作者：xcbeyond
博客：https://xcbeyond.cn/
在云时代，容器化已经成为一种事实，把软件产品打包、构建成 Docker 镜像是最基本、最关键的一步。在信创的大背景下，云环境中会存在 x86、arm 等不同的架构，所以在构建镜像时需要构建出多种架构的镜像，以适配不同架构的服务器。
在拉取 Docker 镜像时，会根据当前环境的架构自动拉取对应架构的镜像，如：在 x86 环境下拉取的镜像为 x86 架构的镜像，在 arm 环境下拉取的镜像为 arm 架构的镜像。（前提是，该镜像是多架构的镜像 ）
本文将针对基于 Docker Buildx 来构建多架构的镜像展开说明（一次构建多架构的镜像）。
1、buildx 安装
Docker Buildx 是一个 CLI 插件，它扩展了 Docker 命令，完全支持 Moby BuildKit 构建器工具包提供的功能。它提供与 docker build 相同的用户体验，具有许多新功能，例如创建作用域构建器实例和同时针对多个节点进行构建。
1. 下载 buildx 二进制文件。
在 Github Release 页面下载最新的 buildx 二进制文件。
根据您的操作系统选择对应的二进制文件。
2. buildx 复制到 Docker 对应目录。
重命名下载的 buildx 二进制文件，并将其复制到您操作系统对应的目录：
例如，我的 MacOS：
代码语言：javascript复制xcbeyond@xcbeyonddeMacBook-Pro ~ % mv ~/Downloads/buildx-v0.7.1.darwin-arm64 ~/.docker/cli-plugins/docker-buildx
xcbeyond@xcbeyonddeMacBook-Pro ~ % chmod x ~/.docker/cli-plugins/docker-buildx注意：需对 buildx 二进制文件赋予权限，执行 chmod x。
3. 检查 buildx。
执行 docker buildx version：
xcbeyond@xcbeyonddeMacBook-Pro ~ % docker buildx version
github.com/docker/buildx v0.7.1 05846896d149da05f3d6fd1e7770da187b52a2472、开启 binfmt_misc 来运行非本地架构的 Docker 镜像
如果您使用的是 Mac 或者 Windows 版本 Docker 桌面版，则可以跳过这个步骤，因为 binfmt_misc 默认开启。
如果使用的是其它平台，可使用 tonistiigi/binfmt 镜像进行安装：
代码语言：javascript复制 docker run --privileged --rm tonistiigi/binfmt --install all3、将默认 Docker 构建器切换为多架构构建器
默认情况下，Docker 会使用默认构建器，是不支持多架构构建。
为了构建多架构的镜像，需要创建新的支持多架构的构建器，需执行 docker buildx create --use：
xcbeyond@xcbeyonddeMacBook-Pro % docker buildx create --use --name mybuilder
mybuilder查看新的多架构构建器是否生效，需执行 docker buildx ls：
xcbeyond@xcbeyonddeMacBook-Pro % docker buildx ls
NAME/NODE DRIVER/ENDPOINT STATUS PLATFORMS
mybuilder * docker-container
mybuilder0 unix:///var/run/docker.sock inactive
desktop-linux docker
desktop-linux desktop-linux running linux/arm64, linux/amd64, linux/riscv64, linux/ppc64le, linux/s390x, linux/386, linux/arm/v7, linux/arm/v6
default docker
default default running linux/arm64, linux/amd64, linux/riscv64, linux/ppc64le, linux/s390x, linux/386, linux/arm/v7, linux/arm/v64、构建多架构镜像
1. 编写测试程序。
为方便测试，用 Golang 写了一个简单的程序，并输出当前程序运行环境的架构信息：
代码语言：javascript复制package main
import (
"fmt"
"runtime"
)
func main() {
fmt.Printf("the current platform architecture is %s.n", runtime.GOARCH)
}2. 编写 Dockerfile。
编写该程序的 Dockerfile：
代码语言：javascript复制FROM xcbeyond/go-builder:1.16
LABEL maintainer xcbeyond
WORKDIR /app
COPY multi-arch-test.go /app
RUN go build -o multi-arch-test /app/multi-arch-test.go
CMD ["./multi-arch-test"]3. 构建多架构镜像。
通过命令 docker buildx build -t <image-name> --platform=linux/arm64,linux/amd64 . --push，构建一个支持 arm64 和 amd64 架构的多架构镜像，并推送至 Docker Hub：
（参数 `--push` 会自动将镜像推送到 Docker Hub，本地并不会保留该镜像。如果不想推送，则可去掉该参数。）
代码语言：javascript复制xcbeyond@xcbeyonddeMacBook-Pro build-multi-platform-images-best-practices % docker buildx build -t xcbeyond/multi-arch-test --platform=linux/arm64,linux/amd64 . --push
