Reintroduce k8s client fallback to cache lookups

cmd/single/start.go

@@ -18,6 +18,7 @@ import (
 	adminScheduler "github.com/flyteorg/flyte/flyteadmin/scheduler"
 	propellerEntrypoint "github.com/flyteorg/flyte/flytepropeller/pkg/controller"
 	propellerConfig "github.com/flyteorg/flyte/flytepropeller/pkg/controller/config"
+	"github.com/flyteorg/flyte/flytepropeller/pkg/controller/executors"
 	"github.com/flyteorg/flyte/flytepropeller/pkg/signals"
 	webhookEntrypoint "github.com/flyteorg/flyte/flytepropeller/pkg/webhook"
 	webhookConfig "github.com/flyteorg/flyte/flytepropeller/pkg/webhook/config"
@@ -33,9 +34,7 @@ import (
 	"github.com/spf13/cobra"
 	"golang.org/x/sync/errgroup"
 	_ "gorm.io/driver/postgres" // Required to import database driver.
-	"k8s.io/client-go/rest"
 	"sigs.k8s.io/controller-runtime/pkg/cache"
-	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/manager"
 	"sigs.k8s.io/controller-runtime/pkg/metrics"
 )
@@ -122,22 +121,8 @@ func startPropeller(ctx context.Context, cfg Propeller) error {
 			SyncPeriod:        &propellerCfg.DownstreamEval.Duration,
 			DefaultNamespaces: namespaceConfigs,
 		},
-		NewCache: func(config *rest.Config, options cache.Options) (cache.Cache, error) {
-			k8sCache, err := cache.New(config, options)
-			if err != nil {
-				return k8sCache, err
-			}
-
-			return otelutils.WrapK8sCache(k8sCache), nil
-		},
-		NewClient: func(config *rest.Config, options client.Options) (client.Client, error) {
-			k8sClient, err := client.New(config, options)
-			if err != nil {
-				return k8sClient, err
-			}
-
-			return otelutils.WrapK8sClient(k8sClient), nil
-		},
+		NewCache: executors.NewCache,
+		NewClient: executors.NewClient,
 		Metrics: metricsserver.Options{
 			// Disable metrics serving
 			BindAddress: "0",

flytepropeller/cmd/controller/cmd/root.go

@@ -12,16 +12,15 @@ import (
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 	"golang.org/x/sync/errgroup"
-	"k8s.io/client-go/rest"
 	"k8s.io/klog"
 	"sigs.k8s.io/controller-runtime/pkg/cache"
-	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/manager"
 	"sigs.k8s.io/controller-runtime/pkg/metrics"
 	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
 
 	"github.com/flyteorg/flyte/flytepropeller/pkg/controller"
 	config2 "github.com/flyteorg/flyte/flytepropeller/pkg/controller/config"
+	"github.com/flyteorg/flyte/flytepropeller/pkg/controller/executors"
 	"github.com/flyteorg/flyte/flytepropeller/pkg/signals"
 	"github.com/flyteorg/flyte/flytestdlib/config"
 	"github.com/flyteorg/flyte/flytestdlib/config/viper"
@@ -144,22 +143,8 @@ func executeRootCmd(baseCtx context.Context, cfg *config2.Config) error {
 			SyncPeriod:        &cfg.DownstreamEval.Duration,
 			DefaultNamespaces: namespaceConfigs,
 		},
-		NewCache: func(config *rest.Config, options cache.Options) (cache.Cache, error) {
-			k8sCache, err := cache.New(config, options)
-			if err != nil {
-				return k8sCache, err
-			}
-
-			return otelutils.WrapK8sCache(k8sCache), nil
-		},
-		NewClient: func(config *rest.Config, options client.Options) (client.Client, error) {
-			k8sClient, err := client.New(config, options)
-			if err != nil {
-				return k8sClient, err
-			}
-
-			return otelutils.WrapK8sClient(k8sClient), nil
-		},
+		NewCache:  executors.NewCache,
+		NewClient: executors.NewClient,
 		Metrics: metricsserver.Options{
 			// Disable metrics serving
 			BindAddress: "0",

