Storage: Read desired mode from config instead of feature flags (#88353)

* Read desired mode from config
* Update playlist integration tests
* Add mode 1 playlist integration tests
* Add mode 0 dual writing to playlist integration tests
* Add documentation for the different dual writing modes

pkg/services/apiserver/aggregator/aggregator.go

@@ -47,6 +47,7 @@ import (
 	"k8s.io/kube-aggregator/pkg/controllers/autoregister"
 
 	"github.com/grafana/grafana/pkg/apiserver/builder"
+	grafanarest "github.com/grafana/grafana/pkg/apiserver/rest"
 	servicev0alpha1applyconfiguration "github.com/grafana/grafana/pkg/generated/applyconfiguration/service/v0alpha1"
 	serviceclientset "github.com/grafana/grafana/pkg/generated/clientset/versioned"
 	informersv0alpha1 "github.com/grafana/grafana/pkg/generated/informers/externalversions"
@@ -284,7 +285,7 @@ func CreateAggregatorServer(config *Config, delegateAPIServer genericapiserver.D
 	})
 
 	for _, b := range config.Builders {
-		serviceAPIGroupInfo, err := b.GetAPIGroupInfo(aggregatorscheme.Scheme, aggregatorscheme.Codecs, aggregatorConfig.GenericConfig.RESTOptionsGetter, false)
+		serviceAPIGroupInfo, err := b.GetAPIGroupInfo(aggregatorscheme.Scheme, aggregatorscheme.Codecs, aggregatorConfig.GenericConfig.RESTOptionsGetter, grafanarest.Mode0)
 		if err != nil {
 			return nil, err
 		}

pkg/services/apiserver/config.go

@@ -6,6 +6,8 @@ import (
 	"path/filepath"
 	"strconv"
 
+	playlist "github.com/grafana/grafana/pkg/apis/playlist/v0alpha1"
+	grafanarest "github.com/grafana/grafana/pkg/apiserver/rest"
 	"github.com/grafana/grafana/pkg/services/apiserver/options"
 	"github.com/grafana/grafana/pkg/services/featuremgmt"
 	"github.com/grafana/grafana/pkg/setting"
@@ -33,6 +35,7 @@ func applyGrafanaConfig(cfg *setting.Cfg, features featuremgmt.FeatureToggles, o
 	host := net.JoinHostPort(cfg.HTTPAddr, strconv.Itoa(port))
 
 	apiserverCfg := cfg.SectionWithEnvOverrides("grafana-apiserver")
+	unifiedStorageModeCfg := cfg.SectionWithEnvOverrides("unified_storage_mode")
 
 	o.RecommendedOptions.Etcd.StorageConfig.Transport.ServerList = apiserverCfg.Key("etcd_servers").Strings(",")
 
@@ -53,6 +56,9 @@ func applyGrafanaConfig(cfg *setting.Cfg, features featuremgmt.FeatureToggles, o
 	o.StorageOptions.StorageType = options.StorageType(apiserverCfg.Key("storage_type").MustString(string(options.StorageTypeLegacy)))
 	o.StorageOptions.DataPath = apiserverCfg.Key("storage_path").MustString(filepath.Join(cfg.DataPath, "grafana-apiserver"))
 	o.StorageOptions.Address = apiserverCfg.Key("address").MustString(o.StorageOptions.Address)
+	o.StorageOptions.DualWriterDesiredModes = map[string]grafanarest.DualWriterMode{
+		playlist.GROUPRESOURCE: grafanarest.DualWriterMode(unifiedStorageModeCfg.Key(playlist.GROUPRESOURCE).MustInt(0)),
+	}
 	o.ExtraOptions.DevMode = features.IsEnabledGlobally(featuremgmt.FlagGrafanaAPIServerEnsureKubectlAccess)
 	o.ExtraOptions.ExternalAddress = host
 	o.ExtraOptions.APIURL = apiURL

pkg/services/apiserver/options/storage.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"net"
 
+	grafanarest "github.com/grafana/grafana/pkg/apiserver/rest"
 	"github.com/spf13/pflag"
 	genericapiserver "k8s.io/apiserver/pkg/server"
 	"k8s.io/apiserver/pkg/server/options"
@@ -20,9 +21,10 @@ const (
 )
 
 type StorageOptions struct {
-	StorageType StorageType
-	DataPath    string
-	Address     string
+	StorageType            StorageType
+	DataPath               string
+	Address                string
+	DualWriterDesiredModes map[string]grafanarest.DualWriterMode
 }
 
 func NewStorageOptions() *StorageOptions {

pkg/services/apiserver/service.go

@@ -308,13 +308,8 @@ func (s *service) start(ctx context.Context) error {
 		return err
 	}
 
-	// dual writing is only enabled when the storage type is not legacy.
-	// this is needed to support setting a default RESTOptionsGetter for new APIs that don't
-	// support the legacy storage type.
-	dualWriteEnabled := o.StorageOptions.StorageType != grafanaapiserveroptions.StorageTypeLegacy
-
 	// Install the API group+version
-	err = builder.InstallAPIs(Scheme, Codecs, server, serverConfig.RESTOptionsGetter, builders, dualWriteEnabled)
+	err = builder.InstallAPIs(Scheme, Codecs, server, serverConfig.RESTOptionsGetter, builders, o.StorageOptions)
 	if err != nil {
 		return err
 	}

pkg/services/apiserver/standalone/options/options.go

@@ -16,6 +16,7 @@ type Options struct {
 	TracingOptions     *TracingOptions
 	MetricsOptions     *MetricsOptions
 	ServerRunOptions   *genericoptions.ServerRunOptions
+	StorageOptions     *options.StorageOptions
 }
 
 func New(logger log.Logger, codec runtime.Codec) *Options {
@@ -26,6 +27,7 @@ func New(logger log.Logger, codec runtime.Codec) *Options {
 		TracingOptions:     NewTracingOptions(logger),
 		MetricsOptions:     NewMetrcicsOptions(logger),
 		ServerRunOptions:   genericoptions.NewServerRunOptions(),
+		StorageOptions:     options.NewStorageOptions(),
 	}
 }