MM-28859 Add feature flag managment system using split.io and remove viper. (#15954)

* Add feature flag managment system using split.io and remove viper.

* Fixing tests.

* Attempt to fix postgres tests.

* Fix watch filepath for advanced logging.

* Review fixes.

* Some error wrapping.

* Remove unessisary store interface.

* Desanitize SplitKey

* Simplify.

* Review feedback.

* Rename split mlog adatper to split logger.

* fsInner

* Style.

* Restore oldcfg test.

* Downgrading non-actionable feature flag errors to warnings.

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

config/memory.go

@@ -4,9 +4,7 @@
 package config
 
 import (
-	"bytes"
 	"fmt"
-	"io/ioutil"
 
 	"github.com/pkg/errors"
 
@@ -14,9 +12,8 @@ import (
 )
 
 // MemoryStore implements the Store interface. It is meant primarily for testing.
+// Not to be used directly. Only to be used as a backing store for config.Store
 type MemoryStore struct {
-	commonStore
-
 	allowEnvironmentOverrides bool
 	validate                  bool
 	files                     map[string][]byte
@@ -56,24 +53,12 @@ func NewMemoryStoreWithOptions(options *MemoryStoreOptions) (*MemoryStore, error
 		savedConfig:               savedConfig,
 	}
 
-	ms.commonStore.config = &model.Config{}
-	ms.commonStore.config.SetDefaults()
-
-	if err := ms.Load(); err != nil {
-		return nil, err
-	}
-
 	return ms, nil
 }
 
 // Set replaces the current configuration in its entirety.
-func (ms *MemoryStore) Set(newCfg *model.Config) (*model.Config, error) {
-	validate := ms.commonStore.validate
-	if !ms.validate {
-		validate = nil
-	}
-
-	return ms.commonStore.set(newCfg, ms.allowEnvironmentOverrides, validate, ms.persist)
+func (ms *MemoryStore) Set(newCfg *model.Config) error {
+	return ms.persist(newCfg)
 }
 
 // persist copies the active config to the saved config.
@@ -84,28 +69,18 @@ func (ms *MemoryStore) persist(cfg *model.Config) error {
 }
 
 // Load applies environment overrides to the default config as if a re-load had occurred.
-func (ms *MemoryStore) Load() (err error) {
-	var cfgBytes []byte
-	cfgBytes, err = marshalConfig(ms.savedConfig)
+func (ms *MemoryStore) Load() ([]byte, error) {
+	cfgBytes, err := marshalConfig(ms.savedConfig)
 	if err != nil {
-		return errors.Wrap(err, "failed to serialize config")
+		return nil, errors.Wrap(err, "failed to serialize config")
 	}
 
-	f := ioutil.NopCloser(bytes.NewReader(cfgBytes))
+	return cfgBytes, nil
 
-	validate := ms.commonStore.validate
-	if !ms.validate {
-		validate = nil
-	}
-
-	return ms.commonStore.load(f, false, validate, ms.persist)
 }
 
 // GetFile fetches the contents of a previously persisted configuration file.
 func (ms *MemoryStore) GetFile(name string) ([]byte, error) {
-	ms.configLock.RLock()
-	defer ms.configLock.RUnlock()
-
 	data, ok := ms.files[name]
 	if !ok {
 		return nil, fmt.Errorf("file %s not stored", name)
@@ -116,9 +91,6 @@ func (ms *MemoryStore) GetFile(name string) ([]byte, error) {
 
 // SetFile sets or replaces the contents of a configuration file.
 func (ms *MemoryStore) SetFile(name string, data []byte) error {
-	ms.configLock.Lock()
-	defer ms.configLock.Unlock()
-
 	ms.files[name] = data
 
 	return nil
@@ -126,18 +98,12 @@ func (ms *MemoryStore) SetFile(name string, data []byte) error {
 
 // HasFile returns true if the given file was previously persisted.
 func (ms *MemoryStore) HasFile(name string) (bool, error) {
-	ms.configLock.RLock()
-	defer ms.configLock.RUnlock()
-
 	_, ok := ms.files[name]
 	return ok, nil
 }
 
 // RemoveFile removes a previously persisted configuration file.
 func (ms *MemoryStore) RemoveFile(name string) error {
-	ms.configLock.Lock()
-	defer ms.configLock.Unlock()
-
 	delete(ms.files, name)
 
 	return nil
@@ -152,3 +118,8 @@ func (ms *MemoryStore) String() string {
 func (ms *MemoryStore) Close() error {
 	return nil
 }
+
+// Watch nothing on memory store
+func (ms *MemoryStore) Watch(_ func()) error {
+	return nil
+}