tool/gocross: a tool for building Tailscale binaries

Signed-off-by: David Anderson <danderson@tailscale.com>
2023-02-21 16:07:33 -08:00
parent 0b8f89c79c
commit 860734aed9
12 changed files with 1324 additions and 78 deletions
@@ -0,0 +1,72 @@
+#!/usr/bin/env sh
+# Copyright (c) Tailscale Inc & AUTHORS
+# SPDX-License-Identifier: BSD-3-Clause
+#
+# gocross-wrapper.sh is a wrapper that can be aliased to 'go', which
+# transparently builds gocross using a "bootstrap" Go toolchain, and
+# then invokes gocross.
+
+set -eu
+
+if [ "${CI:-}" = "true" ]; then
+    set -x
+fi
+
+repo_root="$(dirname $0)/../.."
+
+toolchain="$HOME/.cache/tailscale-go"
+
+if [ ! -d "$toolchain" ]; then
+    mkdir -p "$HOME/.cache"
+
+    # We need any Go toolchain to build gocross, but the toolchain also has to
+    # be reasonably recent because we upgrade eagerly and gocross might not
+    # build with Go N-1. So, if we have no cached tailscale toolchain at all,
+    # fetch the initial one in shell. Once gocross is built, it'll manage
+    # updates.
+    read -r REV <$repo_root/go.toolchain.rev
+
+    # This works for linux and darwin, which is sufficient
+    # (we do not build tailscale-go for other targets).
+    HOST_OS=$(uname -s | tr A-Z a-z)
+    HOST_ARCH="$(uname -m)"
+    if [ "$HOST_ARCH" = "aarch64" ]; then
+        # Go uses the name "arm64".
+        HOST_ARCH="arm64"
+    elif [ "$HOST_ARCH" = "x86_64" ]; then
+        # Go uses the name "amd64".
+        HOST_ARCH="amd64"
+    fi
+
+    rm -rf "$toolchain" "$toolchain.extracted"
+    curl -f -L -o "$toolchain.tar.gz" "https://github.com/tailscale/go/releases/download/build-${REV}/${HOST_OS}-${HOST_ARCH}.tar.gz"
+    mkdir -p "$toolchain"
+    (cd "$toolchain" && tar --strip-components=1 -xf "$toolchain.tar.gz")
+    echo "$REV" >"$toolchain.extracted"
+fi
+
+# Binaries run with `gocross run` can reinvoke gocross, resulting in a
+# potentially fancy build that invokes external linkers, might be
+# cross-building for other targets, and so forth. In one hilarious
+# case, cmd/cloner invokes go with GO111MODULE=off at some stage.
+#
+# Anyway, build gocross in a stripped down universe.
+gocross_path="$repo_root/gocross"
+gocross_ok=0
+if [ -x "$gocross_path" ]; then
+	gotver="$($gocross_path gocross-version 2>/dev/null || echo '')"
+	wantver="$(git rev-parse HEAD)"
+	if [ "$gotver" = "$wantver" ]; then
+		gocross_ok=1
+	fi
+fi
+if [ "$gocross_ok" = "0" ]; then
+    (
+        unset GOOS
+        unset GOARCH
+        unset GO111MODULE
+        export CGO_ENABLED=0
+        "$toolchain/bin/go" build -o "$gocross_path" tailscale.com/tool/gocross
+    )
+fi
+exec "$gocross_path" "$@"