K8s: Set version info in response (#78083)

Co-authored-by: Jeff Levin <jeff@levinology.com>

pkg/services/grafana-apiserver/service.go

@@ -6,14 +6,20 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"path"
+	goruntime "runtime"
+	"runtime/debug"
 	"strconv"
+	"strings"
+	"time"
 
 	"github.com/go-logr/logr"
 	"github.com/grafana/dskit/services"
+	"golang.org/x/mod/semver"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/runtime/serializer"
+	"k8s.io/apimachinery/pkg/version"
 	"k8s.io/apiserver/pkg/authorization/authorizer"
 	openapinamer "k8s.io/apiserver/pkg/endpoints/openapi"
 	"k8s.io/apiserver/pkg/endpoints/responsewriter"
@@ -261,6 +267,7 @@ func (s *service) start(ctx context.Context) error {
 	}
 
 	serverConfig.Authorization.Authorizer = s.authorizer
+	serverConfig.TracerProvider = s.tracing.GetTracerProvider()
 
 	// Add OpenAPI specs for each group+version
 	defsGetter := getOpenAPIDefinitions(builders)
@@ -275,6 +282,10 @@ func (s *service) start(ctx context.Context) error {
 	// Add the custom routes to service discovery
 	serverConfig.OpenAPIV3Config.PostProcessSpec3 = getOpenAPIPostProcessor(builders)
 
+	// Set the swagger build versions
+	serverConfig.OpenAPIConfig.Info.Version = setting.BuildVersion
+	serverConfig.OpenAPIV3Config.Info.Version = setting.BuildVersion
+
 	serverConfig.SkipOpenAPIInstallation = false
 	serverConfig.BuildHandlerChainFunc = func(delegateHandler http.Handler, c *genericapiserver.Config) http.Handler {
 		// Call DefaultBuildHandlerChain on the main entrypoint http.Handler
@@ -290,7 +301,22 @@ func (s *service) start(ctx context.Context) error {
 		return genericapiserver.DefaultBuildHandlerChain(requestHandler, c)
 	}
 
-	serverConfig.TracerProvider = s.tracing.GetTracerProvider()
+	k8sVersion, err := getK8sApiserverVersion()
+	if err != nil {
+		return err
+	}
+	before, after, _ := strings.Cut(setting.BuildVersion, ".")
+	serverConfig.Version = &version.Info{
+		Major:        before,
+		Minor:        after,
+		GoVersion:    goruntime.Version(),
+		Platform:     fmt.Sprintf("%s/%s", goruntime.GOOS, goruntime.GOARCH),
+		Compiler:     goruntime.Compiler,
+		GitTreeState: setting.BuildBranch,
+		GitCommit:    setting.BuildCommit,
+		BuildDate:    time.Unix(setting.BuildStamp, 0).UTC().Format(time.DateTime),
+		GitVersion:   k8sVersion,
+	}
 
 	// Create the server
 	server, err := serverConfig.Complete().New("grafana-apiserver", genericapiserver.NewEmptyDelegate())
@@ -403,3 +429,29 @@ type roundTripperFunc struct {
 func (f *roundTripperFunc) RoundTrip(req *http.Request) (*http.Response, error) {
 	return f.fn(req)
 }
+
+// find the k8s version according to build info
+func getK8sApiserverVersion() (string, error) {
+	bi, ok := debug.ReadBuildInfo()
+	if !ok {
+		return "", fmt.Errorf("debug.ReadBuildInfo() failed")
+	}
+
+	for _, dep := range bi.Deps {
+		if dep.Path == "k8s.io/apiserver" {
+			if !semver.IsValid(dep.Version) {
+				return "", fmt.Errorf("invalid semantic version for k8s.io/apiserver")
+			}
+			// v0 => v1
+			majorVersion := strings.TrimPrefix(semver.Major(dep.Version), "v")
+			majorInt, err := strconv.Atoi(majorVersion)
+			if err != nil {
+				return "", fmt.Errorf("could not convert majorVersion to int. majorVersion: %s", majorVersion)
+			}
+			newMajor := fmt.Sprintf("v%d", majorInt+1)
+			return strings.Replace(dep.Version, semver.Major(dep.Version), newMajor, 1), nil
+		}
+	}
+
+	return "", fmt.Errorf("could not find k8s.io/apiserver in build info")
+}