Go feature leaves ~994 MB of build cache in /tmp/gotools after installing tools

[dkwgit]

Description

The Go feature's install.sh script leaves approximately 994 MB of Go build artifacts in /tmp/gotools after compiling Go tools. The script sets GOPATH=/tmp/gotools and GOCACHE=/tmp/gotools/cache as temporary build locations, moves the compiled binaries out of /tmp/gotools/bin/, but fails to clean up the module cache and build cache directories.

Root Cause

In src/go/install.sh, the cleanup logic is:

The rm -rf /tmp/gotools is inside the if [ -d /tmp/gotools/bin ] conditional. If this block executes successfully, the rm should remove the directory — but in practice, /tmp/gotools/cache (612 MB) and /tmp/gotools/pkg (383 MB) remain in the final image layer.

It appears the rm -rf /tmp/gotools either fails silently or the cache directories are recreated after this point (possibly by the subsequent golangci-lint installation which also uses Go tooling).

Impact

994 MB of unnecessary data baked into every image using this feature
/tmp/gotools/cache: 612 MB (Go build cache)
/tmp/gotools/pkg: 383 MB (Go module cache)

Steps to Reproduce

• Create a devcontainer with the Go feature:
• Build the devcontainer image
• Inspect the image: docker run --rm du -sh /tmp/gotools/*

Expected Behavior

/tmp/gotools should be completely removed after tool installation.

Suggested Fix

Add a cleanup after the golangci-lint install block (after the fi closing the INSTALL_GO_TOOLS conditional):

Environment

Feature: ghcr.io/devcontainers/features/go:1 (v1.3.2)
Base image: mcr.microsoft.com/devcontainers/base:ubuntu
Go version: latest (1.24.x)
Architecture: x86_64 / amd64

[gvatsal60]

Hi @dkwgit 👋

I’ve opened a pull request to address this issue by ensuring the temporary Go tools directory (/tmp/gotools) is properly cleaned up after installation to prevent leftover build cache from increasing image size.

PR: #1588

Could you please take a look when you have a moment? Happy to make any changes if needed.

Thanks!

[dkwgit]

@gvatsal60

Hi @dkwgit 👋

I’ve opened a pull request to address this issue by ensuring the temporary Go tools directory (/tmp/gotools) is properly cleaned up after installation to prevent leftover build cache from increasing image size.

PR: #1588

Could you please take a look when you have a moment? Happy to make any changes if needed.

Thanks!

This speedy PR is much appreciated, TY! So, it looks good to me and looks like it would exactly address the issue I found. I note that Github Copilot had some comments. One of them, regarding quoting, seemed applicable. The other (Tee pipeline) seemed out of scope for your change). I think your change would not introduce any new problems and would solve the problem I happened to find.