如何使用 Docker Hub 在特定架构上构建 Docker 映像？

Question

我在 Docker Hub 上有这些自动化构建：

作为参考，这里有两个 Dockerfile：

• https://github.com/rfgamaral/docker-gphotos-uploader/blob/master/Dockerfile
• https://github.com/rfgamaral/docker-gphotos-uploader/blob/master/Dockerfile.arm32v7

这是arm32v7 构建的构建日志：

Building in Docker Cloud's infrastructure...
Cloning into '.'...
Warning: Permanently added the RSA host key for IP address '192.30.253.113' to the list of known hosts.
Reset branch 'master'
Your branch is up-to-date with 'origin/master'.
Executing build hook...
Sending build context to Docker daemon 88.06kB
Step 1/17 : ARG ALPINE_VERSION="3.8"
Step 2/17 : ARG S6_OVERLAY_VERSION="1.21.7.0"
Step 3/17 : FROM golang:1.11-alpine${ALPINE_VERSION} AS builder
1.11-alpine3.8: Pulling from library/golang
169185f82c45: Pulling fs layer
34c29055ee42: Pulling fs layer
29802c64cdfc: Pulling fs layer
dd82873a5b09: Pulling fs layer
b711937b138a: Pulling fs layer
dd82873a5b09: Waiting
b711937b138a: Waiting
29802c64cdfc: Verifying Checksum
29802c64cdfc: Download complete
34c29055ee42: Verifying Checksum
34c29055ee42: Download complete
b711937b138a: Verifying Checksum
b711937b138a: Download complete
169185f82c45: Verifying Checksum
169185f82c45: Download complete
169185f82c45: Pull complete
34c29055ee42: Pull complete
29802c64cdfc: Pull complete
dd82873a5b09: Verifying Checksum
dd82873a5b09: Download complete
dd82873a5b09: Pull complete
b711937b138a: Pull complete
Digest: sha256:9657ef82d7ead12e0c88c7f4708e78b50c5fd3c1893ac0f2f0924ab98873aad8
Status: Downloaded newer image for golang:1.11-alpine3.8
---> be1230a1b343
Step 4/17 : RUN apk update && apk add --no-cache --virtual build-dependencies git && go get -u github.com/nmrshll/gphotos-uploader-cli/cmd/gphotos-uploader-cli && cd /go/src/github.com/nmrshll && rm -rf gphotos-uploader-cli && git clone https://github.com/rfgamaral/gphotos-uploader-cli.git --branch docker && rm -rf oauth2-noserver && git clone https://github.com/rfgamaral/oauth2-noserver.git --branch docker && cd gphotos-uploader-cli/cmd/gphotos-uploader-cli && GOOS=linux GOARCH=amd64 go build -ldflags='-w -s' -o /go/bin/gphotos-uploader-cli && apk del build-dependencies
---> Running in 79c1d68ad8b0
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/community/x86_64/APKINDEX.tar.gz
v3.8.2-53-g53558ad6fc [http://dl-cdn.alpinelinux.org/alpine/v3.8/main]
v3.8.2-53-g53558ad6fc [http://dl-cdn.alpinelinux.org/alpine/v3.8/community]
OK: 9544 distinct packages available
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/community/x86_64/APKINDEX.tar.gz
(1/7) Installing nghttp2-libs (1.32.0-r0)
(2/7) Installing libssh2 (1.8.0-r3)
(3/7) Installing libcurl (7.61.1-r1)
(4/7) Installing expat (2.2.5-r0)
(5/7) Installing pcre2 (10.31-r0)
(6/7) Installing git (2.18.1-r0)
(7/7) Installing build-dependencies (0)
Executing busybox-1.28.4-r3.trigger
OK: 19 MiB in 21 packages
Cloning into 'gphotos-uploader-cli'...
Cloning into 'oauth2-noserver'...
(1/7) Purging build-dependencies (0)
(2/7) Purging git (2.18.1-r0)
(3/7) Purging libcurl (7.61.1-r1)
(4/7) Purging nghttp2-libs (1.32.0-r0)
(5/7) Purging libssh2 (1.8.0-r3)
(6/7) Purging expat (2.2.5-r0)
