我已经尝试在几个月前尝试安装Docker Cloud，但我将其删除。现在，我已经更新了杰西(Jessie(的debian stread，当我通过" apt-get update"更新时，我会发现此错误，并且不知道如何解决它。谁能提供帮助？谢谢！
sudo apt-get update
Get:1 http://debian.mirrors.ovh.net/debian stretch-updates InRelease
Ign:2 http://debian.mirrors.ovh.net/debian stretch InRelease
Get:3 http://repo.cloud.docker.com/ubuntu dockercloud InRelease [1,383 B]
Get:4 http://debian.mirrors.ovh.net/debian stretch Release
Hit:5 https://deb.nodesource.com/node_6.x jessie InRelease
Hit:6 https://apt.dockerproject.org/repo debian-stretch InRelease
Hit:7 http://security.debian.org stretch/updates InRelease
Ign:8 http://download.draios.com/stable/deb stable-amd64/ InRelease
Hit:9 http://download.draios.com/stable/deb stable-amd64/ Release
Ign:3 http://repo.cloud.docker.com/ubuntu dockercloud InRelease
Fetched 203 kB in 0s (247 kB/s)
Reading package lists... Done
W: GPG error: http://repo.cloud.docker.com/ubuntu dockercloud InRelease: The following signatures were invalid: 278FE7333CFF7F8B60B677E85DD27147EF170D1C
W: The repository 'http://repo.cloud.docker.com/ubuntu dockercloud InRelease' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: GPG error: http://repo.cloud.docker.com/ubuntu dockercloud InRelease: The following signatures were invalid: 278FE7333CFF7F8B60B677E85DD27147EF170D1C
W: The repository 'http://repo.cloud.docker.com/ubuntu dockercloud InRelease' is not signed.
实际上这是一个警告，而不是错误。似乎在您的sourceList中的某个地方(例如/etc/apt/sources.list(您仍然有一个docker存储库。
$ sudo grep -w "docker.com" /etc/apt/*.*
将显示Docker的URL在哪里。如果您不再需要它，请评论此行。
好吧，如果您仍然需要Docker，此链接可能会有所帮助。