new(Makefile): add new targets to the Makefile

* fmt target: make sure that all files are formatted, have the license
  header (if not adds it), checks that the package imports are in order
  and that go mod and sum are tidied.

* lint target: runs golangci-lint against the modified files. Handy
  to check the modified code before pushing it.

Signed-off-by: Aldo Lacuku <[email protected]>

Author: alacuku

Makefile

@@ -1,4 +1,10 @@
 SHELL=/bin/bash -o pipefail
+# Get the currently used golang install path (in GOPATH/bin, unless GOBIN is set)
+ifeq (,$(shell go env GOBIN))
+GOBIN=$(shell go env GOPATH)/bin
+else
+GOBIN=$(shell go env GOBIN)
+endif
 
 GO ?= go
 
@@ -12,4 +18,41 @@ falcoctl:
 .PHONY: test
 test:
 	$(GO) vet ./...
-	$(GO) test ${TEST_FLAGS} ./...
+	$(GO) test ${TEST_FLAGS} ./...
+
+# Install gci if not available
+gci:
+ifeq (, $(shell which gci))
+	@go install github.com/daixiang0/[email protected]
+GCI=$(GOBIN)/gci
+else
+GCI=$(shell which gci)
+endif
+
+# Install addlicense if not available
+addlicense:
+ifeq (, $(shell which addlicense))
+	@go install github.com/google/[email protected]
+ADDLICENSE=$(GOBIN)/addlicense
+else
+ADDLICENSE=$(shell which addlicense)
+endif
+
+# Run go fmt against code and add the licence header
+fmt: gci addlicense
+	go mod tidy
+	go fmt ./...
+	find . -type f -name '*.go' -a -exec $(GCI) -local github.com/falcosecurity/falcoctl -w {} \;
+	find . -type f -name '*.go' -exec $(ADDLICENSE) -l apache -c "The Falco Authors" -y "$(shell date +%Y)" {} \;
+
+# Install golangci-lint if not available
+golangci-lint:
+ifeq (, $(shell which golangci-lint))
+	@go install github.com/golangci/golangci-lint/cmd/[email protected]
+GOLANGCILINT=$(GOBIN)/golangci-lint
+else
+GOLANGCILINT=$(shell which golangci-lint)
+endif
+
+lint: golangci-lint
+	$(GOLANGCILINT) run --new