[ ] Building 3105.4s (19/19) FINISHED
=> [internal] load build definition from Dockerfile 0.0s
=> => transferring dockerfile: 222B 0.0s
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [linux/amd64 internal] load metadata for docker.io/xcbeyond/go-builder:1.16 5.2s
=> [linux/arm64 internal] load metadata for docker.io/xcbeyond/go-builder:1.16 4.9s
=> [auth] xcbeyond/go-builder:pull token for registry-1.docker.io 0.0s
=> [internal] load build context 0.0s
=> => transferring context: 40B 0.0s
=> [linux/amd64 1/4] FROM docker.io/xcbeyond/go-builder:1.16@sha256:ace56967e44e98b1a8c286ad97717c878650d0312ac3e69767234f766601d6fc 2323.9s
=> => resolve docker.io/xcbeyond/go-builder:1.16@sha256:ace56967e44e98b1a8c286ad97717c878650d0312ac3e69767234f766601d6fc 0.0s
=> => sha256:6e1d20a8313edd44a36cb9198f4d11ac5eedb41d1faf5e8a33c5a0a5a25d2b92 85.80MB / 85.80MB 2318.7s
=> => sha256:6494e4811622b31c027ccac322ca463937fd805f569a93e6f15c01aade718793 54.57MB / 54.57MB 27.3s
=> => sha256:5b59121a0c3517cfd68aba8a3955cbb40ca12dd56db3317e3a17cf56131ca915 129.08MB / 129.08MB 77.1s
=> => sha256:cb5b7ae361722f070eca53f35823ed21baa85d61d5d95cd5a95ab53d740cdd56 10.87MB / 10.87MB 96.5s
=> => sha256:9b829c73b52b92b97d5c07a54fb0f3e921995a296c714b53a32ae67d19231fcd 5.15MB / 5.15MB 5.2s
=> => sha256:0e29546d541cdbd309281d21a73a9d1db78665c1b95b74f32b009e0b77a6e1e3 54.92MB / 54.92MB 61.0s
=> => extracting sha256:0e29546d541cdbd309281d21a73a9d1db78665c1b95b74f32b009e0b77a6e1e3 1.5s
=> => extracting sha256:9b829c73b52b92b97d5c07a54fb0f3e921995a296c714b53a32ae67d19231fcd 0.1s
=> => extracting sha256:cb5b7ae361722f070eca53f35823ed21baa85d61d5d95cd5a95ab53d740cdd56 0.3s
=> => extracting sha256:6494e4811622b31c027ccac322ca463937fd805f569a93e6f15c01aade718793 1.6s
=> => extracting sha256:6e1d20a8313edd44a36cb9198f4d11ac5eedb41d1faf5e8a33c5a0a5a25d2b92 1.9s
=> => extracting sha256:5b59121a0c3517cfd68aba8a3955cbb40ca12dd56db3317e3a17cf56131ca915 3.3s
=> => extracting sha256:2db41f0db9d9d9a1f49978ec31e8d187f491767e9b377f5ee121827c407e015e 0.0s
=> [linux/arm64 1/4] FROM docker.io/xcbeyond/go-builder:1.16@sha256:ace56967e44e98b1a8c286ad97717c878650d0312ac3e69767234f766601d6fc 2187.3s
=> => resolve docker.io/xcbeyond/go-builder:1.16@sha256:ace56967e44e98b1a8c286ad97717c878650d0312ac3e69767234f766601d6fc 0.0s
=> => sha256:221ff675cd357b3b345da24f781791fc9b91066d687f9e928993aab31618d13d 99.63MB / 99.63MB 54.3s
=> => sha256:627b3401fb617535edd16e96bd5941ecea7fe10ce6087bd47707602cfc396c2b 81.01MB / 81.01MB 472.1s
=> => sha256:841dd868500b6685b6cda93c97ea76e817b427d7a10bf73e9d03356fac199ffd 54.67MB / 54.67MB 2084.9s
=> => sha256:aa9c5b49b9db3dd2553e8ae6c2081b77274ec0a8b1f9903b0e5ac83900642098 10.66MB / 10.66MB 6.2s
