docker output will be in this color.
==> docker: Creating a temporary directory for sharing data...
==> docker: Pulling Docker image: ubuntu
docker: Using default tag: latest
docker: latest: Pulling from library/ubuntu
docker: Digest: sha256:7a47ccc3bbe8a451b500d2b53104868b46d60ee8f5b35a24b41a86077c650210
docker: Status: Image is up to date for ubuntu:latest
==> docker: Starting docker container...
docker: Run command: docker run -v /root/.packer.d/tmp/packer-docker001065102:/packer-files -d -i -t ubuntu /bin/bash
docker: Container ID: 9dbe3834c612ce80bf670efd4383edfc0cfff9e8e84161f54df21fc497248eed
==> docker: Provisioning with shell script: /tmp/packer-shell985519329
==> docker: Killing the container: 9dbe3834c612ce80bf670efd4383edfc0cfff9e8e84161f54df21fc497248eed
Build 'docker' errored: Retryable error: Error uploading script: Upload failed with non-zero exit status: 1
==> Some builds didn't complete successfully and had errors:
--> docker: Retryable error: Error uploading script: Upload failed with non-zero exit status: 1
==> Builds finished but no artifacts were created.