我正在尝试使用docker buildx构建多平台（amd64，arm64和armv7）映像。由于我使用的是运行Ubuntu 18.04的amd64计算机，因此我按照Docker website上的说明进行了操作，并通过以下方式安装了 qemu ：
sudo apt install qemu-user
但是，当我执行上一条命令时，出现一个奇怪的错误。更具体地说， binfmt-support 服务似乎存在问题。这是完整的日志：
Reading package lists... Done
Building dependency tree
Reading state information... Done
Starting pkgProblemResolver with broken count: 0
Starting 2 pkgProblemResolver with broken count: 0
Done
The following additional packages will be installed:
binfmt-support qemu-user-binfmt
The following NEW packages will be installed:
binfmt-support qemu-user qemu-user-binfmt
0 upgraded, 3 newly installed, 0 to remove and 1 not upgraded.
Need to get 0 B/7.409 kB of archives.
After this operation, 63,4 MB of additional disk space will be used.
Do you want to continue? [Y/n]
Selecting previously unselected package binfmt-support.
(Reading database ... 245278 files and directories currently installed.)
Preparing to unpack .../binfmt-support_2.1.8-2_amd64.deb ...
Unpacking binfmt-support (2.1.8-2) ...
Selecting previously unselected package qemu-user.
Preparing to unpack .../qemu-user_1%3a2.11+dfsg-1ubuntu7.21_amd64.deb ...
Unpacking qemu-user (1:2.11+dfsg-1ubuntu7.21) ...
Selecting previously unselected package qemu-user-binfmt.
Preparing to unpack .../qemu-user-binfmt_1%3a2.11+dfsg-1ubuntu7.21_amd64.deb ...
Unpacking qemu-user-binfmt (1:2.11+dfsg-1ubuntu7.21) ...
Setting up binfmt-support (2.1.8-2) ...
Job for binfmt-support.service failed because the control process exited with error code.
See "systemctl status binfmt-support.service" and "journalctl -xe" for details.
invoke-rc.d: initscript binfmt-support, action "start" failed.
● binfmt-support.service - Enable support for additional executable binary formats
Loaded: loaded (/lib/systemd/system/binfmt-support.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Wed 2020-02-05 17:20:29 CET; 4ms ago
Docs: man:update-binfmts(8)
Process: 7766 ExecStart=/usr/sbin/update-binfmts --enable (code=exited, status=2)
Main PID: 7766 (code=exited, status=2)
feb 05 17:20:29 XPS-15-9570 systemd[1]: Starting Enable support for additional executable binary formats...
feb 05 17:20:29 XPS-15-9570 update-binfmts[7766]: update-binfmts: warning: unable to close /proc/sys/fs/binfmt_misc/register: No such file or directory
feb 05 17:20:29 XPS-15-9570 update-binfmts[7766]: update-binfmts: exiting due to previous errors
feb 05 17:20:29 XPS-15-9570 systemd[1]: binfmt-support.service: Main process exited, code=exited, status=2/INVALIDARGUMENT
feb 05 17:20:29 XPS-15-9570 systemd[1]: binfmt-support.service: Failed with result 'exit-code'.
feb 05 17:20:29 XPS-15-9570 systemd[1]: Failed to start Enable support for additional executable binary formats.
Setting up qemu-user (1:2.11+dfsg-1ubuntu7.21) ...
Setting up qemu-user-binfmt (1:2.11+dfsg-1ubuntu7.21) ...
update-binfmts: warning: current package is qemu-user-binfmt, but binary format already installed by qemu-user-static
update-binfmts: exiting due to previous errors
dpkg: error processing package qemu-user-binfmt (--configure):
installed qemu-user-binfmt package post-installation script subprocess returned error exit status 2
Processing triggers for man-db (2.8.3-2ubuntu0.1) ...
Processing triggers for ureadahead (0.100.0-21) ...
Processing triggers for neon-settings (0.0+p18.04+git20191212.1343) ...
Processing triggers for systemd (237-3ubuntu10.33) ...
Errors were encountered while processing:
qemu-user-binfmt
E: Sub-process /usr/bin/dpkg returned an error code (1)
尽管如此，我还是尝试继续执行通常的过程，即：
docker buildx create --name mybuilder
docker buildx use mybuilder
docker buildx inspect --bootstrap
最后一条命令的输出为：
[+] Building 5.0s (1/1) FINISHED
=> [internal] booting buildkit 5.0s
=> => pulling image moby/buildkit:buildx-stable-1 4.3s
=> => creating container buildx_buildkit_mybuilder0 0.7s
Name: mybuilder
Driver: docker-container
Nodes:
Name: mybuilder0
Endpoint: unix:///var/run/docker.sock
Status: running
Platforms: linux/amd64, linux/386
如您所见，“ linux / amd64”和“ linux / 386”被列为唯一可用的平台，但是我需要为“ linux / arm64”和“ linux / arm / v7”平台构建映像也一样 数小时以来，我一直在寻找解决该问题的方法，尽管没有发现任何有效的方法
看起来我可以通过运行来解决部分问题：
sudo apt purge --auto-remove qemu-user qemu-user-binfmt binfmt-support
然后重新安装它们。实际上，再次运行以下命令：
sudo apt install qemu-user
完全没有错误：
Reading package lists... Done
Building dependency tree
Reading state information... Done
Starting pkgProblemResolver with broken count: 0
Starting 2 pkgProblemResolver with broken count: 0
Done
The following additional packages will be installed:
binfmt-support qemu-user-binfmt
The following NEW packages will be installed:
binfmt-support qemu-user qemu-user-binfmt
0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/7.409 kB of archives.
