Add .golangci.yml linter configuration

As part of https://gitlab.com/gitlab-org/gitlab-pages/-/issues/385
we have introduced the use of a custom `.golangci.yml` file with some
custom rules for linting.

This replaces the need of downloading and using `golint`, `gofmt`
`go vet` and `gocyclo` manually. We take advantage of the custom
`golangci-lint` docker image as stated in the [Automatic lintinb]
(https://docs.gitlab.com/ee/development/go_guide/#automatic-linting)
section of the Go standards and style guidelines.

This iteration enables a subset of linters, with the remaining
of them enabled on a separate MR as described in the issue above.

The main changes introduced by this linter include:

- gosec: potential hardcoded credentials
- goconst: DRY by declaring and using constants
- gosimple: reduce statements complexity and improve return statements

1 files changed, 6 insertions, 13 deletions

diff --git a/Makefile.util.mk b/Makefile.util.mk
index 412b7655..dfc2c8fd 100644
--- a/Makefile.util.mk
+++ b/Makefile.util.mk
@@ -1,18 +1,11 @@
-.PHONY: verify fmt vet lint complexity test cover list
+GOLANGCI_LINT_IMAGE := registry.gitlab.com/gitlab-org/gitlab-build-images:golangci-lint-alpine
 
-verify: list fmt vet lint complexity
+.PHONY: lint test race acceptance bench cover list deps-check deps-download
 
-fmt: bin/goimports .GOPATH/.ok
-	$Q @_support/validate-formatting.sh $(allfiles)
-
-vet: .GOPATH/.ok
-	$Q go vet $(allpackages)
-
-lint: bin/golint
-	$Q ./bin/golint $(allpackages) | tee | ( ! grep -v "^$$" )
-
-complexity: .GOPATH/.ok bin/gocyclo
-	$Q ./bin/gocyclo -over 9 $(allfiles)
+lint: deps-download
+	docker run -v $(PWD):/app -w /app $(GOLANGCI_LINT_IMAGE) \
+	sh -c "golangci-lint run --out-format code-climate | tee gl-code-quality-report.json | jq -r '.[] | \"\(.location.path):\(.location.lines.begin) \(.description)\"'"
+#		sh -c "golangci-lint run  $(if $V,-v)"
 
 test: .GOPATH/.ok gitlab-pages
 	go test $(if $V,-v) $(allpackages)