flytepropeller/cmd/controller/cmd/webhook.go

@@ -5,9 +5,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"golang.org/x/sync/errgroup"
-	"k8s.io/client-go/rest"
 	"sigs.k8s.io/controller-runtime/pkg/cache"
-	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/manager"
 	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
 	ctrlWebhook "sigs.k8s.io/controller-runtime/pkg/webhook"
@@ -110,9 +108,8 @@ func runWebhook(origContext context.Context, propellerCfg *config.Config, cfg *w
 			SyncPeriod:        &propellerCfg.DownstreamEval.Duration,
 			DefaultNamespaces: namespaceConfigs,
 		},
-		NewClient: func(config *rest.Config, options client.Options) (client.Client, error) {
-			return executors.NewFallbackClientBuilder(webhookScope).Build(nil, config, options)
-		},
+		NewCache:  executors.NewCache,
+		NewClient: executors.NewClient,
 		Metrics: metricsserver.Options{
 			// Disable metrics serving
 			BindAddress: "0",

flytepropeller/pkg/controller/executors/kube.go

@@ -9,6 +9,7 @@
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
 	"github.com/flyteorg/flyte/flytestdlib/fastcheck"
+	"github.com/flyteorg/flyte/flytestdlib/otelutils"
 	"github.com/flyteorg/flyte/flytestdlib/promutils"
 )
 
@@ -23,26 +24,66 @@
 	GetCache() cache.Cache
 }
 
-// ClientBuilder builder is the interface for the client builder.
-type ClientBuilder interface {
-	// Build returns a new client.
-	Build(cache cache.Cache, config *rest.Config, options client.Options) (client.Client, error)
+var NewCache = func(config *rest.Config, options cache.Options) (cache.Cache, error) {
+	k8sCache, err := cache.New(config, options)
+	if err != nil {
+		return k8sCache, err
+	}
+
+	return otelutils.WrapK8sCache(k8sCache), nil
+}
+
+var NewClient = func(config *rest.Config, options client.Options) (client.Client, error) {
+	var reader *fallbackClientReader
+	if options.Cache != nil && options.Cache.Reader != nil {
+		// if caching is enabled we create a fallback reader so we can attempt the client if the cache
+		// reader does not have the object
+		reader = &fallbackClientReader{
+			orderedClients: []client.Reader{options.Cache.Reader},
+		}
+
+		options.Cache.Reader = reader
+	}
+
+	// create the k8s client
+	k8sClient, err := client.New(config, options)
+	if err != nil {
+		return k8sClient, err
+	}
+
+	k8sOtelClient := otelutils.WrapK8sClient(k8sClient)
+	if reader != nil {
+		// once the k8s client is created we set the fallback reader's client to the k8s client
+		reader.orderedClients = append(reader.orderedClients, k8sOtelClient)
+	}
+
+	return k8sOtelClient, nil
 }
 
-type FallbackClientBuilder struct {
-	scope promutils.Scope
+// fallbackClientReader reads from the cache first and if not found then reads from the configured reader, which
+// directly reads from the API
+type fallbackClientReader struct {
+	orderedClients []client.Reader
 }
 
-func (f *FallbackClientBuilder) Build(_ cache.Cache, config *rest.Config, options client.Options) (client.Client, error) {
-	return client.New(config, options)
+func (c fallbackClientReader) Get(ctx context.Context, key client.ObjectKey, out client.Object, opts ...client.GetOption) (err error) {
+	for _, k8sClient := range c.orderedClients {
+		if err = k8sClient.Get(ctx, key, out, opts...); err == nil {
+			return nil
+		}
+	}
+
+	return
 }
 
-// NewFallbackClientBuilder Creates a new k8s client that uses the cached client for reads and falls back to making API
-// calls if it failed. Write calls will always go to raw client directly.
-func NewFallbackClientBuilder(scope promutils.Scope) *FallbackClientBuilder {
-	return &FallbackClientBuilder{
-		scope: scope,
+func (c fallbackClientReader) List(ctx context.Context, list client.ObjectList, opts ...client.ListOption) (err error) {
+	for _, k8sClient := range c.orderedClients {
+		if err = k8sClient.List(ctx, list, opts...); err == nil {
+			return nil
+		}
 	}
+
+	return
 }
 
 type writeThroughCachingWriter struct {