docs: use bind mounts in Go Dockerfile examples

[Juneezee]

Description

I remembered there used to be a page (https://docs.docker.com/build/guide/mounts/) that demonstrated how to use both bind mounts and cache mounts together in a Dockerfile for a Go application. However, that page was removed in https://github.com/docker/docs/pull/20715, and the new page (https://docs.docker.com/build/cache/optimize/) now separates the examples for bind mounts and cache mounts.

https://github.com/docker/docs/blob/91b324fb4dfd31ff5a0f6a8bd55f1c667619ca2b/content/build/guide/mounts.md?plain=1#L185-L194

It would be great if the remaining Go Dockerfile examples could show how to use both bind mounts and cache mounts together ~~specifically for go.mod and go.sum. This combination was really helpful for improving build performance and clarity when using Docker for Go development.~~ (See https://github.com/docker/docs/pull/22388#issuecomment-2795683162 for updtae)

Related issues or tickets

• https://github.com/docker/docs/pull/20715

Reviews

• [ ] Technical review
• [ ] Editorial review
• [ ] Product review

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[Juneezee]

UPDATE: I have removed the go mod download step in commit cf728b44d9dc054e3b042b6a948f962888d06855.

go build will automatically download module dependencies. In many cases, that is a much smaller set of modules than what is downloaded by go mod download. I found a great explanation on StackOverflow here: https://stackoverflow.com/a/68172023/7902371

Using the https://github.com/github/github-mcp-server Go application as an example below.

Size of GOMODCACHE with go mod download:

~/Desktop/github/github-mcp-server docker ❯ go clean -i -r -cache -modcache

~/Desktop/github/github-mcp-server docker ❯ go mod download

~/Desktop/github/github-mcp-server docker ❯ du -sh ~/go/pkg/mod
186M	/home/jun/go/pkg/mod

Size of GOMODCACHE with go build:

~/Desktop/github/github-mcp-server docker !1 ❯ go clean -i -r -cache -modcache

~/Desktop/github/github-mcp-server docker !1 ❯ CGO_ENABLED=0 go build -ldflags="-s -w" cmd/github-mcp-server/main.go
go: downloading github.com/spf13/viper v1.20.1
go: downloading github.com/mark3labs/mcp-go v0.18.0
go: downloading github.com/google/go-github/v69 v69.2.0
go: downloading github.com/sirupsen/logrus v1.9.3
go: downloading github.com/spf13/cobra v1.9.1
go: downloading golang.org/x/sys v0.31.0
go: downloading github.com/spf13/afero v1.14.0
go: downloading github.com/fsnotify/fsnotify v1.8.0
go: downloading github.com/spf13/cast v1.7.1
go: downloading github.com/go-viper/mapstructure/v2 v2.2.1
go: downloading github.com/subosito/gotenv v1.6.0
go: downloading gopkg.in/yaml.v3 v3.0.1
go: downloading github.com/spf13/pflag v1.0.6
go: downloading github.com/pelletier/go-toml/v2 v2.2.3
go: downloading github.com/sagikazarmark/locafero v0.9.0
go: downloading golang.org/x/text v0.23.0
go: downloading github.com/google/uuid v1.6.0
go: downloading github.com/yosida95/uritemplate/v3 v3.0.2
go: downloading github.com/sourcegraph/conc v0.3.0
go: downloading github.com/google/go-querystring v1.1.0

~/Desktop/github/github-mcp-server docker !1 ?1 ❯ du -sh ~/go/pkg/mod
80M	/home/jun/go/pkg/mod

Running go build results in a smaller GOMODCACHE (~80 MB) compared to go mod download (~186 MB).

[Juneezee]

Hi @aevesdocker @crazy-max, when you have a moment, could you take a quick look at this PR and let me know if it would be a worthwhile improvement to the documentation?

Thanks :blush:

[Juneezee]

Hi @thaJeztah and @crazy-max,

It's been a while. I wanted to follow up on this PR since I addressed the previous review comments.

Is there anything else I should do from my side, or do you think the PR is ready for the next review round/merge?

Thank you!

/cc @dvdksn (Author of PR #20715)