[Question] Which sources does --cache-to and --cache-from cache for?

[morlay]

dockerx version: 0.4.2

I expect to cache /go/pkg/mod in github workflow cross multi builds.

some dockerfile like above:

# syntax = docker/dockerfile:experimental

FROM golang:1.15 as builder

WORKDIR /go/src

# for trigger rebuild
ENV COMMIT_SHA=xxx 

RUN --mount=type=cache,sharing=locked,id=gomod,target=/go/pkg/mod go build

FROM busybox

COPY --from=builder /go/bin/app /go/bin/app

Then run script to build

# create builder every time like in ci.
docker buildx create --use

docker buildx build \
    --load \
    --planform linux/arm64,linux/amd64 \
    --cache-to type=local,dest=/tmp/.buildx-cache \
    --cache-from type=local,src=/tmp/.buildx-cache \
    --tag gobuild \
    --file Dockerfile .

The --mount=cache not work. /go/pkg/mod always empty (go mod will re download).

is --cache-from and --cache-to only cache the build layers?

--mount=type=cache works well if builder not re-create until gc cleanup.

if i want to cache the /go/pkg/mod, could i have to copy /var/lib/buildkit from buildkit container?

real-world demo https://github.com/querycap/istio/runs/1159405706

[FernandoMiguel]

--cache-from and --cache-to push all build layers to registry image/label of you choice, local or remote

[morlay]

so --mount=type=cache not be included？

[FernandoMiguel]

so --mount=type=cache not be included？

Only you know your setup, so you use the best cache mechanism for you.
You can use either or both

[morlay]

@FernandoMiguel

any suggestion in this case?.
i need cache /go/pkg/mod for multi workflows in build stage.

but the --cache-to couldn't expose the cached files (/var/lib/buildkit) to host.
and buildkit recreated when each workflow starts, all cached files in /var/lib/buildkit losts

buildx not provide way to mount host path for /var/lib/buildkit when create buildkit

[morlay]

mv to moby/buildkit#1673 for further discussion

[2063113624]

@morlay，我有几个js写的前端项目，想要用buildKit构建以减少npm install的时间。但是通过jenkins CI构建的时候总是报/app/node_moudles/目录下面找不到安装的依赖，你能帮忙给点建议吗？Dockerfile如下（文件中的一些变量可以忽略）：

# syntax = docker/dockerfile:experimental
FROM $COMPILE_IMAGE as builder
WORKDIR /app
COPY package.json package-lock.json /app
RUN --mount=type=cache,target=/app/node_modules,id=$image_name,sharing=private \
    $install
COPY . /app
RUN --mount=type=cache,target=/app/node_modules,id=$image_name,sharing=private \
    $compile
FROM nginx:1.20.2
COPY --from=builder /app/dist /usr/share/nginx/html
WORKDIR /usr/share/nginx/html
EXPOSE 80
CMD nginx -g "daemon off;"

镜像构建命令：

export "DOCKER_BUILDKIT=1" && docker build  -t $SERVICE_IMAGE:${image_tag}  .