Add make-jenkins filter to find Makefiles with jenkins target

Signed-off-by: Knut Ahlers <knut@ahlers.me>

.gitignore

@@ -0,0 +1 @@
+repo-template

filters.go

@@ -2,7 +2,9 @@ package main
 
 import (
 	"context"
+	"strings"
 
+	"github.com/Luzifer/go_helpers/str"
 	"github.com/google/go-github/github"
 	log "github.com/sirupsen/logrus"
 )
@@ -11,8 +13,9 @@ type filterFunc func(*github.Repository) bool
 
 var filters = map[string]filterFunc{
 	"archived":     filterArchived,
-	"fork":       filterFork,
 	"dockerfile":   filterDockerfile,
+	"fork":         filterFork,
+	"make-jenkins": filterMakeJenkins,
 	"public":       filterPublic,
 }
 
@@ -34,4 +37,29 @@ func filterDockerfile(repo *github.Repository) bool {
 }
 
 func filterFork(repo *github.Repository) bool { return repo.Fork != nil && *repo.Fork }
+
+func filterMakeJenkins(repo *github.Repository) bool {
+	ctx := context.Background()
+	fc, _, resp, err := client.Repositories.GetContents(ctx, *repo.Owner.Login, *repo.Name, "Makefile", nil)
+	if err != nil {
+		if resp.StatusCode == 404 {
+			return false
+		}
+
+		log.WithError(err).Error("Error while looking for Dockerfile")
+		return false
+	}
+
+	if fc.Content == nil {
+		log.Error("File content had no content")
+		return false
+	}
+
+	if str.StringInSlice("jenkins:", strings.Split(*fc.Content, "\n")) {
+		return true
+	}
+
+	return false
+}
+
 func filterPublic(repo *github.Repository) bool { return repo.Private != nil && !*repo.Private }