executors/kubernetes: map service name as pod HostAlias

executors/kubernetes/executor_kubernetes.go

@@ -14,6 +14,7 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/kubernetes/scheme"
+
 	// Register all available authentication methods
 	_ "k8s.io/client-go/plugin/pkg/client/auth"
 	restclient "k8s.io/client-go/rest"
@@ -437,9 +438,18 @@ func (s *executor) setupCredentials() error {
 
 func (s *executor) setupBuildPod() error {
 	services := make([]api.Container, len(s.options.Services))
+	servicesHostAlias := api.HostAlias{IP: "127.0.0.1"}
 	for i, service := range s.options.Services {
 		resolvedImage := s.Build.GetAllVariables().ExpandValue(service.Name)
 		services[i] = s.buildContainer(fmt.Sprintf("svc-%d", i), resolvedImage, service, s.serviceRequests, s.serviceLimits)
+
+		_, _, _, aliases := common.SplitServiceAndVersion(service.Name)
+		for _, a := range aliases {
+			servicesHostAlias.Hostnames = append(servicesHostAlias.Hostnames, a)
+		}
+		if service.Alias != "" {
+			servicesHostAlias.Hostnames = append(servicesHostAlias.Hostnames, service.Alias)
+		}
 	}
 
 	labels := make(map[string]string)
@@ -484,6 +494,7 @@ func (s *executor) setupBuildPod() error {
 			}, services...),
 			TerminationGracePeriodSeconds: &s.Config.Kubernetes.TerminationGracePeriodSeconds,
 			ImagePullSecrets:              imagePullSecrets,
+			HostAliases:                   []api.HostAlias{servicesHostAlias},
 		},
 	})
 

executors/kubernetes/executor_kubernetes_test.go

@@ -1316,6 +1316,69 @@ func TestSetupBuildPod(t *testing.T) {
 				assert.Equal(t, []string{"application", "--debug"}, pod.Spec.Containers[3].Args)
 			},
 		},
+		"supports services as host aliases": {
+			RunnerConfig: common.RunnerConfig{
+				RunnerSettings: common.RunnerSettings{
+					Kubernetes: &common.KubernetesConfig{
+						Namespace:   "default",
+						HelperImage: "custom/helper-image",
+					},
+				},
+			},
+			Options: &kubernetesOptions{
+				Image: common.Image{
+					Name:       "test-image",
+					Entrypoint: []string{"/init", "run"},
+				},
+				Services: common.Services{
+					{
+						Name:  "test-service",
+						Alias: "svc-alias",
+					},
+					{
+						Name: "docker:dind",
+					},
+				},
+			},
+			VerifyFn: func(t *testing.T, test setupBuildPodTestDef, pod *api.Pod) {
+				require.Len(t, pod.Spec.Containers, 4)
+
+				expectedHostnames := []string{
+					"test-service",
+					"svc-alias",
+					"docker",
+				}
+				assert.Equal(t, "127.0.0.1", pod.Spec.HostAliases[0].IP)
+				assert.Equal(t, expectedHostnames, pod.Spec.HostAliases[0].Hostnames)
+			},
+		},
+		"supports services as kubernetes host aliases with simple docker image syntax": {
+			RunnerConfig: common.RunnerConfig{
+				RunnerSettings: common.RunnerSettings{
+					Kubernetes: &common.KubernetesConfig{
+						Namespace:   "default",
+						HelperImage: "custom/helper-image",
+					},
+				},
+			},
+			Options: &kubernetesOptions{
+				Image: common.Image{
+					Name:       "test-image",
+					Entrypoint: []string{"/init", "run"},
+				},
+				Services: common.Services{
+					{
+						Name: "docker:dind",
+					},
+				},
+			},
+			VerifyFn: func(t *testing.T, test setupBuildPodTestDef, pod *api.Pod) {
+				require.Len(t, pod.Spec.Containers, 3)
+
+				assert.Equal(t, "127.0.0.1", pod.Spec.HostAliases[0].IP)
+				assert.Equal(t, []string{"docker"}, pod.Spec.HostAliases[0].Hostnames)
+			},
+		},
 		// TODO: Remove the mention of Feature Flag in 12.0, make it the only proper test case.
 		"properly sets command (entrypoint) and args when FF_K8S_USE_ENTRYPOINT_OVER_COMMAND is on": {
 			RunnerConfig: common.RunnerConfig{