Please refer to https://github.com/geosolutions-it/docker-geoserver
Base Docker image for GeoServer to be used as a template. The image built using Dockerfile contained in this repository is not meant to be used directly to run GeoServer but as a parent image for actual GeoServer images.
Most of the Dockerfile statements consist of ONBUILD actions that are triggered at children images build time.
Dockerfile accepts a few arguments at build time that define the base image to build from:
BASE_IMAGE_NAMEdefaults totomcatApache Tomcat official Docker ImageBASE_IMAGE_TAGdefaults tolatest
For instance
docker build --build-arg "BASE_IMAGE_TAG=7.0-jre8"
builds an image based on official Apache Tomcat at tag 7.0-jre8 ( Tomcat version 7.0 and Java JRE version 8 )
As stated above the image is not meant to run directly but as a template for other Docker images. Take a looks at this Dockerfile for an example of child image.
The actual usefulness of this Docker image becomes evident at children images build time where, thanks to the above mentioned ONBUILD statements, various aspects of final GeoServer container can be customized.
Take a look at this child image documentation or the corresponding Jenkins Job that builds it for more information, usage example and an actual GeoServer container ready to use.