build.json

{
	"builders": [
		{
			"type": "docker",
			"image": "frolvlad/alpine-python3",
			"export_path": "image.tar"
		}
	],
	"provisioners": [
		{
			"type": "shell",
			"inline_shebang": "#!/bin/sh -xe",
			"inline": [
				"pip install ansible"
			]
		}
	]
}

output

docker output will be in this color.

==> docker: Creating a temporary directory for sharing data...
==> docker: Pulling Docker image: frolvlad/alpine-python3
    docker: Using default tag: latest
    docker: latest: Pulling from frolvlad/alpine-python3
    docker: Digest: sha256:ee5c821d27e92a15886f5ba565babfbe7f86c988b5dd50e47580eb2297bd1ddd
    docker: Status: Image is up to date for frolvlad/alpine-python3:latest
==> docker: Starting docker container...
    docker: Run command: docker run -v /Users/nm46057/.packer.d/tmp/packer-docker191164204:/packer-files -d -i -t frolvlad/alpine-python3 /bin/bash
==> docker: Error running container: Docker exited with a non-zero exit status.
==> docker: Stderr: docker: Error response from daemon: oci runtime error: exec: "/bin/bash": stat /bin/bash: no such file or directory.
==> docker:
Build 'docker' errored: Error running container: Docker exited with a non-zero exit status.
Stderr: docker: Error response from daemon: oci runtime error: exec: "/bin/bash": stat /bin/bash: no such file or directory.


==> Some builds didn't complete successfully and had errors:
--> docker: Error running container: Docker exited with a non-zero exit status.
Stderr: docker: Error response from daemon: oci runtime error: exec: "/bin/bash": stat /bin/bash: no such file or directory.


==> Builds finished but no artifacts were created.