macOS环境下所有Ubuntu Docker镜像执行apt-get update时出现无效签名错误

我最近碰到了个挺棘手的问题：原本以为执行这条命令不会有任何问题：

docker run --rm ubuntu:focal apt-get update

但实际运行后却弹出了一堆GPG签名相关的错误，具体输出如下：

Get:1 http://ports.ubuntu.com/ubuntu-ports focal InRelease [265 kB]
Err:1 http://ports.ubuntu.com/ubuntu-ports focal InRelease
At least one invalid signature was encountered.
Get:2 http://ports.ubuntu.com/ubuntu-ports focal-updates InRelease [114 kB]
Err:2 http://ports.ubuntu.com/ubuntu-ports focal-updates InRelease
At least one invalid signature was encountered.
Get:3 http://ports.ubuntu.com/ubuntu-ports focal-backports InRelease [108 kB]
Err:3 http://ports.ubuntu.com/ubuntu-ports focal-backports InRelease
At least one invalid signature was encountered.
Get:4 http://ports.ubuntu.com/ubuntu-ports focal-security InRelease [114 kB]
Err:4 http://ports.ubuntu.com/ubuntu-ports focal-security InRelease
At least one invalid signature was encountered.
Reading package lists...
W: GPG error: http://ports.ubuntu.com/ubuntu-ports focal InRelease: At least one invalid signature was encountered.
E: The repository 'http://ports.ubuntu.com/ubuntu-ports focal InRelease' is not signed.
W: GPG error: http://ports.ubuntu.com/ubuntu-ports focal-updates InRelease: At least one invalid signature was encountered.
E: The repository 'http://ports.ubuntu.com/ubuntu-ports focal-updates InRelease' is not signed.
W: GPG error: http://ports.ubuntu.com/ubuntu-ports focal-backports InRelease: At least one invalid signature was encountered.
E: The repository 'http://ports.ubuntu.com/ubuntu-ports focal-backports InRelease' is not signed.
W: GPG error: http://ports.ubuntu.com/ubuntu-ports focal-security InRelease: At least one invalid signature was encountered.
E: The repository 'http://ports.ubuntu.com/ubuntu-ports focal-security InRelease' is not signed.

更奇怪的是，不管我换成哪个Ubuntu版本的标签，这个错误都会出现，完全没有例外。

我本地的Docker版本信息如下：

Client: Docker Engine - Community
Version:           23.0.5
API version:       1.42
Go version:        go1.20.3
Git commit:        bc4487a59e
Built:             Wed Apr 26 14:46:06 2023
OS/Arch:           darwin/arm64
Context:           default

Server: Docker Desktop 4.19.0 (106363)
Engine:
Version:          23.0.5
API version:      1.42 (minimum version 1.12)
Go version:       go1.19.8
Git commit:       94d3ad6
Built:            Wed Apr 26 16:17:14 2023
OS/Arch:          linux/arm64
Experimental:     false

containerd:
Version:          1.6.20
GitCommit:        2806fc1057397dbaeefbea0e4e17bddfbd388f38

runc:
Version:          1.1.5
GitCommit:        v1.1.5-0-gf19387a

docker-init:
Version:          0.19.0
GitCommit:        de40ad0

我本来以为这种问题应该有不少人碰到，但在Twitter上搜了一圈却没找到相关的报错报告。

后来我在一台Linux Docker主机上测试了同样的命令，结果完全正常，没有任何错误。这台Linux主机的Docker版本信息是：

Client: Docker Engine - Community
Version:           20.10.23
API version:       1.41
Go version:        go1.18.10
Git commit:        7155243
Built:             Thu Jan 19 17:45:08 2023
OS/Arch:           linux/amd64
Context:           default
Experimental:      true

Server: Docker Engine - Community
Engine:
Version:          20.10.23
API version:      1.41 (minimum version 1.12)
Go version:       go1.18.10
Git commit:       6051f14
Built:            Thu Jan 19 17:42:57 2023
OS/Arch:          linux/amd64
Experimental:     false

containerd:
Version:          1.6.16
GitCommit:        31aa4358a36870b21a992d3ad2bef29e1d693bec

runc:
Version:          1.1.4
GitCommit:        v1.1.4-0-g5fd4c4d

docker-init:
Version:          0.19.0
GitCommit:        de40ad0

备注：内容来源于stack exchange，提问作者jonseymour