(7/7) Purging pcre2 (10.31-r0)
Executing busybox-1.28.4-r3.trigger
OK: 5 MiB in 14 packages
Removing intermediate container 79c1d68ad8b0
---> 17b221a9ee49
Step 5/17 : FROM amd64/alpine:${ALPINE_VERSION}
3.8: Pulling from amd64/alpine
169185f82c45: Already exists
Digest: sha256:616d0d0ff1583933ed10a7b3b4492899942016c0577d43a1c506c0aad8ab4da8
Status: Downloaded newer image for amd64/alpine:3.8
---> 491e0ff7a8d5
Step 6/17 : LABEL maintainer="master@ricardoamaral.net"
---> Running in e58b7fcdb220
Removing intermediate container e58b7fcdb220
---> c525e340a42d
Step 7/17 : ARG BUILD_DATE
---> Running in 0a9417e1adcd
Removing intermediate container 0a9417e1adcd
---> 9f6c69125803
Step 8/17 : ARG S6_OVERLAY_VERSION
---> Running in 93a8cd6996b9
Removing intermediate container 93a8cd6996b9
---> 6034d93430da
Step 9/17 : ARG VCS_REF
---> Running in 8f6fc7d81c71
Removing intermediate container 8f6fc7d81c71
---> 74180d38dbc0
Step 10/17 : LABEL org.label-schema.build-date="${BUILD_DATE}" org.label-schema.description="Mass upload media folders to your Google Photos account with this Docker image." org.label-schema.name="rfgamaral/gphotos-uploader" org.label-schema.schema-version="1.0" org.label-schema.vcs-ref="${VCS_REF}" org.label-schema.vcs-url="https://github.com/rfgamaral/docker-gphotos-uploader.git"
---> Running in 08cf19c6f46a
Removing intermediate container 08cf19c6f46a
---> 106104e2ef17
Step 11/17 : ENV GPU_SCHEDULE="0 */8 * * *"
---> Running in edea63c892b9
Removing intermediate container edea63c892b9
---> d69ae92742d2
Step 12/17 : ADD https://github.com/just-containers/s6-overlay/releases/download/v${S6_OVERLAY_VERSION}/s6-overlay-amd64.tar.gz /tmp/
---> a7448cda217f
Step 13/17 : RUN apk update && apk add --no-cache curl && tar xzf /tmp/s6-overlay-amd64.tar.gz -C / && rm -rf /tmp/*
---> Running in 5d9ee7e3941d
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/community/x86_64/APKINDEX.tar.gz
v3.8.2-53-g53558ad6fc [http://dl-cdn.alpinelinux.org/alpine/v3.8/main]
v3.8.2-53-g53558ad6fc [http://dl-cdn.alpinelinux.org/alpine/v3.8/community]
OK: 9544 distinct packages available
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/community/x86_64/APKINDEX.tar.gz
(1/5) Installing ca-certificates (20171114-r3)
(2/5) Installing nghttp2-libs (1.32.0-r0)
(3/5) Installing libssh2 (1.8.0-r3)
(4/5) Installing libcurl (7.61.1-r1)
(5/5) Installing curl (7.61.1-r1)
Executing busybox-1.28.4-r3.trigger
Executing ca-certificates-20171114-r3.trigger
OK: 6 MiB in 18 packages
Removing intermediate container 5d9ee7e3941d
---> 14fc569893de
Step 14/17 : COPY --from=builder /go/bin/gphotos-uploader-cli /usr/local/bin/gphotos-uploader-cli
---> 32fa657de51c
Step 15/17 : COPY rootfs/ /
---> 1639f6e639b4
Step 16/17 : VOLUME ["/config", "/photos"]
---> Running in 440d1d13cd60
Removing intermediate container 440d1d13cd60
---> fd730f9c1ebb
Step 17/17 : ENTRYPOINT ["/init"]
---> Running in 197c889006b2
Removing intermediate container 197c889006b2
---> 4e66fc7b481d
Successfully built 4e66fc7b481d
Successfully tagged rfgamaral/gphotos-uploader:latest-arm32v7
Pushing index.docker.io/rfgamaral/gphotos-uploader:latest-arm32v7...
Done!
Build finished

