Add lint

Author: thombashi

.golangci.yaml

@@ -0,0 +1,6 @@
+run:
+  timeout: 3m
+
+linters:
+  enable:
+    - gofmt

Makefile

@@ -1,10 +1,16 @@
 PRE_COMMIT := pre-commit
+
 JSONNET_VERSION := v0.18.0
+GOLANGCI_VERSION := v1.46.1
 
 .PHONY: fmt
 fmt:
 	@go fmt ./...
 
+.PHONY: lint
+lint:
+	@golangci-lint run ./...
+
 .PHONY: test
 test:
 	@go test -v ./...
@@ -18,3 +24,5 @@ run:
 setup:
 	@go install github.com/google/go-jsonnet/cmd/jsonnet-lint@$(JSONNET_VERSION)
 	@go install github.com/google/go-jsonnet/cmd/jsonnetfmt@$(JSONNET_VERSION)
+
+	@curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(shell go env GOPATH)/bin $(GOLANGCI_VERSION)