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, 3 insertions, 2 deletions

diff --git a/main.go b/main.go
index 010fbbdd..75578913 100644
--- a/main.go
+++ b/main.go
@@ -17,6 +17,7 @@ import (
 
 	"gitlab.com/gitlab-org/gitlab-pages/internal/host"
 	"gitlab.com/gitlab-org/gitlab-pages/internal/logging"
+	"gitlab.com/gitlab-org/gitlab-pages/internal/request"
 	"gitlab.com/gitlab-org/gitlab-pages/internal/tlsconfig"
 	"gitlab.com/gitlab-org/gitlab-pages/internal/validateargs"
 	"gitlab.com/gitlab-org/gitlab-pages/metrics"
@@ -123,8 +124,8 @@ func setArtifactsServer(artifactsServer string, artifactsServerTimeout int, conf
 	if err != nil {
 		log.Fatal(err)
 	}
-	// url.Parse ensures that the Scheme arttribute is always lower case.
-	if u.Scheme != "http" && u.Scheme != "https" {
+	// url.Parse ensures that the Scheme attribute is always lower case.
+	if u.Scheme != request.SchemeHTTP && u.Scheme != request.SchemeHTTPS {
 		errortracking.Capture(err)
 		log.Fatal(errArtifactSchemaUnsupported)
 	}