From 0bc5e90c3ad77920afeb21e322bb5acfe1feb47a Mon Sep 17 00:00:00 2001
From: Gabe Cook <gabe565@gmail.com>
Date: Sat, 7 Oct 2023 02:54:31 -0500
Subject: [PATCH] fix: Fix job pod label selector on Kubernetes <v1.27

---
 internal/kubernetes/client.go  |  7 +++++++
 internal/kubernetes/version.go | 33 +++++++++++++++++++++++++++++++++
 internal/util/cmd_setup.go     | 17 +++++++++++++++--
 3 files changed, 55 insertions(+), 2 deletions(-)
 create mode 100644 internal/kubernetes/version.go

diff --git a/internal/kubernetes/client.go b/internal/kubernetes/client.go
index d974b863..86669488 100644
--- a/internal/kubernetes/client.go
+++ b/internal/kubernetes/client.go
@@ -4,6 +4,7 @@ import (
 	"path/filepath"
 
 	"github.com/spf13/cobra"
+	"k8s.io/client-go/discovery"
 	"k8s.io/client-go/kubernetes"
 	v1 "k8s.io/client-go/kubernetes/typed/core/v1"
 	"k8s.io/client-go/rest"
@@ -13,6 +14,7 @@ import (
 type KubeClient struct {
 	ClientSet    kubernetes.Interface
 	ClientConfig *rest.Config
+	Discovery    *discovery.DiscoveryClient
 	Namespace    string
 }
 
@@ -64,6 +66,11 @@ func NewClient(kubeconfig, context, namespace string) (config KubeClient, err er
 		return config, err
 	}
 
+	config.Discovery, err = discovery.NewDiscoveryClientForConfig(config.ClientConfig)
+	if err != nil {
+		return config, err
+	}
+
 	return config, err
 }
 
diff --git a/internal/kubernetes/version.go b/internal/kubernetes/version.go
new file mode 100644
index 00000000..2fd7c173
--- /dev/null
+++ b/internal/kubernetes/version.go
@@ -0,0 +1,33 @@
+package kubernetes
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+func (c *KubeClient) MinServerVersion(wantMajor, wantMinor int) (bool, error) {
+	serverVersion, err := c.Discovery.ServerVersion()
+	if err != nil {
+		return false, err
+	}
+
+	vers := strings.TrimPrefix(serverVersion.GitVersion, "v")
+	majorStr, minorStr, found := strings.Cut(vers, ".")
+	if !found {
+		return false, fmt.Errorf("invalid version: %s", serverVersion.GitVersion)
+	}
+	minorStr, _, _ = strings.Cut(minorStr, ".")
+
+	major, err := strconv.Atoi(majorStr)
+	if err != nil {
+		return false, err
+	}
+
+	minor, err := strconv.Atoi(minorStr)
+	if err != nil {
+		return false, err
+	}
+
+	return wantMajor <= major && wantMinor <= minor, nil
+}
diff --git a/internal/util/cmd_setup.go b/internal/util/cmd_setup.go
index 63880830..2c4d120b 100644
--- a/internal/util/cmd_setup.go
+++ b/internal/util/cmd_setup.go
@@ -288,7 +288,7 @@ func watchJobPod(cmd *cobra.Command, conf *config.Global) error {
 	defer cancel()
 
 	watch, err := conf.Client.ClientSet.CoreV1().Pods(conf.Namespace).Watch(ctx, metav1.ListOptions{
-		LabelSelector: "batch.kubernetes.io/controller-uid=" + string(conf.Job.ObjectMeta.UID),
+		LabelSelector: jobPodLabelSelector(conf, conf.Job),
 	})
 	if err != nil {
 		return pollJobPod(ctx, conf)
@@ -324,7 +324,7 @@ func pollJobPod(ctx context.Context, conf *config.Global) error {
 	return wait.PollUntilContextCancel(
 		ctx, time.Second, true, func(ctx context.Context) (done bool, err error) {
 			list, err := conf.Client.ClientSet.CoreV1().Pods(conf.Namespace).List(ctx, metav1.ListOptions{
-				LabelSelector: "batch.kubernetes.io/controller-uid=" + string(conf.Job.ObjectMeta.UID),
+				LabelSelector: jobPodLabelSelector(conf, conf.Job),
 			})
 			if err != nil {
 				return false, err
@@ -349,3 +349,16 @@ func pollJobPod(ctx context.Context, conf *config.Global) error {
 		},
 	)
 }
+
+func jobPodLabelSelector(conf *config.Global, job *batchv1.Job) string {
+	useNewLabel, err := conf.Client.MinServerVersion(1, 27)
+	if err != nil {
+		log.WithError(err).Warn("failed to query server version; assuming v1.27+")
+		useNewLabel = true
+	}
+
+	if useNewLabel {
+		return "batch.kubernetes.io/controller-uid=" + string(job.ObjectMeta.UID)
+	}
+	return "controller-uid=" + string(job.ObjectMeta.UID)
+}