From 15b69b014f7ed1f881a40369d806e58c5689d2b5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marco=20Andr=C3=A9=20Dinis?= <marcoandredinis@gmail.com>
Date: Tue, 9 May 2023 14:58:37 +0100
Subject: [PATCH] Makefile: cache `go env` values

Spawning shells is expensive for Makefile targets.
We use the `OS` and `ARCH` variables in a lot of places.
They come from spawning a subshell and then executing `go env GOOS` or
`go env GOARCH`.

So, everytime we need them, we spawn a subshells.
Just parsing the Makefile adds quite some time, even if the target
itself is fast.

This PR caches those values, so that we only need to spawn a subshell
once per execution.

Tests show that running `make print-version` is now much faster:
Using linux: drop from 56s to 0.240s
Using MacOS M1: drop from 291ms to 119ms
YMMV
---
 Makefile | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index b8c28a147402d..39e8609fb6cd9 100644
--- a/Makefile
+++ b/Makefile
@@ -49,8 +49,12 @@ else
 BUILDFLAGS ?= $(ADDFLAGS) -ldflags '-w -s' -trimpath
 endif
 
-OS ?= $(shell go env GOOS)
-ARCH ?= $(shell go env GOARCH)
+GO_ENV_OS := $(shell go env GOOS)
+OS ?= $(GO_ENV_OS)
+
+GO_ENV_ARCH := $(shell go env GOARCH)
+ARCH ?= $(GO_ENV_ARCH)
+
 FIPS ?=
 RELEASE = teleport-$(GITTAG)-$(OS)-$(ARCH)-bin