是否可以在没有 docker buildx 的情况下（手动）构建多架构 docker 镜像？

Question

我有一个 Golang 项目，已构建并放入scratch镜像中：

# Build binary
FROM golang:1.17-alpine AS build-env
ADD . /app
WORKDIR /app
RUN env CGO_ENABLED=0 go build -ldflags="-s -w" -o myapp ./cmd/myapp/main.go

# Create image
FROM scratch
COPY --from=build-env /app/myapp /
ENTRYPOINT ["/myapp"]

由于 Golang 允许针对多种架构进行交叉编译（并且比在模拟环境中构建要快得多），所以我想做这样的事情：

# Build binary
FROM golang:1.17-alpine AS build-env
ADD . /app
WORKDIR /app
RUN env CGO_ENABLED=0 GOOS=linux GOARCH=386 go build -ldflags="-s -w" -o myapp_linux_i386 ./cmd/myapp/main.go             # Linux 32bit
RUN env CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -ldflags="-s -w" -o myapp_linux_x86_64 ./cmd/myapp/main.go         # Linux 64bit
RUN env CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=5 go build -ldflags="-s -w" -o myapp_linux_arm ./cmd/myapp/main.go      # Linux armv5/armel/arm (it also works on armv6)
RUN env CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=7 go build -ldflags="-s -w" -o myapp_linux_armhf ./cmd/myapp/main.go    # Linux armv7/armhf
RUN env CGO_ENABLED=0 GOOS=linux GOARCH=arm64 go build -ldflags="-s -w" -o myapp_linux_aarch64 ./cmd/myapp/main.go        # Linux armv8/aarch64
RUN env CGO_ENABLED=0 GOOS=freebsd GOARCH=amd64 go build -ldflags="-s -w" -o myapp_freebsd_x86_64 ./cmd/myapp/main.go     # FreeBSD 64bit
RUN env CGO_ENABLED=0 GOOS=darwin GOARCH=amd64 go build -ldflags="-s -w" -o myapp_darwin_x86_64 ./cmd/myapp/main.go       # Darwin 64bit
RUN env CGO_ENABLED=0 GOOS=darwin GOARCH=arm64 go build -ldflags="-s -w" -o myapp_darwin_aarch64 ./cmd/myapp/main.go      # Darwin armv8/aarch64
RUN env CGO_ENABLED=0 GOOS=windows GOARCH=386 go build -ldflags="-s -w" -o myapp_windows_i386.exe ./cmd/myapp/main.go     # Windows 32bit
RUN env CGO_ENABLED=0 GOOS=windows GOARCH=amd64 go build -ldflags="-s -w" -o myapp_windows_x86_64.exe ./cmd/myapp/main.go # Windows 64bit

但是如何创建和推送多架构 docker 镜像呢？

# Create image
...

Answer 1

从问题来看，听起来不太像您想避免 buildx，而更像是您想避免在解释器下运行编译器，而是使用 Go 的内置交叉编译功能。这是内置于 buildx 中的：

# Build binary
FROM --platform=$BUILDPLATFORM golang:1.17-alpine AS build-env
ADD . /app
WORKDIR /app
ARG TARGETOS
ARG TARGETARCH
RUN CGO_ENABLED=0 GOOS=${TARGETOS} GOARCH=${TARGETARCH} \
    go build -ldflags="-s -w" -o myapp ./cmd/myapp/main.go

# Create image
FROM scratch
COPY --from=build-env /app/myapp /
ENTRYPOINT ["/myapp"]

它--platform在您正在构建的平台上运行第一阶段。TARGETOS 和 TARGETARCH 是 buildkit 的内置参数。然后您可以使用以下命令进行构建：

# Build binary
FROM --platform=$BUILDPLATFORM golang:1.17-alpine AS build-env
ADD . /app
WORKDIR /app
ARG TARGETOS
ARG TARGETARCH
RUN CGO_ENABLED=0 GOOS=${TARGETOS} GOARCH=${TARGETARCH} \
    go build -ldflags="-s -w" -o myapp ./cmd/myapp/main.go

# Create image
FROM scratch
COPY --from=build-env /app/myapp /
ENTRYPOINT ["/myapp"]

请注意，docker 不支持 MacOS，它在该平台上的 Linux VM 中运行。而且我也不相信 windows/386 是有效的，我只见过 amd64 上的 docker 并且可能支持 arm64。

除此之外，还有多种方式可以推送多平台清单。docker 内置了docker manifest。或者您可以自己生成清单并使用 API 调用将其推送到注册表（如果您想了解底层详细信息，请参阅 OCI 的图像规范和分发规范）。但如果你有 docker，buildx 就是最简单的按钮。