After this operation, 63,4 MB of additional disk space will be used.
Do you want to continue? [Y/n]
Selecting previously unselected package binfmt-support.
(Reading database ... 245437 files and directories currently installed.)
Preparing to unpack .../binfmt-support_2.1.8-2_amd64.deb ...
Unpacking binfmt-support (2.1.8-2) ...
Selecting previously unselected package qemu-user.
Preparing to unpack .../qemu-user_1%3a2.11+dfsg-1ubuntu7.21_amd64.deb ...
Unpacking qemu-user (1:2.11+dfsg-1ubuntu7.21) ...
Selecting previously unselected package qemu-user-binfmt.
Preparing to unpack .../qemu-user-binfmt_1%3a2.11+dfsg-1ubuntu7.21_amd64.deb ...
Unpacking qemu-user-binfmt (1:2.11+dfsg-1ubuntu7.21) ...
Setting up binfmt-support (2.1.8-2) ...
Created symlink /etc/systemd/system/multi-user.target.wants/binfmt-support.service → /lib/systemd/system/binfmt-support.service.
Setting up qemu-user (1:2.11+dfsg-1ubuntu7.21) ...
Setting up qemu-user-binfmt (1:2.11+dfsg-1ubuntu7.21) ...
Processing triggers for man-db (2.8.3-2ubuntu0.1) ...
Processing triggers for ureadahead (0.100.0-21) ...
Processing triggers for neon-settings (0.0+p18.04+git20191212.1343) ...
Processing triggers for systemd (237-3ubuntu10.38) ...
类似地，systemctl status binfmt-support.service的输出符合预期：
● binfmt-support.service - Enable support for additional executable binary formats
Loaded: loaded (/lib/systemd/system/binfmt-support.service; enabled; vendor preset: enabled)
Active: active (exited) since Mon 2020-02-10 11:42:23 CET; 1min 11s ago
Docs: man:update-binfmts(8)
Main PID: 7161 (code=exited, status=0/SUCCESS)
Tasks: 0 (limit: 4915)
CGroup: /system.slice/binfmt-support.service
feb 10 11:42:23 XPS-15-9570 systemd[1]: Starting Enable support for additional executable binary formats...
feb 10 11:42:23 XPS-15-9570 systemd[1]: Started Enable support for additional executable binary formats.
但是，部分问题仍然存在，因为运行这三个命令后的输出是：
docker buildx create --name mybuilder
docker buildx use mybuilder
docker buildx inspect --bootstrap
与以前相同，即：
[+] Building 2.6s (1/1) FINISHED
=> [internal] booting buildkit 2.6s
=> => pulling image moby/buildkit:buildx-stable-1 2.0s
=> => creating container buildx_buildkit_mybuilder0 0.6s
Name: mybuilder
Driver: docker-container
Nodes:
Name: mybuilder0
Endpoint: unix:///var/run/docker.sock
Status: running
Platforms: linux/amd64, linux/386
那是为什么？为什么显示linux/amd64和linux/386为唯一可用的平台？
docker context ls的输出是：
NAME DESCRIPTION DOCKER ENDPOINT KUBERNETES ENDPOINT ORCHESTRATOR
default * Current DOCKER_HOST based configuration unix:///var/run/docker.sock swarm
我也尝试在安装qemu之后重新启动docker，但是没有成功。另外，在docker buildx命令中指定目标平台：
docker buildx build -t <mytag> --platform linux/amd64,linux/arm64,linux/arm/v7 --load .
导致此错误：
[+] Building 0.6s (5/20)
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [internal] load build definition from Dockerfile 0.0s
=> => transferring dockerfile: 32B 0.0s
=> [linux/arm/v7 internal] load metadata for docker.io/alegeno92/opencv_python3:3.4.2 0.6s
=> CANCELED [linux/arm64 internal] load metadata for docker.io/alegeno92/opencv_python3:3.4.2 0.6s
=> CANCELED [linux/amd64 internal] load metadata for docker.io/alegeno92/opencv_python3:3.4.2 0.6s
failed to solve: rpc error: code = Unknown desc = failed to solve with frontend dockerfile.v0: failed to load LLB: runtime execution on platform linux/arm/v7 not supported
顺便说一句，我的内核版本是4.15.0-76-generic
答案 0 :(得分：21)
首先运行多体系结构容器
docker run --rm --privileged multiarch/qemu-user-static --reset -p yes
docker buildx rm builder
docker buildx create --name builder --driver docker-container --use
docker buildx inspect --bootstrap
您应该拥有备用架构。