Better image building

Description

Updates the current slim image generation dockerfile and script to allow for automatic worker name generation and custom version suffixes ("tags")

Changes

• The name now is a separate environment variable WORKERNAME instead of the hostname
• The all component for the build script is a synonym for no argument at all

Additions

• A second (optional) parameter that is part of the version suffix. An example: ./build-slim-image all experimental-metrics This builds and pushes both f00f/auta-core:1.2.0-experimental-metrics and f00f/auta-worker:1.2.0-experimental-metrics

Test and Review

To be filled in by the reviewers

• There are no unnecessary files present in the MR

• The continuous integration has no problems with the MR

• The MR is filled in as requested (including labels, milestones, and reviewers)

• The documentation is up-to-date