=> => sha256:ac9d381bd1e98fa8759f80ff42db63c8fce4ac9407b2e7c8e0f031ed9f96432b 5.14MB / 5.14MB 6.8s
=> => sha256:94a23d3cb5be24659b25f17537307e7f568d665244f6a383c1c6e51e31080749 53.60MB / 53.60MB 22.7s
=> => extracting sha256:94a23d3cb5be24659b25f17537307e7f568d665244f6a383c1c6e51e31080749 1.5s
=> => extracting sha256:ac9d381bd1e98fa8759f80ff42db63c8fce4ac9407b2e7c8e0f031ed9f96432b 0.1s
=> => extracting sha256:aa9c5b49b9db3dd2553e8ae6c2081b77274ec0a8b1f9903b0e5ac83900642098 0.2s
=> => extracting sha256:841dd868500b6685b6cda93c97ea76e817b427d7a10bf73e9d03356fac199ffd 1.5s
=> => extracting sha256:627b3401fb617535edd16e96bd5941ecea7fe10ce6087bd47707602cfc396c2b 1.7s
=> => extracting sha256:221ff675cd357b3b345da24f781791fc9b91066d687f9e928993aab31618d13d 2.7s
=> => extracting sha256:10c716f05a00666c190fb40f99503dc83b2886de744ab9b3dc6c5d37d01f6e49 0.0s
=> [auth] xcbeyond/go-builder:pull token for registry-1.docker.io 0.0s
=> [linux/arm64 2/4] WORKDIR /app 0.1s
=> [linux/arm64 3/4] COPY multi-arch-test.go /app 0.0s
=> [linux/arm64 4/4] RUN go build -o multi-arch-test /app/multi-arch-test.go 0.3s
=> [linux/amd64 2/4] WORKDIR /app 0.2s
=> [linux/amd64 3/4] COPY multi-arch-test.go /app 0.0s
=> [linux/amd64 4/4] RUN go build -o multi-arch-test /app/multi-arch-test.go 1.5s
=> exporting to image 774.4s
=> => exporting layers 10.5s
=> => exporting manifest sha256:f38420339c9665b4f7d8b1e5edc66dc09e596ec7aa78113914b8a5b1b900e9e2 0.0s
=> => exporting config sha256:628f504898973d1d935ffd37993d1db5fdc4715c5d58467db2c6531d3d7d3181 0.0s
=> => exporting manifest sha256:a259302dca0d3f432d08f578e3243c5244bc50e54ea561c80dba03622897fcfd 0.0s
=> => exporting config sha256:47e7af533f821be5ba256919303e0de3b39990109a419a98dbfddc6c82086822 0.0s
=> => exporting manifest list sha256:8417543ebc47e6040a67a392d6ee9de05735ed464e48b22fcc3bdf66ce22224b 0.0s
=> => pushing layers 761.8s
=> => pushing manifest for docker.io/xcbeyond/multi-arch-test:latest@sha256:8417543ebc47e6040a67a392d6ee9de05735ed464e48b22fcc3bdf66ce22224b 2.0s
=> [auth] xcbeyond/multi-arch-test:pull,push token for registry-1.docker.io 0.0s
=> [auth] xcbeyond/multi-arch-test:pull,push token for registry-1.docker.io 0.0s
=> [auth] xcbeyond/multi-arch-test:pull,push token for registry-1.docker.io 0.0s5、测试多架构镜像
将构建的多架构镜像 xcbeyond/multi-arch-test:latest 进行测试，以确保能够正常运行，并使用对应架构镜像能够输出匹配的架构信息。
1. 查看每个架构镜像的信息。
执行命令 docker manifest inspect，可查看该镜像清单，并能得知该镜像对应架构的镜像 SHA 值：
xcbeyond@xcbeyonddeMacBook-Pro build-multi-platform-images-best-practices % docker manifest inspect xcbeyond/multi-arch-test:latest
{
"schemaVersion": 2,
"mediaType": "application/vnd.docker.distribution.manifest.list.v2 json",
"manifests": [
{
"mediaType": "application/vnd.docker.distribution.manifest.v2 json",
"size": 2419,
"digest": "sha256:f38420339c9665b4f7d8b1e5edc66dc09e596ec7aa78113914b8a5b1b900e9e2",
"platform": {
"architecture": "arm64",
"os": "linux"
}
},
{
"mediaType": "application/vnd.docker.distribution.manifest.v2 json",
"size": 2420,
"digest": "sha256:a259302dca0d3f432d08f578e3243c5244bc50e54ea561c80dba03622897fcfd",
"platform": {
"architecture": "amd64",
"os": "linux"
}
}
]
}也可以直接在 Docker Hub 上直接看到该镜像支持的多架构信息：
2. 根据不同架构镜像的 SHA 值，来逐一运行该镜像，并查看其输出结果。
分别执行 docker run --rm 命令：
arm 架构的镜像：
代码语言：javascript复制xcbeyond@xcbeyonddeMacBook-Pro build-multi-platform-images-best-practices % docker run --rm xcbeyond/multi-arch-test:latest@sha256:f38420339c9665b4f7d8b1e5edc66dc09e596ec7aa78113914b8a5b1b900e9e2
Unable to find image 'xcbeyond/multi-arch-test:latest@sha256:f38420339c9665b4f7d8b1e5edc66dc09e596ec7aa78113914b8a5b1b900e9e2' locally
docker.io/xcbeyond/multi-arch-test@sha256:f38420339c9665b4f7d8b1e5edc66dc09e596ec7aa78113914b8a5b1b900e9e2: Pulling from xcbeyond/multi-arch-test
94a23d3cb5be: Pull complete
ac9d381bd1e9: Pull complete
aa9c5b49b9db: Pull complete
841dd868500b: Pull complete
627b3401fb61: Pull complete
221ff675cd35: Pull complete
10c716f05a00: Pull complete
15bae122089f: Pull complete
d764b5be0a55: Pull complete
34bfa57028a2: Pull complete
Digest: sha256:f38420339c9665b4f7d8b1e5edc66dc09e596ec7aa78113914b8a5b1b900e9e2
Status: Downloaded newer image for xcbeyond/multi-arch-test@sha256:f38420339c9665b4f7d8b1e5edc66dc09e596ec7aa78113914b8a5b1b900e9e2
the current platform architecture is arm64.x86 架构的镜像：
代码语言：javascript复制xcbeyond@xcbeyonddeMacBook-Pro build-multi-platform-images-best-practices % docker run --rm xcbeyond/multi-arch-test:latest@sha256:a259302dca0d3f432d08f578e3243c5244bc50e54ea561c80dba03622897fcfd
Unable to find image 'xcbeyond/multi-arch-test:latest@sha256:a259302dca0d3f432d08f578e3243c5244bc50e54ea561c80dba03622897fcfd' locally
docker.io/xcbeyond/multi-arch-test@sha256:a259302dca0d3f432d08f578e3243c5244bc50e54ea561c80dba03622897fcfd: Pulling from xcbeyond/multi-arch-test
0e29546d541c: Pull complete
9b829c73b52b: Pull complete
cb5b7ae36172: Pull complete
6494e4811622: Pull complete
6e1d20a8313e: Pull complete
5b59121a0c35: Pull complete
2db41f0db9d9: Pull complete
f708bf6a9dc8: Pull complete
cb0d69b97354: Pull complete
a8f5aa83ecfb: Pull complete
Digest: sha256:a259302dca0d3f432d08f578e3243c5244bc50e54ea561c80dba03622897fcfd
Status: Downloaded newer image for xcbeyond/multi-arch-test@sha256:a259302dca0d3f432d08f578e3243c5244bc50e54ea561c80dba03622897fcfd
the current platform architecture is amd64.上面的输出结果，和我们的期望一致：多架构的镜像构建成功，并能在各自架构环境下运行。
6、总结
多架构镜像是基于 Docker Buildx 构建的，目前 buildx 还需额外安装，未来 buildx 很可能成为 docker build 命令的一部分，无需额外安装，毕竟多架构镜像已在各种场景中应用广泛起来了。
参考文章：
1. Docker Buildx
2. How to Build Multi-Architecture Docker Images with BuildX | Deploy containers to x86 and ARM!
