Adding initial version of Kubernetes backend (#552)

Co-authored-by: laszlocph <laszlo@laszlo.cloud>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Rynoxx <rynoxx@grid-servers.net>

pipeline/backend/kubernetes/service.go

@@ -0,0 +1,38 @@
+package kubernetes
+
+import (
+	"fmt"
+	"strconv"
+
+	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/util/intstr"
+)
+
+func Service(namespace, name, podName string, ports []string) (*v1.Service, error) {
+	var svcPorts []v1.ServicePort
+	for _, p := range ports {
+		i, err := strconv.Atoi(p)
+		if err != nil {
+			return nil, fmt.Errorf("Could not parse service port %s as integer", p)
+		}
+		svcPorts = append(svcPorts, v1.ServicePort{
+			Port:       int32(i),
+			TargetPort: intstr.IntOrString{IntVal: int32(i)},
+		})
+	}
+
+	return &v1.Service{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      dnsName(name),
+			Namespace: namespace,
+		},
+		Spec: v1.ServiceSpec{
+			Type: v1.ServiceTypeClusterIP,
+			Selector: map[string]string{
+				"step": podName,
+			},
+			Ports: svcPorts,
+		},
+	}, nil
+}