Makefile target to remove generated files (#63)

* Makefile rm's generated files before generating again and does operations relative to Makefile's path.

Makefile

@@ -1,16 +1,19 @@
 # Determine this makefile's path.
 # Be sure to place this BEFORE `include` directives, if any.
 THIS_FILE := $(lastword $(MAKEFILE_LIST))
+THIS_DIR := $(dir $(realpath $(firstword $(MAKEFILE_LIST))))
 
 TMP_DIR := $(shell mktemp -d)
 REPO_PATH := github.com/hashicorp/watchtower
 
+GENERATED_CODE := $(shell  find ${THIS_DIR} -name '*.gen.go' && find ${THIS_DIR} -name '*.pb.go' && find ${THIS_DIR} -name '*.pb.gw.go')
+
 export GEN_BASEPATH := $(shell pwd)
 
 bootstrap:
 	go generate -tags tools tools/tools.go
 
-gen: proto api migrations
+gen: cleangen proto api migrations
 
 api:
 	$(MAKE) --environment-overrides -C api/internal/genapi api
@@ -18,9 +21,12 @@ api:
 migrations:
 	$(MAKE) --environment-overrides -C internal/db/migrations/genmigrations migrations
 
+cleangen:
+	@rm -f ${GENERATED_CODE}
+
 ### oplog requires protoc-gen-go v1.20.0 or later
 # GO111MODULE=on go get -u github.com/golang/protobuf/protoc-gen-go@v1.40
-proto: protolint protobuild cleanup
+proto: protolint protobuild
 
 protolint:
 	@buf check lint
@@ -40,18 +46,16 @@ protobuild:
 		"--plugin_out=logtostderr=true:${TMP_DIR}"
 
 	# Move the generated files from the tmp file subdirectories into the current repo.
-	cp -R ${TMP_DIR}/${REPO_PATH}/* .
+	cp -R ${TMP_DIR}/${REPO_PATH}/* ${THIS_DIR}
 
 	@protoc --proto_path=internal/proto/local --proto_path=internal/proto/third_party --swagger_out=logtostderr=true,disable_default_errors=true,include_package_in_tags=true,fqn_for_swagger_name=true,allow_merge,merge_file_name=controller:internal/gen/. internal/proto/local/controller/api/services/v1/*.proto
 	@protoc-go-inject-tag -input=./internal/oplog/store/oplog.pb.go
 	@protoc-go-inject-tag -input=./internal/oplog/oplog_test/oplog_test.pb.go
 	@protoc-go-inject-tag -input=./internal/iam/store/scope.pb.go
 	@protoc-go-inject-tag -input=./internal/db/db_test/db_test.pb.go
-
-cleanup:
 	@rm -R ${TMP_DIR}
 
 
-.PHONY: api bootstrap cleanup gen migrations proto
+.PHONY: api bootstrap gen migrations proto
 
 .NOTPARALLEL: