packer download url https://releases.hashicorp.com/packer/v1.4.1/packer_v1.4.1_linux_amd64.zip in Dockerfile is now wrong.
Right url: https://releases.hashicorp.com/packer/1.4.1/packer_1.4.1_linux_amd64.zip
need to add
jq -r -M '.current_version' | sed s/^v// )"; \
to fix