【Docker】docker使用buildx同时构建多平台镜像

在使用docker build的时候，有的时候需要构建非当前平台版本的镜像，比如我在arm的机器上构建x86的镜像，反之亦然。这时候传统的docker build命令就行不通了，需要使用buildx来支持构建多平台镜像。

1	docker buildx build --platform linux/arm64,linux/amd64 -t ubuntu-x11:18.04 .

执行这个命令的时候，可能会遇到如下输出（mac下的docker desktop）

❯ docker buildx build --platform linux/arm64,linux/amd64 -t ubuntu-x11:18.04 .
[+] Building 0.0s (0/0)                                                               docker:desktop-linux
ERROR: Multi-platform build is not supported for the docker driver.
Switch to a different driver, or turn on the containerd image store, and try again.
Learn more at https://docs.docker.com/go/build-multi-platform/

这个ERROR的含义是当前的docker builder不支持多平台镜像build，需要切换builder。

# 先创建一个新的 buildx builder，并指定 docker-container 作为驱动
docker buildx create --name mybuilder --use --driver docker-container
# 确保 buildx 处于正确状态
docker buildx ls
# 随后就可以正常 build 了
docker buildx build --platform linux/arm64,linux/amd64 -t ubuntu-x11:18.04 --push .

这里必须要给命令加上一个--push选项将镜像push到远端仓库或者本地仓库，因为buildx没有办法直接把镜像写入images中。如果需要push到dockerhub则需要先执行docker login登录一下。

1
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WARNING: No output specified with docker-container driver. Build result will only remain in the build cache. To push result image into registry use --push or to load image into docker use --load
dockerfile:1

不过，后续我执行命令的时候一直因为dockerhub没有办法连上导致拉不下原始的镜像，麻了……

❯ docker buildx build --platform linux/amd64 -t musnows/ubuntu-x11:18.04  --push  . 

[+] Building 30.8s (3/3) FINISHED                                               docker-container:mybuilder
 => [internal] load build definition from dockerfile                                                  0.0s
 => => transferring dockerfile: 1.88kB                                                                0.0s
 => ERROR [internal] load metadata for docker.io/musnows/ubuntu:18.04                                30.7s
 => [auth] musnows/ubuntu:pull token for registry-1.docker.io                                         0.0s
------
 > [internal] load metadata for docker.io/musnows/ubuntu:18.04:
------
dockerfile:2
--------------------
   1 |     # this images is build from dockerfile.base
   2 | >>> FROM musnows/ubuntu:18.04
   3 |     
   4 |     ARG DEBIAN_FRONTEND=noninteractive
--------------------
ERROR: failed to solve: musnows/ubuntu:18.04: failed to resolve source metadata for docker.io/musnows/ubuntu:18.04: failed to authorize: failed to fetch oauth token: Post "https://auth.docker.io/token": dial tcp [2a03:2880:f10d:183:face:b00c:0:25de]:443: i/o timeout