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>
2020-10-29 15:54:39 -07:00
--- a/config/store.go
+++ b/config/store.go
@@ -4,37 +4,26 @@
 package config

 import (
+	"bytes"
+	"encoding/json"
 	"strings"
+	"sync"

 	"github.com/mattermost/mattermost-server/v5/model"
+	"github.com/mattermost/mattermost-server/v5/utils/jsonutils"
+	"github.com/pkg/errors"
 )

 // Listener is a callback function invoked when the configuration changes.
 type Listener func(oldConfig *model.Config, newConfig *model.Config)

-// Store abstracts the act of getting and setting the configuration.
-type Store interface {
-	// Get fetches the current, cached configuration.
-	Get() *model.Config
-
-	// GetEnvironmentOverrides fetches the configuration fields overridden by environment variables.
-	GetEnvironmentOverrides() map[string]interface{}
-
-	// RemoveEnvironmentOverrides returns a new config without the environment
-	// overrides
-	RemoveEnvironmentOverrides(cfg *model.Config) *model.Config
-
+type BackingStore interface {
 	// Set replaces the current configuration in its entirety and updates the backing store.
-	Set(*model.Config) (*model.Config, error)
+	Set(*model.Config) error

-	// Load updates the current configuration from the backing store, possibly initializing.
-	Load() (err error)
-
-	// AddListener adds a callback function to invoke when the configuration is modified.
-	AddListener(listener Listener) string
-
-	// RemoveListener removes a callback function using an id returned from AddListener.
-	RemoveListener(id string)
+	// Load retrieves the configuration stored. If there is no configuration stored
+	// the io.ReadCloser will be nil
+	Load() ([]byte, error)

 	// GetFile fetches the contents of a previously persisted configuration file.
 	// If no such file exists, an empty byte array will be returned without error.
@@ -52,15 +41,247 @@ type Store interface {
 	// String describes the backing store for the config.
 	String() string

+	Watch(callback func()) error
+
 	// Close cleans up resources associated with the store.
 	Close() error
 }

 // NewStore creates a database or file store given a data source name by which to connect.
-func NewStore(dsn string, watch bool) (Store, error) {
+func NewStore(dsn string, watch bool) (*Store, error) {
+	backingStore, err := getBackingStore(dsn, watch)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewStoreFromBacking(backingStore)
+
+}
+
+func NewStoreFromBacking(backingStore BackingStore) (*Store, error) {
+	store := &Store{
+		backingStore: backingStore,
+	}
+
+	if err := store.Load(); err != nil {
+		return nil, errors.Wrap(err, "unable to load on store creation")
+	}
+
+	if err := backingStore.Watch(func() {
+		store.Load()
+	}); err != nil {
+		return nil, errors.Wrap(err, "failed to watch backing store")
+	}
+
+	return store, nil
+}
+
+func getBackingStore(dsn string, watch bool) (BackingStore, error) {
 	if strings.HasPrefix(dsn, "mysql://") || strings.HasPrefix(dsn, "postgres://") {
 		return NewDatabaseStore(dsn)
 	}

