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docs: use bind mounts in Go Dockerfile examples #22388

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docs: use bind mounts in Go Dockerfile examples
Juneezee Apr 8, 2025
cf728b4
Remove `go mod download` step
Juneezee Apr 11, 2025
9783174
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Juneezee Jul 23, 2025
5ed1d65
Merge branch 'docker:main' into go-mod-mounts
Juneezee Sep 27, 2025
a391c8e
Update docs/content/manuals/build/ci/github-actions/cache.md
Juneezee Sep 27, 2025
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1 change: 1 addition & 0 deletions content/manuals/build/cache/optimize.md
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Expand Up @@ -225,6 +225,7 @@ tool you're using. Here are a few examples:

```dockerfile
RUN --mount=type=cache,target=/go/pkg/mod \
--mount=type=cache,target=/root/.cache/go-build \
go build -o /app/hello
```

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10 changes: 4 additions & 6 deletions content/manuals/build/ci/github-actions/cache.md
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Expand Up @@ -197,13 +197,11 @@ Example Dockerfile in `build/package/Dockerfile`
FROM golang:1.21.1-alpine as base-build

WORKDIR /build
RUN go env -w GOMODCACHE=/root/.cache/go-build
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@thaJeztah thaJeztah May 8, 2025

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Wondering if this one would still be useful; the default would be ~/.cache/go-build, but as the mounts are hard-coded to a location, it could be useful to explicitly configure go to use a location (for the mounts).

Possibly it could be a custom path so that the cache-directory can be set up to a predictable location for situations where you want to run the build as a user (USER) that's not root 🤔


COPY go.mod go.sum ./
RUN --mount=type=cache,target=/root/.cache/go-build go mod download
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@thaJeztah thaJeztah May 8, 2025

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Perhaps @crazy-max or @tonistiigi have ideas on this part; yes, it looks like go mod download may download more; but it could depend on the situation; i.e., if all modules are downloaded, then possibly the cache could be re-used for multiple stages (instead of each stage downloading "just" the parts it needs).

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@crazy-max crazy-max Jul 23, 2025

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For projects that don't vendor the dependencies this command is still useful so we should keep it imo.

the cache could be re-used for multiple stages (instead of each stage downloading "just" the parts it needs).

For multi-stage but also if doing a multiplatform build it will download it once similar to https://github.com/docker/compose/blob/6a2d16bd106bd84065e790b5c2b111509e8a6fd9/Dockerfile#L50-L54


COPY ./src ./
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@thaJeztah thaJeztah May 8, 2025

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Also double-checking with @crazy-max and @tonistiigi on this one; i.e., if copying the source was intentional here (restoring cache or otherwise?).

These are always tricky as there's no "single" rule, some bits may depend on your situation.

RUN --mount=type=cache,target=/root/.cache/go-build go build -o /bin/app /build/src
RUN --mount=type=cache,target=/go/pkg/mod \
--mount=type=cache,target=/root/.cache/go-build \
--mount=type=bind,target=. \
go build -o /bin/app /build/src
...
```

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6 changes: 1 addition & 5 deletions content/manuals/extensions/extensions-sdk/build/backend-extension-tutorial.md
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Expand Up @@ -190,13 +190,9 @@ FROM node:17.7-alpine3.14 AS client-builder
FROM golang:1.17-alpine AS builder
ENV CGO_ENABLED=0
WORKDIR /backend
COPY vm/go.* .
RUN --mount=type=cache,target=/go/pkg/mod \
--mount=type=cache,target=/root/.cache/go-build \
go mod download
COPY vm/. .
RUN --mount=type=cache,target=/go/pkg/mod \
--mount=type=cache,target=/root/.cache/go-build \
--mount=type=bind,source=vm/.,target=. \
go build -trimpath -ldflags="-s -w" -o bin/service

FROM alpine:3.15
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3 changes: 0 additions & 3 deletions hack/releaser/Dockerfile
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Expand Up @@ -8,9 +8,6 @@ FROM golang:${GO_VERSION}-alpine AS base
RUN apk add --no-cache openssl
ENV CGO_ENABLED=0
WORKDIR /src
COPY go.mod go.sum ./
RUN --mount=type=cache,target=/go/pkg/mod \
go mod download

FROM base AS releaser
RUN --mount=type=bind,target=. \
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