gecko-dev/taskcluster/docker/image_builder/policy.json

{
    "default": [{"type": "reject"}],
    "transports": {
        "docker-archive": {
            "": [{"type": "insecureAcceptAnything"}]
        },
        "dir": {
            "": [{"type": "insecureAcceptAnything"}]
        }
    }
}