使用 docker buildx 实现多平台编译


docker registry api v2 支持多 CPU 架构镜像.

同时 harbor v2 也实现了 docker registry api v2 的支持.

实现之后, 将不再有 cpu 架构困扰, 一个 docker pull image:tag 将自动适配可适配的平台。真正做到海纳百川,一骑当千。

0x01 准备


  • docker 开启实验模式
  • buildx 插件
  • qemu 模拟器
  • Linux kernel >= 4.8

linux 系统内核

由于 binfmt_misc 机制开启需要依赖 Linux kernel >= 4.8 。因此,在对 linux 系统操作选型上有一定要求。

建议使用 发行版 进场内核已经知足需求的操作系统。而不是选择自己升级系统内核。

  • ubuntu:18.04 LTS 及以上
  • debian:10 及以上

参考文章:

  • build multi architecture docker image with buildx
  • 开启实验模式

当前 buildx 照样一个实验模式, 如需要支持, 需要举行如下设置

  1. 开启实验模式。修改 /etc/docker/daemon.json, 增添 experimental 字段, 如下。
# vi /etc/docker/daemon.json
{
    "experimental": true
}

安装 buildx

  1. 将 buildx 放到 ~/.docker/cli-plugins/ 目录下
# https://github.com/docker/buildx/blob/master/README.md#docker-ce

BUILDX_VERSION=v0.4.1
ARCH=$(uname -m)
[ "${ARCH}" == "x86_64" ] && ARCH=amd64
[ "${ARCH}" == "aarch64" ] && ARCH=arm64

mkdir -p ~/.docker/cli-plugins
wget -c https://github.com/docker/buildx/releases/download/${BUILDX_VERSION}/buildx-${BUILDX_VERSION}.linux-${ARCH} -O docker-buildx\
    && chmod +x docker-buildx   \
    && mv docker-buildx ~/.docker/cli-plugins/

安装 qemu

下载并安装 qumu 到 /usr/bin/qemu-$(uname -m)-static

# https://github.com/multiarch/qemu-user-static#multiarchqemu-user-static-images

QEMU_VERSION=v5.0.0-2

wget -c https://github.com/multiarch/qemu-user-static/releases/download/${QEMU_VERSION}/qemu-$(uname -m)-static -O qemu-$(uname -m)-static \
    && chmod +x qemu-$(uname -m)-static     \
    && mv qemu-$(uname -m)-static /usr/local/bin/qemu-$(uname -m)-static

0x02 example


建立 buildx builder

## 1. 建立指定名称及指定平台的builder
docker buildx create --use --platform=linux/amd64,linux/arm64 --name localbuilder

### 建立随机名称的 默认参数 builder
# docker buildx create --use

建立 Dockerfile 和 bakefile

目录结构如下

# tree
# .
# ├── alpine-bake
# │   └── alpine.Dockerfile
# └── bake.hcl
  • alpine-bake/alpine.Dockerfile
FROM alpine:3.12

ARG TARGETARCH
RUN echo "TARGETARCH is $TARGETARCH"
  • docker-bake.hcl
group "default" {
    targets = ["alpine"]
}

target "alpine" {
    context = "./alpine-bake"
    dockerfile = "alpine.Dockerfile"
    tags = ["docker.io/tangx/alpine:buildx-bake-hcl"]
    platforms = ["linux/amd64", "linux/arm64", "linux/arm/v6", "linux/arm/v7", "linux/s390x"]
    ## push to registry
    output = ["type=registry"]
    ## pull base image always
    pull = true
}

target "debian" {
    context = "./debian-bake"
    ## default: Dockerfile
    # dockerfile = "Dockerfile"  
    tags = ["docker.io/tangx/debian:buildx-bake-hcl"]

    platforms = ["linux/amd64", "linux/arm64", "linux/arm/v6", "linux/arm/v7", "linux/s390x"]

    ## push to registry
    output = ["type=registry"]
    ## pull base image always
    pull = true
}

使用 bake 执行编译

docker buildx bake -f bake.hcl # -f alias to bake

当下令中省略 -f 参数时, 默认 bake 文件为:

,

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,
  • docker-bake.json
  • docker-bake.hcl
  • docker-compose.yaml

