From 7aea06fce8386b44b8f5fca68b479f9656b8abc3 Mon Sep 17 00:00:00 2001
From: Simone Gotti <simone.gotti@gmail.com>
Date: Mon, 8 Jul 2019 13:51:31 +0200
Subject: [PATCH] k8s driver: use right node selector on old k8s versions

Before kubernetes 1.14 nodes were labeled with the "beta.kubernetes.io/arch"
label instead of the "kubernetes.io/arch".

Current k8s version (v1.15) labels nodes with both labels but it's
deprecated and will removed in future versions.

At driver start get the current k8s api version and choose the right label to
use as node selector based on it.
---
 internal/services/executor/driver/k8s.go      | 62 ++++++++++++++++---
 internal/services/executor/driver/k8s_test.go | 49 +++++++++++++++
 2 files changed, 104 insertions(+), 7 deletions(-)

diff --git a/internal/services/executor/driver/k8s.go b/internal/services/executor/driver/k8s.go
index 2caa578..dc9344c 100644
--- a/internal/services/executor/driver/k8s.go
+++ b/internal/services/executor/driver/k8s.go
@@ -21,6 +21,8 @@ import (
 	"fmt"
 	"io"
 	"path/filepath"
+	"regexp"
+	"strconv"
 	"strings"
 	"time"
 
@@ -62,6 +64,8 @@ const (
 	renewExecutorLeaseInterval = 10 * time.Second
 	staleExecutorLeaseInterval = 1 * time.Minute
 	informerResyncInterval     = 10 * time.Second
+
+	k8sLabelArchBeta = "beta.kubernetes.io/arch"
 )
 
 type K8sDriver struct {
@@ -77,6 +81,7 @@ type K8sDriver struct {
 	podLister        listerscorev1.PodLister
 	cmLister         listerscorev1.ConfigMapLister
 	leaseLister      coordinationlistersv1.LeaseLister
+	k8sLabelArch     string
 }
 
 type K8sPod struct {
@@ -106,12 +111,29 @@ func NewK8sDriver(logger *zap.Logger, executorID, toolboxPath string) (*K8sDrive
 	}
 
 	d := &K8sDriver{
-		log:         logger.Sugar(),
-		restconfig:  kubecfg,
-		client:      kubecli,
-		toolboxPath: toolboxPath,
-		namespace:   namespace,
-		executorID:  executorID,
+		log:          logger.Sugar(),
+		restconfig:   kubecfg,
+		client:       kubecli,
+		toolboxPath:  toolboxPath,
+		namespace:    namespace,
+		executorID:   executorID,
+		k8sLabelArch: corev1.LabelArchStable,
+	}
+
+	serverVersion, err := d.client.Discovery().ServerVersion()
+	if err != nil {
+		return nil, err
+	}
+	sv, err := parseGitVersion(serverVersion.GitVersion)
+	// if server version parsing fails just warn but ignore it
+	if err != nil {
+		d.log.Warnf("failed to parse k8s server version: %v", err)
+	}
+	if sv != nil {
+		// for k8s version < v1.14.x use old arch label
+		if sv.Major == 1 && sv.Minor < 14 {
+			d.k8sLabelArch = k8sLabelArchBeta
+		}
 	}
 
 	lists, err := d.client.Discovery().ServerPreferredResources()
@@ -399,7 +421,7 @@ func (d *K8sDriver) NewPod(ctx context.Context, podConfig *PodConfig, out io.Wri
 
 	if podConfig.Arch != "" {
 		pod.Spec.NodeSelector = map[string]string{
-			corev1.LabelArchStable: string(podConfig.Arch),
+			d.k8sLabelArch: string(podConfig.Arch),
 		}
 	}
 
@@ -736,3 +758,29 @@ func genEnvVars(env map[string]string) []corev1.EnvVar {
 	}
 	return envVars
 }
+
+type serverVersion struct {
+	Major int
+	Minor int
+}
+
+// k8s version is in this format: v0.0.0(-master+$Format:%h$)
+var gitVersionRegex = regexp.MustCompile("v([0-9]+).([0-9]+).[0-9]+.*")
+
+func parseGitVersion(gitVersion string) (*serverVersion, error) {
+	parsedVersion := gitVersionRegex.FindStringSubmatch(gitVersion)
+	if len(parsedVersion) != 3 {
+		return nil, fmt.Errorf("cannot parse git version %s", gitVersion)
+	}
+	sv := &serverVersion{}
+	var err error
+	sv.Major, err = strconv.Atoi(parsedVersion[1])
+	if err != nil {
+		return nil, err
+	}
+	sv.Minor, err = strconv.Atoi(parsedVersion[2])
+	if err != nil {
+		return nil, err
+	}
+	return sv, nil
+}
diff --git a/internal/services/executor/driver/k8s_test.go b/internal/services/executor/driver/k8s_test.go
index 4073fa2..4b099c9 100644
--- a/internal/services/executor/driver/k8s_test.go
+++ b/internal/services/executor/driver/k8s_test.go
@@ -19,6 +19,7 @@ import (
 	"context"
 	"io/ioutil"
 	"os"
+	"reflect"
 	"testing"
 	"time"
 
@@ -253,3 +254,51 @@ func TestK8sPod(t *testing.T) {
 	})
 
 }
+
+func TestParseGitVersion(t *testing.T) {
+	tests := []struct {
+		gitVersion string
+		out        *serverVersion
+		err        bool
+	}{
+		{
+			gitVersion: "v1.8.0",
+			out:        &serverVersion{Major: 1, Minor: 8},
+		},
+		{
+			gitVersion: "v1.12.0",
+			out:        &serverVersion{Major: 1, Minor: 12},
+		},
+		{
+			gitVersion: "v1.12.20",
+			out:        &serverVersion{Major: 1, Minor: 12},
+		},
+		{
+			gitVersion: "v1.12.8-test.10",
+			out:        &serverVersion{Major: 1, Minor: 12},
+		},
+		{
+			gitVersion: "v1.a",
+			err:        true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run("", func(t *testing.T) {
+			sv, err := parseGitVersion(tt.gitVersion)
+			if tt.err {
+				if err == nil {
+					t.Errorf("expected error, got nil error")
+				}
+				return
+			}
+			if err != nil {
+				t.Errorf("unexpected err: %v", err)
+				return
+			}
+			if !reflect.DeepEqual(sv, tt.out) {
+				t.Errorf("expected %v, got %v", tt.out, sv)
+			}
+		})
+	}
+}