Docker image rebuild
In this release we re-worked the docker image to be based on opendatacube/geobase, and to use multi-stage builds to create a slimmer docker image. The images should be compatible with previous builds, but there are some key differences:
- no index / setup scripts present in the image
- support datacube-ows-update instead of running the python script directly
- slimmer image (less Linux utils for increased security)
- run as non-root
- no startup script (improves compatibility with Kubernetes, by passing SIGTERM to gunicorn when pod is asked to shutdown)