rusnyder/docker-dropwizard repository overview

⁠Docker Dropwizard

A Docker base image for building and running Dropwizard applications in Docker.

The aim of this project is to solve a specific problem:

• I've got a Dropwizard application I want to package up to run in Docker
• I'd like the image I produce to be configurable via "standard" Docker mechanisms (i.e. - build args and environment variables)
• I'd like to do so without adding any libraries to my runtime

The base image provides facilities for templating your Dropwizard config file without adding any runtime dependencies, since the config processing is handled out-of-process.

⁠Quickstart

The best way to use this project is as a base image for your Docker builds. This example is based off of an uberjar build for your Dropwizard project, but you can copy all of the dependencies directly to a container and set the classpath instead (see: Basic Classpath Integration Test⁠)

NOTE: This project is JUST a Docker base image and can thusly be used however you please; the Quickstart is just a complete (yet opinionated) example of how to effectively integrate the base image into your Dropwizard project

1. Add a dockerfile to your Dropwizard project

   # file: Dockerfile
   
   FROM rusnyder/docker-dropwizard:8-jre-alpine
   
   # Copy the DW uberjar, and set it to be run directly
   ARG JAR_FILE
   COPY target/${JAR_FILE} /${JAR_FILE}
   ENV DW_UBERJAR=/${JAR_FILE}
   
   # Copy the config template
   ARG CONFIG_TEMPLATE
   COPY ${CONFIG_TEMPLATE} /${CONFIG_TEMPLATE}
   ENV DW_CONFIG_TEMPLATE=/${CONFIG_TEMPLATE}
   
   # Run the "server" command (optional; 'server' is the default)
   CMD ["server"]
   

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2. Create a config template for your application (NOTE: docker-dropwizard uses Jinjava⁠ for templating, and feeds all environment variables in as Jinjava variables.)

   # file: src/docker/foobar-config.yml
   
   # A base config ships with docker-dropwizard that can be used to bootstrap
   #   common Dropwizard configs using exactly this line:
   {% include "base-dw-config.yml" %}
   
   # Add any additional config, optionally using Jinjava expressions
   foobar:
     someConfig: hello
     moreConfig: {{ SOME_MORE_CONFIG }}
   
   # Jinjava tags are also supported
   {% if SOME_ENABLE_BAR_BAZ_FLAG %}
   bar: baz
   {% endif %}
   

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3. Add a Dockerfile Maven⁠ plugin configuration to your build, setting the build args from the Dockerfile above. (NOTE: you can build the image using whatever plugins or tooling that you want, this is just an example)

   <!-- file: pom.xml -->
   <plugin>
     <groupId>com.spotify</groupId>
     <artifactId>dockerfile-maven-plugin</artifactId>
     <version>${dockerfile-maven-version}</version>
     <executions>
       <execution>
         <id>default</id>
         <goals>
           <goal>build</goal>
           <goal>push</goal>
         </goals>
       </execution>
     </executions>
     <configuration>
       <repository>rusnyder/foobar</repository>
       <tag>${project.version}</tag>
       <buildArgs>
         <JAR_FILE>${project.build.finalName}.jar</JAR_FILE>
         <CONFIG_TEMPLATE>src/docker/foobar-config.yml</CONFIG_TEMPLATE>
       </buildArgs>
     </configuration>
   </plugin>
   

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4. Build your project

   # The 'build' goal will create your docker image during the 'package' phase
   mvn clean package
   
   # The 'push' goal can push your image to your docker repository during the
   #   'deploy' phase, assuming you had a repo and credentials configured as-per
   #   the Dockerfile Maven documentation
   mvn deploy
   

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⁠Configuration Templating

The built image will (optionally) process a provided configuration template at docker run time to allow your containers to be portable and configurable.

Templates are rendered using Jinjava⁠ which provides a nearly-complete subset of the Jinja2⁠ templating language.

⁠Base Dropwizard Config

To save the hassle of having to define a template for all of the boilerplate Dropwizard configuration, a partial template is provided that you can include at the beginning of your config template:

{% include "base-dw-config.yml %}

This handles the majority of common Dropwizard configuration, and exposes many environment variables for container configuratioon:

Server

Logging

⁠Authors

• Russell Snyder [email protected]⁠