构建多架构镜像的最佳实践
作者：xcbeyond
- 2022 年 1 月 22 日
本文字数：9832 字
阅读完需：约 32 分钟
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：
xcbeyond@xcbeyonddeMacBook-Pro ~ % mv ~/Downloads/buildx-v0.7.1.darwin-arm64 ~/.docker/cli-plugins/docker-buildxxcbeyond@xcbeyonddeMacBook-Pro ~ % chmod +x ~/.docker/cli-plugins/docker-buildx复制代码
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 05846896d149da05f3d6fd1e7770da187b52a247复制代码
2、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：
docker run --privileged --rm tonistiigi/binfmt --install all复制代码
3、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复制代码
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 lsNAME/NODE DRIVER/ENDPOINT STATUS PLATFORMSmybuilder * 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/v6default docker default default running linux/arm64, linux/amd64, linux/riscv64, linux/ppc64le, linux/s390x, linux/386, linux/arm/v7, linux/arm/v6复制代码
4、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：
package main
import ( "fmt" "runtime")
func main() { fmt.Printf("the current platform architecture is %s.\n", runtime.GOARCH)}复制代码
2. 编写 Dockerfile。
编写该程序的 Dockerfile：
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"]复制代码
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。）
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 0.0s复制代码
5、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" } } ] }复制代码
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：
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.复制代码
x86 架构的镜像：
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.
复制代码
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：
2. How to Build Multi-Architecture Docker Images with BuildX | Deploy containers to x86 and ARM!
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版权声明: 本文为 InfoQ 作者【xcbeyond】的原创文章。
原文链接:【http://xie.infoq.cn/article/1b51d198417f80f9adc8dd691】。文章转载请联系作者。
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