docker buildx跨架构构建(x86_64构建aarch64镜像)

简介

Docker Buildx 是 Docker 团队为 Docker 引擎设计的一个工具，用于支持构建和管理多平台的容器镜像。它扩展了 Docker 构建工具，使得可以跨多个不同的架构和操作系统进行构建。

第一步 先交叉编译一个aarch64的HelloWorld程序。

准备一个用于跨架构的Dockerfile文件

vi Dockerfile

FROM ubuntu:20.04

COPY main  /app/main

WORKDIR /app

CMD ["/app/main"]

使用docker buildx命令构建aarch64架构的镜像。

docker buildx build --platform linux/arm64 -t test:0.1 --load .

# root @ liuyuelong-System-Product-Name in ~/workspace/cross_test/src/main on git:master x [17:28:46] 
$ docker buildx build --platform linux/arm64 -t aarch64_images:1.0 --load .
[+] Building 3.4s (9/9) FINISHED                                                                                docker-container:elegant_davinci
 => [internal] load build definition from Dockerfile                                                                                        0.0s
 => => transferring dockerfile: 111B                                                                                                        0.0s
 => [internal] load .dockerignore                                                                                                           0.0s
 => => transferring context: 2B                                                                                                             0.0s
 => [internal] load metadata for docker.io/library/ubuntu:20.04                                                                             2.8s
 => [internal] load build context                                                                                                           0.0s
 => => transferring context: 14.27kB                                                                                                        0.0s
 => CACHED [1/3] FROM docker.io/library/ubuntu:20.04@sha256:ed4a42283d9943135ed87d4ee34e542f7f5ad9ecf2f244870e23122f703f91c2                0.0s
 => => resolve docker.io/library/ubuntu:20.04@sha256:ed4a42283d9943135ed87d4ee34e542f7f5ad9ecf2f244870e23122f703f91c2                       0.0s
 => [2/3] COPY main  /app/main                                                                                                              0.0s
 => [3/3] WORKDIR /app                                                                                                                      0.0s
 => exporting to oci image format                                                                                                           0.3s
 => => exporting layers                                                                                                                     0.2s
 => => exporting manifest sha256:9354e37bfcc69a2408f10323d76afaa40e96fb04f5ef6260d23ca6f17ec86dad                                           0.0s
 => => exporting config sha256:a858b4c183e0ebdc2e8b217c5557e1f3fb3aebc3df98a0f8cfd5b68673005052                                             0.0s
 => => sending tarball                                                                                                                      0.1s
 => importing to docker                                                                                                                     0.0s

# root @ liuyuelong-System-Product-Name in ~/workspace/cross_test/src/main on git:master x [17:31:22] 
$ docker images | grep aarch64_images
aarch64_images                                    1.0               a858b4c183e0   43 seconds ago      65.7MB

查看镜像具体详细信息（确定镜像是ARM架构）

# root @ liuyuelong-System-Product-Name in ~/workspace/cross_test/src/main on git:master x [17:32:10] 
$ docker inspect aarch64_images:1.0
[
    {
        "Id": "sha256:a858b4c183e0ebdc2e8b217c5557e1f3fb3aebc3df98a0f8cfd5b68673005052",
        "RepoTags": [
            "aarch64_images:1.0"
        ],
        "RepoDigests": [],
        "Parent": "",
        "Comment": "buildkit.dockerfile.v0",
        "Created": "2023-11-30T09:31:22.44138137Z",
        "Container": "",
        "ContainerConfig": {
            "Hostname": "",
            "Domainname": "",
            "User": "",
            "AttachStdin": false,
            "AttachStdout": false,
            "AttachStderr": false,
            "Tty": false,
            "OpenStdin": false,
            "StdinOnce": false,
            "Env": null,
            "Cmd": null,
            "Image": "",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": null
        },
        "DockerVersion": "",
        "Author": "",
        "Config": {
            "Hostname": "",
            "Domainname": "",
            "User": "",
            "AttachStdin": false,
            "AttachStdout": false,
            "AttachStderr": false,
            "Tty": false,
            "OpenStdin": false,
            "StdinOnce": false,
            "Env": [
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
            ],
            "Cmd": [
                "/app/main"
            ],
            "ArgsEscaped": true,
            "Image": "",
            "Volumes": null,
            "WorkingDir": "/app",
            "Entrypoint": null,
            "OnBuild": null,
            "Labels": {
                "org.opencontainers.image.ref.name": "ubuntu",
                "org.opencontainers.image.version": "20.04"
            }
        },
        "Architecture": "arm64",
        "Os": "linux",
        "Size": 65692279,
        "VirtualSize": 65692279,
        "GraphDriver": {
            "Data": {
                "LowerDir": "/var/lib/docker/overlay2/31cdebbee3d9a5cb5222804c1ca5759ce9d9dacc1aa94c9ff5317fe13989aca1/diff",
                "MergedDir": "/var/lib/docker/overlay2/6c1bad2064ca4947f86e3a9438c25e7c926cb7d4d65c3cececcd0ce7236ec3cc/merged",
                "UpperDir": "/var/lib/docker/overlay2/6c1bad2064ca4947f86e3a9438c25e7c926cb7d4d65c3cececcd0ce7236ec3cc/diff",
                "WorkDir": "/var/lib/docker/overlay2/6c1bad2064ca4947f86e3a9438c25e7c926cb7d4d65c3cececcd0ce7236ec3cc/work"
            },
            "Name": "overlay2"
        },
        "RootFS": {
            "Type": "layers",
            "Layers": [
                "sha256:701ccb11c0525a289459678e1ef3e9269b62737fafb033db91061ae53a0e9c1e",
                "sha256:2ebde9a9a90f240d14d223cb6d6ac61e209f0e871973ceb6c421b3b0569c09d8"
            ]
        },
        "Metadata": {
            "LastTagTime": "0001-01-01T00:00:00Z"
        }
    }
]

"Architecture": "arm64", 架构没有问题

测试（通过）

导出镜像
docker save aarch64_images:1.0 -o aarch64_images.img
在aarch64架构下安装镜像
docker load -i aarch64_images.img
运行测试

# docker run --rm aarch64_images:1.0
Hello World!

测试通过

小技巧（避免每次下载aarch64架构的基础镜像）

docker buildx create --use
create => Create a new builder instance 创建一个新的构造器实例
–use => Set the current builder instance 使用创建的构建器实例作为当前的构造器

创建实例后，如果使用的话，构造器就会被激活，并以容器的形式运行，在这个容器中，在构建过程中下载的基础镜像会被保存在容器中，再次构建，不需要重新下载基础镜像。

也可以使用命令管理构造器