如您所见，日志仅引用 amd64 而不是 arm32v7 或 armhf，它们在 Dockerfile.arm32v7 文件中显然存在。为什么 Docker Hub 会发生变化：

• arm32v7/alpine:${ALPINE_VERSION} 到 amd64/alpine:${ALPINE_VERSION}
• s6-overlay-armhf.tar.gz 到 s6-overlay-amd64.tar.gz
• GOARCH=arm GOARM=7 到 GOARCH=amd64

就像它使用Dockerfile 而不是Dockerfile.arm32v7 但是a）这不是我在自动构建配置中为“Dockerfile location”选择的内容，b）Docker Hub Builds 部分作为“Dockerfile”选项卡显示用于构建的 Dockerfile 并显示正确的。

这是 Docker Hub 上的错误还是我做错了什么？

Answer 1

经过一番研究，我解决了自己的问题...首先，我犯了一个愚蠢的错误，其次，我忘记了一件非常重要的事情。以下是我解决问题的方法：

愚蠢的错误

虽然我为每个自动构建指定了不同的Dockerfiles，但我还有一个build 钩子，它覆盖了docker build 命令，它默认为所有构建的Dockerfile，而不是选择正确的文件。

修复build挂钩文件：

#!/bin/bash

docker build \
    --file "${DOCKERFILE_PATH}" \
    --build-arg BUILD_DATE="$(date -u +"%Y-%m-%dT%H:%M:%SZ")" \
    --build-arg VCS_REF="$(git rev-parse --short HEAD)" \
    --tag "$IMAGE_NAME" \
    .

重要的事情

就像@JanGaraj 在他的回答中提到的那样，Docker Hub 在amd64 上运行，因此它不能为其他架构运行二进制文件。如何使用 Docker Hub 自动构建构建多架构镜像？在qemu-user-static 和更多钩子的帮助下。我在this GitHub issue 上找到了答案，但我会在此处发布针对我的具体用例的完整答案：

我的示例项目树：

.
├── Dockerfile
├── Dockerfile.aarch64
├── Dockerfile.armhf
└── hooks
    ├── build
    ├── post_checkout
    └── pre_build

post_checkout 挂钩文件：

#!/bin/bash

BUILD_ARCH=$(echo "${DOCKERFILE_PATH}" | cut -d '.' -f 2)

[ "${BUILD_ARCH}" == "Dockerfile" ] && \
    { echo 'qemu-user-static: Download not required for current arch'; exit 0; }

QEMU_USER_STATIC_ARCH=$([ "${BUILD_ARCH}" == "armhf" ] && echo "${BUILD_ARCH::-2}" || echo "${BUILD_ARCH}")
QEMU_USER_STATIC_DOWNLOAD_URL="https://github.com/multiarch/qemu-user-static/releases/download"
QEMU_USER_STATIC_LATEST_TAG=$(curl -s https://api.github.com/repos/multiarch/qemu-user-static/tags \
    | grep 'name.*v[0-9]' \
    | head -n 1 \
    | cut -d '"' -f 4)

curl -SL "${QEMU_USER_STATIC_DOWNLOAD_URL}/${QEMU_USER_STATIC_LATEST_TAG}/x86_64_qemu-${QEMU_USER_STATIC_ARCH}-static.tar.gz" \
    | tar xzv

pre_build 挂钩文件：

#!/bin/bash

BUILD_ARCH=$(echo "${DOCKERFILE_PATH}" | cut -d '.' -f 2)

[ "${BUILD_ARCH}" == "Dockerfile" ] && \
    { echo 'qemu-user-static: Registration not required for current arch'; exit 0; }

docker run --rm --privileged multiarch/qemu-user-static:register --reset

Dockerfile 文件：

FROM amd64/alpine:3.8
(...)

Dockerfile.aarch64 文件：

FROM arm64v8/alpine:3.8
COPY qemu-aarch64-static /usr/bin/
(...)

Dockerfile.armhf 文件：

FROM arm32v6/alpine:3.8
COPY qemu-arm-static /usr/bin/
(...)

就是这样！

Answer 2

如今，您还可以使用 docker buildx 为不同的架构进行构建，而无需为每个架构维护单独的 Dockerfile。 Building Multi-Architecture Docker Images With Buildx 描述了它是如何工作的。 基本上，你

1. 使用 fix-binary 标志在主机上的 binfmt_misc 中注册您的 QEMU 模拟器，以便它可以在容器中运行，而无需将其复制到容器文件系统中
2. 使用docker buildx build --platform linux/arm/v7 ... 指示构建器针对不同于您的构建主机的架构进行构建

Answer 3

Docker 镜像golang:1.11-alpine3.8 是多架构镜像。可用架构列表：

$ docker run --rm mplatform/mquery golang:1.11-alpine3.8
Image: golang:1.11-alpine3.8
 * Manifest List: Yes
 * Supported platforms:
   - linux/amd64
   - linux/arm/v6
   - linux/arm64
   - linux/386
   - linux/ppc64le
   - linux/s390x

所以第一个问题：平台arm32/v7 不适用于此 Docker 映像。 第二个问题：Docker daemon 会拉取平台镜像，和 Docker daemon 的平台是一样的。我猜Docker Hub运行在amd64，所以它会选择amd64。

我的建议：构建静态链接二进制文件 + 跨平台 Go 编译 (GOARCH=arm GOARM=7) + 使用 SCRATCH 基础镜像，您将能够使用 amd64 Docker 创建 arm7。