This image provides a development image based around Alpine 3.3. This container is big on purpose. This is due to it having all the utilities required to compile either Java or C/C++ applications already installed within it.
It has autoconf, automake, GCC & Java 8 installed along with the following source control systems installed: cvs, git, mercurial, subversion
This is for development purposes only i.e. to allow you to build and package an application, library etc but not for deployment.
What you should do is use this image to perform the build, package them and submit to some repository. Then in a separate Dockerfile you build a fresh minimal image which then installs the result of the build into that container.
As they are configured the same, the configuration for this image is listed under the area51/ubuntu-dev image's instructions.
Installing additonal packages
The images have sudo installed and configured to allow the jenkins user to switch to root without a password. This was done to allow a build job to configure the container as part of the job it's working on.
So as part of your job you can install additional libraries required by your job simply with sudo apk add --update. Now this only affects this container and is lost when the container is destroyed - which is useful when running the container with the Cloud Bees plugin.
sudo apk add --update libarea51