英文:
How to pre-build all required modules and cache them
问题
在构建 Docker 镜像时，我知道我们可以添加一个层来缓存依赖项。但是依赖项需要被构建。这一步非常耗时，在我的机器上，仅构建 sqlite3 就需要大约 30 秒。
我也知道可以使用 go build github.com/mattn/go-sqlite3 来构建特定的依赖项，但是否有办法预先构建 go.mod 中列出的所有依赖项呢？
我在这里找到了同样的问题链接，但是没有答案。
英文:
When buliding a Docker image, I know we can add a layer to cache dependencies. But the dependency needs to be built. This step is quite time-consuming, on my machine it takes about 30 seconds to build sqlite3 alone.
I also know I can use go build github.com/mattn/go-sqlite3 to build a specific dependency, but is there any way to pre-build all the dependencies list in go.mod?
I found the same question about this here, but there is no answer.
答案1
得分: 5
Docker在这个确切的主题上提供了文档，在这里。建议按照以下方式组织你的Dockerfile：
FROM --platform=${BUILDPLATFORM} docker.io/golang:1.16.7-alpine AS build
ARG TARGETOS
ARG TARGETARCH
WORKDIR /src
ENV CGO_ENABLED=0
COPY go.* .
RUN go mod download
COPY . .
RUN --mount=type=cache,target=/root/.cache/go-build \
GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build -o /out/example .
FROM scratch
COPY --from=build /out/example /
其中很多都是样板代码，如果你只构建单个架构，可以删除这些部分；与缓存相关的部分只有：
FROM docker.io/golang:1.16.7-alpine AS build
WORKDIR /src
COPY go.* .
RUN go mod download
COPY . .
RUN --mount=type=cache,target=/root/.cache/go-build go build -o /out/example .
FROM scratch
COPY --from=build /out/example /
这会在/root/.cache/go-build上挂载一个缓存目录，这是go构建缓存的默认位置。第一次构建镜像时，它会填充这个缓存。后续的构建将重用缓存文件。
为了使其工作，你必须使用DOCKER_BUILDKIT=1进行构建，例如：
DOCKER_BUILDKIT=1 docker build -t myimage .
或者使用docker buildx：
docker buildx build -t myimage .
我在本地测试过，似乎按预期工作（我已经验证了在第一次构建之外的构建中，在运行go build之前，go-build缓存目录已经填充）。
英文:
Docker provides documentation on this exact topic here. The suggestion is to structure your Dockerfile like this:
FROM --platform=${BUILDPLATFORM} docker.io/golang:1.16.7-alpine AS build
ARG TARGETOS
ARG TARGETARCH
WORKDIR /src
ENV CGO_ENABLED=0
COPY go.* .
RUN go mod download
COPY . .
RUN --mount=type=cache,target=/root/.cache/go-build \
GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build -o /out/example .
FROM scratch
COPY --from=build /out/example /
A lot of that is boilerplate you can remove if you're only building for a single architecture; the parts related to caching are really only:
FROM docker.io/golang:1.16.7-alpine AS build
WORKDIR /src
COPY go.* .
RUN go mod download
COPY . .
RUN --mount=type=cache,target=/root/.cache/go-build go build -o /out/example .
FROM scratch
COPY --from=build /out/example /
This mounts a cache directory on /root/.cache/go-build, which is the default location for the go build cache. The first time you build your image it will populate this cache. Subsequent builds will re-use the cached files.
For this to work, you must build with DOCKER_BUILDKIT=1, i.e.:
DOCKER_BUILDKIT=1 docker build -t myimage .
Or use docker buildx:
docker buildx build -t myimage .
I have tested this out locally and it seems to work as intended (I have verified that in builds other than the first one, the go-build cache directory is populated prior to running go build).
答案2
得分: -1
这在Docker中没有经过测试，但应该可以工作。它可能可以进一步优化，或者修改以在更受限制的构建环境中工作。
RUN go mod download && go list -f '{{ join .Deps "\n" }}' ./... | sort -u | grep -v '<your package import path>' | xargs go build
英文:
This isn't tested within Docker, but should work. It can likely be optimized further, though, or modified to work in more limited build environments
RUN go mod download && go list -f '{{ join .Deps "\n" }}' ./... | sort -u | grep -v '<your package import path>' | xargs go build
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