create-void-go.sh

#!/bin/sh

set -u

if [ "$(id -u)" = "0" ]; then
    echo "You really don't need to run this as root."
    exit 1
fi
if [ "$(lsb_release -cs)" != "void" ]; then
    echo "This doesn't look like a Void Linux system?"
    lsb_release -a
    exit 1
fi

# Some settings.
repo="https://alpha.de.repo.voidlinux.org/current"  # GNU libc; add /musl for musl libc.
cache="/tmp/void-go-cache"                          # xbps cache dir.
img="$(readlink -f ./go.tar)"                       # Image archive to create.
root="/tmp/void-go"                                 # Directory to install Void to.
                                                    # Can be removed afterwards, but kept for manual frobbing.

# Bootstrap xbps.
mkdir -p "$root/var/db/xbps/keys"
cp "/var/db/xbps/keys/"*.plist "$root/var/db/xbps/keys/"
xbps-install -y -c "$cache" -r "$root" -R "$repo" -S

# A very minimal base; we don't need a lot of stuff in base-minimal. This ~45M.
xbps-install -y -c "$cache" -r "$root" -R "$repo" base-files glibc busybox-static ca-certificates
(
	cd "$root/bin"
	for t in $(./busybox.static --list); do [ -h $t ] || ln -s busybox.static $t; done
)

# We want Go and gcc (required for cgo and race detector).
xbps-install -y -c "$cache" -r "$root" -R "$repo" go gcc  # ~560M

# Point Go cache to the right directory.
# go env -w AR=x
echo 'GOCACHE=/cache/go-build'  >  "$root/root/.config/go/env"
echo 'GOMODCACHE=/cache/go-mod' >> "$root/root/.config/go/env"

# Remove xbps cache, and some other files we (probably) don't need.
# This also removes C++ and ADA support from gcc.
rm -r \
	"$root/var/cache/xbps"  \
	"$root/var/db/xbps/"*"/x86_64-repodata" \
	"$root/usr/share/man"   \
	"$root/usr/share/info"  \
	"$root/usr/share/go/"   \
	"$root/usr/bin/"*c++*   \
	"$root/usr/bin/"*g++*   \
	"$root/usr/include/c++" \
	"$root/usr/lib/gcc/"*/?.?/cc1plus \
	"$root/usr/lib/gcc/"*/?.?/gnat1

# Strip binaries and libraries to reduce the size a bit.
find "$root" -executable -exec strip {} \+ >/dev/null 2>&1

# Create the image archive.
(cd "$root" && tar cf "$img" .)
echo "Done; created:"
(cd / && ls -lh "$img")

# End result: ~480M