scripts: Verify that we are not using restricted packages

It checks that we are not directly importing 'sync/atomic'.

Signed-off-by: Javier Palomo <javier.palomo.almena@gmail.com>

Makefile.common

@@ -118,7 +118,7 @@ endif
 %: common-% ;
 
 .PHONY: common-all
-common-all: precheck style check_license lint unused build test
+common-all: precheck restricted_imports style check_license lint unused build test
 
 .PHONY: common-style
 common-style:
@@ -270,6 +270,11 @@ proto:
 	@echo ">> generating code from proto files"
 	@./scripts/genproto.sh
 
+.PHONY: common-restricted_imports
+common-restricted_imports:
+	@echo ">> verifying that we are not using restricted packages"
+	@./scripts/check_restricted_imports.sh
+
 ifdef GOLANGCI_LINT
 $(GOLANGCI_LINT):
 	mkdir -p $(FIRST_GOPATH)/bin

scripts/check_restricted_imports.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+#
+# Checks that restricted packages are not being imported.
+# Run from repository root.
+#set -e
+set -u
+
+if ! [[ "$0" =~ "scripts/check_restricted_imports.sh" ]]; then
+	echo "must be run from repository root"
+	exit 255
+fi
+
+exit_status=0
+
+packages=(
+  "sync/atomic"
+)
+for package in "${packages[@]}"
+do
+  # Grep exits with 0 if there is at least one match
+  if output=$(grep -nir "${package}" --exclude-dir=vendor --exclude-dir=scripts ./*); then
+    exit_status=1
+    echo "Restricted package '${package}' is being used in the following files:"
+    echo "${output}"
+  fi
+done
+exit ${exit_status}