deploy images automatically only when Dockerfile is updated?
Currently the images are pushed to Docker Hub on any commit to master. The only repository file that actually affects the build is Dockerfile. Any documentation update doesn't necessarily need to push new images. CI allows us to restrict the job only when Dockerfile is updated.
However, would also need a corresponding "force deploy" configuration to override this restriction and push a new build anyway. For example when Ubuntu updates its images, or when a new default branch build is made.