一次构建多平台docker镜像
Linux 平台信息
下面简单列举一些
- linux/amd64 目前最主流的 X86_64
- linux/arm64
- linux/arm
- linux/arm/v6
- linux/arm/v7
问题
Linux 有很多平台，有没有办法只构建一次就能构建出所有的平台镜像？答案是有的，下面介绍的工具刚好能解决这个问题。
Docker Buildx
Docker Buildx 是一个CLI插件，扩展了docker命令，并完全支持 Moby BuildKit 构建器工具包提供的功能. 它提供了与 docker build 相同的用户体验，并具有许多新功能，例如：创建范围内的构建器实例和同时针对多个节点进行构建。
安装
- 直接安装
Docker v19.03版本，该版本已包含Docker Buildx组件，因为目前还是实验功能，默认没有开启。通过设置DOCKER_CLI_EXPERIMENTAL环境变量来开启。
$ export DOCKER_CLI_EXPERIMENTAL=enabled
切换到 docker buildx 构建器
# 创建 mybuilder 构建器
$ docker buildx create --use --name mybuilder
# 验证构建器是否生效
$ docker buildx ls
NAME/NODE DRIVER/ENDPOINT STATUS PLATFORMS
mybuilder * docker-container
mybuilder0 unix:///var/run/docker.sock running linux/amd64, linux/386
default docker
default default running linux/amd64, linux/386
构建多平台镜像
- 创建
Dockerfile
# 使用node镜像，打印一个当前运行平台
$ vim Dockerfile
FROM --platform=$BUILDPLATFORM node:alpine AS build
ARG TARGETPLATFORM
ARG BUILDPLATFORM
RUN echo "I am running on $BUILDPLATFORM, building for $TARGETPLATFORM" > /log
FROM alpine
COPY --from=build /log /log
CMD ["cat", "/log"]
- 构成 linux/arm, linux/arm64, linux/amd64 镜像
# 构建前需要配置好推送的镜像仓库，目前构建的镜像不会保存在本地。这里我使用 dockerhub 镜像仓库
$ docker buildx build -t yangpeng2468/test --platform=linux/arm,linux/arm64,linux/amd64 . --push
[+] Building 15.8s (17/17) FINISHED
=> [internal] load build definition from Dockerfile 0.0s
=> => transferring dockerfile: 32B 0.0s
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [linux/amd64 internal] load metadata for docker.io/library/alpine:latest 0.9s
=> [linux/arm/v7 internal] load metadata for docker.io/library/alpine:latest 2.1s
=> [linux/arm64 internal] load metadata for docker.io/library/alpine:latest 2.1s
=> [linux/amd64 internal] load metadata for docker.io/library/node:alpine 2.4s
=> [linux/amd64 build 1/2] FROM docker.io/library/node:alpine@sha256:bdf054f006078036f72de45553f3b11176c1c00d5451d8fc2af206636eb54d70 0.0s
=> => resolve docker.io/library/node:alpine@sha256:bdf054f006078036f72de45553f3b11176c1c00d5451d8fc2af206636eb54d70 0.0s
=> [linux/arm64 stage-1 1/2] FROM docker.io/library/alpine@sha256:c19173c5ada610a5989151111163d28a67368362762534d8a8121ce95cf2bd5a 0.0s
=> CACHED [linux/amd64 build 2/2] RUN echo "I am running on linux/amd64, building for linux/arm64" > /log 0.0s
=> CACHED [linux/arm64 stage-1 2/2] COPY --from=build /log /log 0.0s
=> [linux/arm/v7 stage-1 1/2] FROM docker.io/library/alpine@sha256:c19173c5ada610a5989151111163d28a67368362762534d8a8121ce95cf2bd5a 0.0s
=> CACHED [linux/amd64 build 2/2] RUN echo "I am running on linux/amd64, building for linux/arm/v7" > /log 0.0s
=> CACHED [linux/arm/v7 stage-1 2/2] COPY --from=build /log /log 0.0s
=> [linux/amd64 stage-1 1/2] FROM docker.io/library/alpine@sha256:c19173c5ada610a5989151111163d28a67368362762534d8a8121ce95cf2bd5a 0.0s
=> => resolve docker.io/library/alpine@sha256:c19173c5ada610a5989151111163d28a67368362762534d8a8121ce95cf2bd5a 0.0s
=> CACHED [linux/amd64 build 2/2] RUN echo "I am running on linux/amd64, building for linux/amd64" > /log 0.0s
=> CACHED [linux/amd64 stage-1 2/2] COPY --from=build /log /log 0.0s
