⚡ Cross-compile go install tools to eliminate QEMU build hang ⚡

The arm64 build was stuck for 12+ hours compiling gopls, dlv, and other
Go tools from source under QEMU user-mode emulation. QEMU makes Go
compilation 20-50× slower than native; gopls alone can take hours.
Fix: add a --platform=$BUILDPLATFORM go-tools stage in the Dockerfile that
cross-compiles all go install tools natively on amd64 using Go's built-in
cross-compilation (GOOS=linux GOARCH=$TARGETARCH). The binaries are then
COPYed into the main build stage before 05-custom.sh runs. No QEMU is
involved for any compilation step.
- Dockerfile: add go-tools stage using --platform=$BUILDPLATFORM with golang:alpine;
cross-compiles goimports, stringer, gopls, govulncheck, dlv, gops, benchstat,
wire, mockgen, protoc-gen-go, protoc-gen-go-grpc; COPY /go/bin/ → /usr/local/bin/
before the 05-custom.sh RUN layer
- rootfs/root/docker/setup/05-custom.sh: remove all go install commands (11 tools
now provided by the Dockerfile stage); keep go clean -modcache/-cache cleanup

Dockerfile
rootfs/root/docker/setup/05-custom.sh

Dockerfile

@@ -29,6 +29,26 @@ ARG DISTRO_VERSION="${IMAGE_VERSION}"
 ARG BUILD_VERSION="${BUILD_DATE}"
 
 FROM tianon/gosu:latest AS gosu
+
+# Build Go tools natively on the host platform using Go's cross-compilation.
+# This avoids QEMU emulation for arm64 and reduces compile time from hours to minutes.
+FROM --platform=$BUILDPLATFORM golang:alpine AS go-tools
+ARG TARGETOS=linux
+ARG TARGETARCH
+ENV CGO_ENABLED=0
+RUN GOOS=${TARGETOS} GOARCH=${TARGETARCH} go install \
+    golang.org/x/tools/cmd/goimports@latest \
+    golang.org/x/tools/cmd/stringer@latest \
+    golang.org/x/tools/gopls@latest \
+    golang.org/x/vuln/cmd/govulncheck@latest \
+    github.com/go-delve/delve/cmd/dlv@latest \
+    github.com/google/gops@latest \
+    golang.org/x/perf/cmd/benchstat@latest \
+    github.com/google/wire/cmd/wire@latest \
+    go.uber.org/mock/mockgen@latest \
+    google.golang.org/protobuf/cmd/protoc-gen-go@latest \
+    google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest
+
 FROM ${PULL_URL}:${DISTRO_VERSION} AS build
 ARG TZ
 ARG USER
@@ -159,6 +179,8 @@ RUN echo "Custom Applications"; \
   $SHELL_OPTS; \
 echo ""
 
+COPY --from=go-tools /go/bin/ /usr/local/bin/
+
 RUN echo "Running custom commands"; \
   if [ -f "/root/docker/setup/05-custom.sh" ];then echo "Running the custom script";/root/docker/setup/05-custom.sh||{ echo "Failed to execute /root/docker/setup/05-custom.sh" && exit 10; };echo "Done running the custom script";fi; \
   echo ""

rootfs/root/docker/setup/05-custom.sh

@@ -191,45 +191,10 @@ _install_bin \
   "https://github.com/pressly/goose/releases/download/${_GOOSE_VER}/goose_linux_${_ARCH_GLIBC}" \
   "goose"
 
-# - - - - - - - - - - - - - - - - - - - - - - - - -
-# go install for tools without standalone release binaries
-
-echo "Installing Go tooling via go install"
-
-# Import organiser — superset of gofmt that also manages import groups
-go install golang.org/x/tools/cmd/goimports@latest
-
-# Generate String() methods for iota-based types
-go install golang.org/x/tools/cmd/stringer@latest
-
-# Official Go language server (no binary releases; must compile)
-go install golang.org/x/tools/gopls@latest
-
-# Vulnerability scanner against the Go vulnerability database
-go install golang.org/x/vuln/cmd/govulncheck@latest
-
-# Source-level debugger
-go install github.com/go-delve/delve/cmd/dlv@latest
-
-# Live process diagnostics: list Go processes, dump stacks, force GC
-go install github.com/google/gops@latest
-
-# Benchmark comparison — statistically sound diff of pprof benchmark runs
-go install golang.org/x/perf/cmd/benchstat@latest
-
-# Compile-time dependency injection code generator
-go install github.com/google/wire/cmd/wire@latest
-
-# Mock generator for interfaces (Uber fork of golang/mock)
-go install go.uber.org/mock/mockgen@latest
-
-# protobuf Go code generator
-go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
-
-# gRPC Go code generator
-go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest
-
-echo "Go tooling installed"
+# go install tools (goimports, stringer, gopls, govulncheck, dlv, gops, benchstat,
+# wire, mockgen, protoc-gen-go, protoc-gen-go-grpc) are cross-compiled natively on
+# the build platform in the Dockerfile go-tools stage and copied to /usr/local/bin
+# before this script runs — no QEMU-emulated compilation needed here.
 
 # Strip the module download cache and ephemeral build cache from this layer
 go clean -modcache