can authenticate using config from the pom itself. Just add configuration similar to:
<plugin>
<groupId>com.spotify</groupId>
<artifactId>dockerfile-maven-plugin</artifactId>
<version>${version}</version>
<configuration>
<username>repoUserName</username>
<password>repoPassword</password>
<repository>${docker.image.prefix}/${project.artifactId}</repository>
<buildArgs>
<JAR_FILE>target/${project.build.finalName}.jar</JAR_FILE>
</buildArgs>
</configuration>
</plugin>
or simpler,
<plugin>
<groupId>com.spotify</groupId>
<artifactId>dockerfile-maven-plugin</artifactId>
<version>${version}</version>
<configuration>
<repository>${docker.image.prefix}/${project.artifactId}</repository>
<buildArgs>
<JAR_FILE>target/${project.build.finalName}.jar</JAR_FILE>
</buildArgs>
</configuration>
</plugin>
with this command line call
mvn goal -Ddockerfile.username=... -Ddockerfile.password=...
Skip Docker Goals Bound to Maven Phases
You can pass options to maven to disable the docker goals.
Maven Option | What Does that thing Do? |
---|---|
dockerfile.skip | Disables the entire dockerfile plugin; all goals become no-ops. |
dockerfile.build.skip | Disables the build goal; it becomes a no-op. |
dockerfile.tag.skip | Disables the tag goal; it becomes a no-op. |
dockerfile.push.skip | Disables the push goal; it becomes a no-op. |
For example to skip the entire dockerfile plugin:
mvn clean package -Ddockerfile.skip