=> exporting to image 13.4s
=> => exporting layers 0.0s
=> => exporting manifest sha256:9691c28fd9a98d735f05c913f61165f1367323eca6784a852d457fa1f74dab84 0.0s
=> => exporting config sha256:0682fde125dbb5923e494a1dfd6c807bc59d2e9fc7120b57e49074cc7ae7e9f4 0.0s
=> => exporting manifest sha256:59c54d4c1b1bee1bd2c23f38f9f2bffc292d0236a4032fba7e9be26fbe0d2802 0.0s
=> => exporting config sha256:ac7414caf47ea7db5cc95e5fa9cf65bb98ff8def55f22c08377ad76da4f59260 0.0s
=> => exporting manifest sha256:8f73236eead90974fa8ec0b15b5ae1b193786adbfc2d612bb1ab0c272957d3f8 0.0s
=> => exporting config sha256:59cb995bf069ab54813fb32e9bd039cafb3830eadf04cc23cb960e134468eb25 0.0s
=> => exporting manifest list sha256:72d368f9a6696dc9551ec250d8a2e54bab85b8d0cb784e81cb4a7742090890a3 0.0s
=> => pushing layers 10.7s
=> => pushing manifest for docker.io/yangpeng2468/test:latest
- 查看 linux/arm, linux/arm64, linux/amd64 镜像
$ docker buildx imagetools inspect yangpeng2468/test
Name: docker.io/yangpeng2468/test:latest
MediaType: application/vnd.docker.distribution.manifest.list.v2+json
Digest: sha256:72d368f9a6696dc9551ec250d8a2e54bab85b8d0cb784e81cb4a7742090890a3
Manifests:
Name: docker.io/yangpeng2468/test:latest@sha256:9691c28fd9a98d735f05c913f61165f1367323eca6784a852d457fa1f74dab84
MediaType: application/vnd.docker.distribution.manifest.v2+json
Platform: linux/arm/v7
Name: docker.io/yangpeng2468/test:latest@sha256:59c54d4c1b1bee1bd2c23f38f9f2bffc292d0236a4032fba7e9be26fbe0d2802
MediaType: application/vnd.docker.distribution.manifest.v2+json
Platform: linux/arm64
Name: docker.io/yangpeng2468/test:latest@sha256:8f73236eead90974fa8ec0b15b5ae1b193786adbfc2d612bb1ab0c272957d3f8
MediaType: application/vnd.docker.distribution.manifest.v2+json
Platform: linux/amd64
测试多平台镜像
由于我的环境是 linux/amd64，如果测试其它平台镜像，需要开启 binfmt_misc 功能
binfmt_misc开启方法
$ docker run --rm --privileged docker/binfmt:66f9012c56a8316f9244ffd7622d7c21c1f6f28d
- 查看
binfmt_misc设置是否正确
$ ls -la /proc/sys/fs/binfmt_misc/
-rw-r--r-- 1 root root 0 11月 29 20:45 qemu-aarch64
-rw-r--r-- 1 root root 0 11月 29 20:45 qemu-arm
-rw-r--r-- 1 root root 0 11月 29 20:45 qemu-ppc64le
-rw-r--r-- 1 root root 0 11月 29 20:45 qemu-s390x
--w------- 1 root root 0 11月 29 20:29 register
-rw-r--r-- 1 root root 0 11月 29 20:29 status
- 验证 linux/arm, linux/arm64, linux/amd64 镜像
$ docker run -it --rm docker.io/yangpeng2468/test:latest@sha256:9691c28fd9a98d735f05c913f61165f1367323eca6784a852d457fa1f74dab84
I am running on linux/amd64, building for linux/arm/v7
$ docker run -it --rm docker.io/yangpeng2468/test:latest@sha256:59c54d4c1b1bee1bd2c23f38f9f2bffc292d0236a4032fba7e9be26fbe0d2802
I am running on linux/amd64, building for linux/arm64
$ docker run -it --rm docker.io/yangpeng2468/test:latest@sha256:8f73236eead90974fa8ec0b15b5ae1b193786adbfc2d612bb1ab0c272957d3f8
I am running on linux/amd64, building for linux/amd64
总结
未来，buildx 很有可能成为 docker build 命令一部分，大家一起期待吧！
参考链接
- https://docs.docker.com/buildx/working-with-buildx/
- https://www.infoq.cn/article/V9Qj0fJj6HsGYQ0LpHxg
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