    执行效果

可以在 tangx/alpine:buildx-bake-hcl 看到,天生的镜像, 支持了 5个 cpu 架构。

  • 执行历程
# docker buildx bake -f bake.hcl

[+] Building 46.9s (19/19) FINISHED
 => [internal] booting buildkit              3.3s
 => [internal] load build definition from alpine.Dockerfile            0.1s
 => [internal] load .dockerignore            0.1s
 => [linux/arm/v6 internal] load metadata for docker.io/library/alpine:3.12        13.1s
 => [linux/arm64 internal] load metadata for docker.io/library/alpine:3.12         10.4s
 => [linux/amd64 internal] load metadata for docker.io/library/alpine:3.12         13.1s
 => [linux/s390x internal] load metadata for docker.io/library/alpine:3.12         13.1s
 => [linux/arm/v7 internal] load metadata for docker.io/library/alpine:3.12        13.1s
 => [linux/amd64 1/2] FROM docker.io/library/alpine:3.12@sha256:c0e9560cda118f9ec63ddefb4a173a2b2a0347082d7dff7dc14272e7841a5b5a        6.1s
 => [linux/arm/v7 1/2] FROM docker.io/library/alpine:3.12@sha256:c0e9560cda118f9ec63ddefb4a173a2b2a0347082d7dff7dc14272e7841a5b5a       5.9s
 => [linux/arm/v6 1/2] FROM docker.io/library/alpine:3.12@sha256:c0e9560cda118f9ec63ddefb4a173a2b2a0347082d7dff7dc14272e7841a5b5a       6.0s
 => [linux/arm64 1/2] FROM docker.io/library/alpine:3.12@sha256:c0e9560cda118f9ec63ddefb4a173a2b2a0347082d7dff7dc14272e7841a5b5a        6.1s
 => [linux/s390x 1/2] FROM docker.io/library/alpine:3.12@sha256:c0e9560cda118f9ec63ddefb4a173a2b2a0347082d7dff7dc14272e7841a5b5a        6.3s
 => [linux/arm/v7 2/2] RUN echo "TARGETARCH is arm"       0.9s
 => [linux/arm/v6 2/2] RUN echo "TARGETARCH is arm"       0.8s
 => [linux/amd64 2/2] RUN echo "TARGETARCH is amd64"      0.7s
 => [linux/arm64 2/2] RUN echo "TARGETARCH is arm64"      0.5s
 => [linux/s390x 2/2] RUN echo "TARGETARCH is s390x"      0.4s
 => exporting to image         22.9s

使用下令行执行编译

# docker buildx build --platform=linux/amd64,linux/arm64 --file alpine-bake/alpine.Dockerfile --tag tangx/alpine:multi-arch --push alpine-bake/

参数注释

  • docker buildx build : 主下令及子下令
  • --platform=linux/amd64,linux/arm64 : 执行 cpu 架构
  • --file : 指定 Dockerfile 的文件及路径。省略则示意当前目录下的 Dockerfile
  • --tag : 镜像名字及TAG
  • --push : 完成并推送到堆栈
  • alpine-bake : docker context 的目录地址。

执行效果

相关文档


  1. buildx
  • buildx README.md in Github.com
  • buildx Documents in docs.docker.com

2 . buildx bake

  • buildx bake hcl variables
  • buildx bake hcl examples

3 .docker

  • builder arg
  • docker manifest
  • docker register v2
  • global platform args

    buildx hcl 支持的变量值

    type Target struct {
    Name string `json:"-" hcl:"name,label"`
    
    // Inherits is the only field that cannot be overridden with --set
    Inherits []string `json:"inherits,omitempty" hcl:"inherits,optional"`
    
    Context    *string           `json:"context,omitempty" hcl:"context,optional"`
    Dockerfile *string           `json:"dockerfile,omitempty" hcl:"dockerfile,optional"`
    Args       map[string]string `json:"args,omitempty" hcl:"args,optional"`
    Labels     map[string]string `json:"labels,omitempty" hcl:"labels,optional"`
    Tags       []string          `json:"tags,omitempty" hcl:"tags,optional"`
    CacheFrom  []string          `json:"cache-from,omitempty"  hcl:"cache-from,optional"`
    CacheTo    []string          `json:"cache-to,omitempty"  hcl:"cache-to,optional"`
    Target     *string           `json:"target,omitempty" hcl:"target,optional"`
    Secrets    []string          `json:"secret,omitempty" hcl:"secret,optional"`
    SSH        []string          `json:"ssh,omitempty" hcl:"ssh,optional"`
    Platforms  []string          `json:"platforms,omitempty" hcl:"platforms,optional"`
    Outputs    []string          `json:"output,omitempty" hcl:"output,optional"`
    Pull       *bool             `json:"pull,omitempty" hcl:"pull,optional"`
    NoCache    *bool             `json:"no-cache,omitempty" hcl:"no-cache,optional"`
    // IMPORTANT: if you add more fields here, do not forget to update newOverrides and README.
    }

    在 github action 上使用 buildx


https://github.com/marketplace/actions/customizable-docker-buildx

troubleshoot


  1. multiple platforms feature is currently not supported for docker driver

当前模式不支持 buildx : https://github.com/docker/cli/blob/master/experimental/README.md

# 最先实验模式 
# ~/docker/daemon.json
{
    "experimental": true
}

# docker version -f ''
## true
  1. auto-push is currently not implemented for docker driver
    缺少 builder
# 建立一个 builder 
docker buildx create --use # a random name

docker buildx create --user --name specified_name # specified name
  1. failed to solve: rpc error: code = Unknown desc = failed to load LLB: runtime execution on platform linux/arm64 not supported
    参考 qemu-user-static #getting-started 执行以下下令。若是正常返回,则示意乐成
$ uname -m
x86_64

$ docker run --rm -t arm64v8/ubuntu uname -m
standard_init_linux.go:211: exec user process caused "exec format error"

$ docker run --rm --privileged multiarch/qemu-user-static --reset -p yes

$ docker run --rm -t arm64v8/ubuntu uname -m
aarch64
  • https://github.com/multiarch/qemu-user-static#getting-started
  • https://github.com/docker/buildx/issues/132#issuecomment-521759117