 	return NewFileStore(dsn, watch)
 }
+
+func NewTestMemoryStore() *Store {
+	memoryStore, err := NewMemoryStore()
+	if err != nil {
+		panic("failed to initialize memory store: " + err.Error())
+	}
+
+	configStore, err := NewStoreFromBacking(memoryStore)
+	if err != nil {
+		panic("failed to initialize config store: " + err.Error())
+	}
+
+	return configStore
+}
+
+type Store struct {
+	emitter
+	backingStore BackingStore
+
+	configLock  sync.RWMutex
+	config      *model.Config
+	configNoEnv *model.Config
+
+	persistFeatureFlags bool
+}
+
+// Get fetches the current, cached configuration.
+func (s *Store) Get() *model.Config {
+	s.configLock.RLock()
+	defer s.configLock.RUnlock()
+	return s.config
+}
+
+// Get fetches the current, cached configuration without environment variable overrides.
+func (s *Store) GetNoEnv() *model.Config {
+	s.configLock.RLock()
+	defer s.configLock.RUnlock()
+	return s.configNoEnv
+}
+
+// GetEnvironmentOverrides fetches the configuration fields overridden by environment variables.
+func (s *Store) GetEnvironmentOverrides() map[string]interface{} {
+	return generateEnvironmentMap(GetEnvironment())
+}
+
+// RemoveEnvironmentOverrides returns a new config without the environment
+// overrides
+func (s *Store) RemoveEnvironmentOverrides(cfg *model.Config) *model.Config {
+	s.configLock.RLock()
+	defer s.configLock.RUnlock()
+	return removeEnvOverrides(cfg, s.configNoEnv, s.GetEnvironmentOverrides())
+}
+
+// PersistFeatures sets if the store should persist feature flags.
+func (s *Store) PersistFeatures(persist bool) {
+	s.configLock.Lock()
+	defer s.configLock.Unlock()
+	s.persistFeatureFlags = persist
+}
+
+// Set replaces the current configuration in its entirety and updates the backing store.
+func (s *Store) Set(newCfg *model.Config) (*model.Config, error) {
+	s.configLock.Lock()
+	var unlockOnce sync.Once
+	defer unlockOnce.Do(s.configLock.Unlock)
+
+	oldCfg := s.config.Clone()
+
+	// Really just for some tests we need to set defaults here
+	newCfg.SetDefaults()
+
+	// Sometimes the config is received with "fake" data in sensitive fields. Apply the real
+	// data from the existing config as necessary.
+	desanitize(oldCfg, newCfg)
+
+	if err := newCfg.IsValid(); err != nil {
+		return nil, errors.Wrap(err, "new configuration is invalid")
+	}
+
+	newCfg = removeEnvOverrides(newCfg, s.configNoEnv, s.GetEnvironmentOverrides())
+
+	// Don't persist feature flags unless we are on MM cloud
+	// MM cloud uses config in the DB as a cache of the feature flag
+	// settings in case the managment system is down when a pod starts.
+	if !s.persistFeatureFlags {
+		newCfg.FeatureFlags = nil
+	}
+
+	if err := s.backingStore.Set(newCfg); err != nil {
+		return nil, errors.Wrap(err, "failed to persist")
+	}
+
+	if err := s.loadLockedWithOld(oldCfg, &unlockOnce); err != nil {
+		return nil, errors.Wrap(err, "failed to load on save")
+	}
+
+	return oldCfg, nil
+}
+
+func (s *Store) loadLockedWithOld(oldCfg *model.Config, unlockOnce *sync.Once) error {
+	configBytes, err := s.backingStore.Load()
+	if err != nil {
+		return err
+	}
+
+	loadedConfig := &model.Config{}
+	if len(configBytes) != 0 {
+		if err = json.Unmarshal(configBytes, &loadedConfig); err != nil {
+			return jsonutils.HumanizeJsonError(err, configBytes)
+		}
+	}
+
+	loadedConfig.SetDefaults()
+
+	s.configNoEnv = loadedConfig.Clone()
+	fixConfig(s.configNoEnv)
+
+	loadedConfig = applyEnvironmentMap(loadedConfig, GetEnvironment())
+
+	fixConfig(loadedConfig)
+
+	if err := loadedConfig.IsValid(); err != nil {
+		return errors.Wrap(err, "invalid config")
+	}
+
+	// Apply changes that may have happened on load to the backing store.
+	oldCfgBytes, err := json.Marshal(oldCfg)
+	if err != nil {
+		return errors.Wrap(err, "failed to marshal old config")
+	}
+	newCfgBytes, err := json.Marshal(loadedConfig)
+	if err != nil {
+		return errors.Wrap(err, "failed to marshal loaded config")
+	}
+	if len(configBytes) == 0 || !bytes.Equal(oldCfgBytes, newCfgBytes) {
+		if err := s.backingStore.Set(s.configNoEnv); err != nil {
+			if !errors.Is(err, ErrReadOnlyConfiguration) {
+				return errors.Wrap(err, "failed to persist")
+			}
+		}
+	}
+
+	s.config = loadedConfig
+
+	unlockOnce.Do(s.configLock.Unlock)
+
+	s.invokeConfigListeners(oldCfg, loadedConfig)
+
+	return nil
+}
+
+// Load updates the current configuration from the backing store, possibly initializing.
+func (s *Store) Load() error {
+	s.configLock.Lock()
+	var unlockOnce sync.Once
+	defer unlockOnce.Do(s.configLock.Unlock)
+
+	oldCfg := s.config.Clone()
+
+	return s.loadLockedWithOld(oldCfg, &unlockOnce)
+}
+
+// GetFile fetches the contents of a previously persisted configuration file.
+// If no such file exists, an empty byte array will be returned without error.
+func (s *Store) GetFile(name string) ([]byte, error) {
+	s.configLock.RLock()
+	defer s.configLock.RUnlock()
+	return s.backingStore.GetFile(name)
+}
+
+// SetFile sets or replaces the contents of a configuration file.
+func (s *Store) SetFile(name string, data []byte) error {
+	s.configLock.Lock()
+	defer s.configLock.Unlock()
+	return s.backingStore.SetFile(name, data)
+}
+
+// HasFile returns true if the given file was previously persisted.
+func (s *Store) HasFile(name string) (bool, error) {
+	s.configLock.RLock()
+	defer s.configLock.RUnlock()
+	return s.backingStore.HasFile(name)
+}
+
+// RemoveFile removes a previously persisted configuration file.
+func (s *Store) RemoveFile(name string) error {
+	s.configLock.Lock()
+	defer s.configLock.Unlock()
+	return s.backingStore.RemoveFile(name)
+}
+
+// String describes the backing store for the config.
+func (s *Store) String() string {
+	return s.backingStore.String()
+}
+
+// Close cleans up resources associated with the store.
+func (s *Store) Close() error {
+	s.configLock.Lock()
+	defer s.configLock.Unlock()
+	return s.backingStore.Close()
+}