chore: parse "boolean" variables

Makes `make WITH_DEBUG=1` work.

Refs #3534.

Signed-off-by: Alexey Palazhchenko <alexey.palazhchenko@gmail.com>

Makefile

@@ -47,16 +47,16 @@ GO_LDFLAGS ?= -s -w \
 	-X $(IMAGES_PKGS).Registry=$(REGISTRY) \
 	-X $(MGMT_HELPERS_PKG).ArtifactsPath=$(ARTIFACTS)
 
-WITH_RACE ?=
-WITH_DEBUG ?=
+WITH_RACE ?= false
+WITH_DEBUG ?= false
 
-ifneq ($(strip $(WITH_RACE)),)
+ifeq ($(shell hack/parsebool.sh $(WITH_RACE); echo $$?), 1)
 CGO_ENABLED = 1
 GO_BUILDFLAGS += -race
 GO_LDFLAGS += -linkmode=external -extldflags '-static'
 endif
 
-ifeq ($(WITH_DEBUG), true)
+ifeq ($(shell hack/parsebool.sh $(WITH_DEBUG); echo $$?), 1)
 GO_BUILDFLAGS += -tags sidero.debug
 endif
 

hack/parsebool.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+# parsebool.sh exits with code:
+#   0 if passed argument is false, FALSE, f, 0, etc
+#   1 if passed argument is true, TRUE, t, 1, etc
+#   2 if passed argument is absent, an empty string or something else
+
+set -e
+
+arg=$(echo $* | tr '[:upper:]' '[:lower:]')
+
+case $arg in
+  false|f|0) exit 0 ;;
+  true|t|1) exit 1 ;;
+  *) exit 2 ;;
+esac