Add Truncate and ReadOnly options to Badger storage backend, closes #…

…1832

plugin/storage/badger/factory.go

@@ -110,6 +110,10 @@ func (f *Factory) Initialize(metricsFactory metrics.Factory, logger *zap.Logger)
 		opts.SyncWrites = f.Options.primary.SyncWrites
 		opts.Dir = f.Options.primary.KeyDirectory
 		opts.ValueDir = f.Options.primary.ValueDirectory
+
+		// These options make no sense with ephemeral data
+		opts.Truncate = f.Options.primary.Truncate
+		opts.ReadOnly = f.Options.primary.ReadOnly
 	}
 
 	store, err := badger.Open(opts)

plugin/storage/badger/options.go

@@ -31,14 +31,18 @@ type Options struct {
 
 // NamespaceConfig is badger's internal configuration data
 type NamespaceConfig struct {
-	namespace             string
-	SpanStoreTTL          time.Duration
+	namespace    string
+	SpanStoreTTL time.Duration
+
+	// Defining ValueDirectory and KeyDirectory will make Ephemeral false
 	ValueDirectory        string
 	KeyDirectory          string
 	Ephemeral             bool // Setting this to true will ignore ValueDirectory and KeyDirectory
 	SyncWrites            bool
 	MaintenanceInterval   time.Duration
 	MetricsUpdateInterval time.Duration
+	Truncate              bool
+	ReadOnly              bool
 }
 
 const (
@@ -55,6 +59,8 @@ const (
 	suffixSyncWrite           = ".consistency"
 	suffixMaintenanceInterval = ".maintenance-interval"
 	suffixMetricsInterval     = ".metrics-update-interval" // Intended only for testing purposes
+	suffixTruncate            = ".truncate"
+	suffixReadOnly            = ".read-only"
 	defaultDataDir            = string(os.PathSeparator) + "data"
 	defaultValueDir           = defaultDataDir + string(os.PathSeparator) + "values"
 	defaultKeysDir            = defaultDataDir + string(os.PathSeparator) + "keys"
@@ -116,7 +122,7 @@ func addFlags(flagSet *flag.FlagSet, nsConfig *NamespaceConfig) {
 	flagSet.Bool(
 		nsConfig.namespace+suffixSyncWrite,
 		nsConfig.SyncWrites,
-		"If all writes should be synced immediately. This can impact write performance.",
+		"If all writes should be synced immediately to physical disk. This will impact write performance.",
 	)
 	flagSet.Duration(
 		nsConfig.namespace+suffixMaintenanceInterval,
@@ -128,6 +134,16 @@ func addFlags(flagSet *flag.FlagSet, nsConfig *NamespaceConfig) {
 		nsConfig.MetricsUpdateInterval,
 		"How often the badger metrics are collected by Jaeger. Format is time.Duration (https://golang.org/pkg/time/#Duration)",
 	)
+	flagSet.Bool(
+		nsConfig.namespace+suffixTruncate,
+		nsConfig.Truncate,
+		"If write-ahead-log should be truncated on restart. this will cause data loss.",
+	)
+	flagSet.Bool(
+		nsConfig.namespace+suffixReadOnly,
+		nsConfig.ReadOnly,
+		"Allows to open badger database in read only mode. Multiple instances can open same database in read-only mode. Values still in the write-ahead-log must be replayed before opening.",
+	)
 }
 
 // InitFromViper initializes Options with properties from viper
@@ -143,6 +159,8 @@ func initFromViper(cfg *NamespaceConfig, v *viper.Viper) {
 	cfg.SpanStoreTTL = v.GetDuration(cfg.namespace + suffixSpanstoreTTL)
 	cfg.MaintenanceInterval = v.GetDuration(cfg.namespace + suffixMaintenanceInterval)
 	cfg.MetricsUpdateInterval = v.GetDuration(cfg.namespace + suffixMetricsInterval)
+	cfg.Truncate = v.GetBool(cfg.namespace + suffixTruncate)
+	cfg.ReadOnly = v.GetBool(cfg.namespace + suffixReadOnly)
 }
 
 // GetPrimary returns the primary namespace configuration

plugin/storage/badger/options_test.go

@@ -51,4 +51,19 @@ func TestParseOptions(t *testing.T) {
 	assert.Equal(t, time.Duration(168*time.Hour), opts.GetPrimary().SpanStoreTTL)
 	assert.Equal(t, "/var/lib/badger", opts.GetPrimary().KeyDirectory)
 	assert.Equal(t, "/mnt/slow/badger", opts.GetPrimary().ValueDirectory)
+	assert.False(t, opts.GetPrimary().ReadOnly)
+	assert.False(t, opts.GetPrimary().Truncate)
+}
+
+func TestTruncateAndReadOnlyOptions(t *testing.T) {
+	opts := NewOptions("badger")
+	v, command := config.Viperize(opts.AddFlags)
+	command.ParseFlags([]string{
+		"--badger.truncate=true",
+		"--badger.read-only=true",
+	})
+	opts.InitFromViper(v)
+
+	assert.True(t, opts.GetPrimary().ReadOnly)
+	assert.True(t, opts.GetPrimary().Truncate)
 }