使用 docker buildx 構建多 cpu 架構鏡像 - 環境配置篇

使用 docker buildx 實現多平臺編譯

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docker registry api v2 支持多 CPU 架構鏡像.

同時 harbor v2 也實現了 docker registry api v2 的支持.

實現之後， 將不再有 cpu 架構困擾， 一個 docker pull image:tag 將自動適配可適配的平臺。真正做到海納百川，一騎當千。

0x01 準備

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• docker 開啓實驗模式
• buildx 插件
• qemu 模擬器
• Linux kernel >= 4.8

linux 系統內核

由於 binfmt_misc 機制開啓需要依賴 Linux kernel >= 4.8 。因此，在對 linux 系統操作選型上有一定要求。

建議使用 發行版 出場內核已經滿足需求的操作系統。而不是選擇自己升級系統內核。

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

參考文章:

• build multi architecture docker image with buildx

• 開啓實驗模式

當前 buildx 還是一個實驗模式, 如需要支持, 需要進行如下配置

1. 開啓實驗模式。修改 /etc/docker/daemon.json, 增加 experimental 字段， 如下。

# vi /etc/docker/daemon.json
{
    "experimental": true
}

安裝 buildx

1. 將 buildx 放到 ~/.docker/cli-plugins/ 目錄下

# 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/

安裝 qemu

下載並安裝 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

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創建 buildx builder

## 1. 創建指定名稱及指定平臺的builder
docker buildx create --use --platform=linux/amd64,linux/arm64 --name localbuilder

### 創建隨機名稱的 默認參數 builder
# docker buildx create --use

創建 Dockerfile 和 bakefile

目錄結構如下

# 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 執行編譯

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

當命令中省略 -f 參數時, 默認 bake 文件爲:

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

  執行結果

可以在 tangx/alpine:buildx-bake-hcl 看到，生成的鏡像， 支持了 5個 cpu 架構。

• 執行過程

# 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

使用命令行執行編譯

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

參數解釋

• docker buildx build : 主命令及子命令
• --platform=linux/amd64,linux/arm64 : 執行 cpu 架構
• --file : 指定 Dockerfile 的文件及路徑。省略則表示當前目錄下的 Dockerfile
• --tag : 鏡像名字及TAG
• --push : 完成並推送到倉庫
• alpine-bake : docker context 的目錄地址。

執行結果

略

相關文檔

---

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 支持的變量值

  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

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

troubleshoot

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

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

# 開始實驗模式 
# ~/docker/daemon.json
{
    "experimental": true
}

# docker version -f ''
## true

1. auto-push is currently not implemented for docker driver
   缺少 builder
   

# 創建一個 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
   參考 qemu-user-static #getting-started 執行以下命令。如果正常返回，則表示成功
   

$ 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