Exit if invalid engine is selected

Fix #4584, related to #4583

CHANGELOG.md

@@ -34,6 +34,7 @@
 - [#4124](https://github.com/influxdb/influxdb/issues/4124): Missing defer/recover/panic idiom in HTTPD service
 - [#4238](https://github.com/influxdb/influxdb/pull/4238): Fully disable hinted-handoff service if so requested.
 - [#4165](https://github.com/influxdb/influxdb/pull/4165): Tag all Go runtime stats when writing to internal database.
+- [#4586](https://github.com/influxdb/influxdb/pull/4586): Exit when invalid engine is selected
 - [#4118](https://github.com/influxdb/influxdb/issues/4118): Return consistent, correct result for SHOW MEASUREMENTS with multiple AND conditions
 - [#4191](https://github.com/influxdb/influxdb/pull/4191): Correctly marshal remote mapper responses. Fixes [#4170](https://github.com/influxdb/influxdb/issues/4170)
 - [#4222](https://github.com/influxdb/influxdb/pull/4222): Graphite TCP connections should not block shutdown

cmd/influxd/run/config.go

@@ -108,12 +108,12 @@ func NewDemoConfig() (*Config, error) {
 func (c *Config) Validate() error {
 	if c.Meta.Dir == "" {
 		return errors.New("Meta.Dir must be specified")
-	} else if c.Data.Dir == "" {
-		return errors.New("Data.Dir must be specified")
 	} else if c.HintedHandoff.Dir == "" {
 		return errors.New("HintedHandoff.Dir must be specified")
-	} else if c.Data.WALDir == "" {
-		return errors.New("Data.WALDir must be specified")
+	}
+
+	if err := c.Data.Validate(); err != nil {
+		return err
 	}
 
 	for _, g := range c.Graphites {

tsdb/config.go

@@ -1,6 +1,8 @@
 package tsdb
 
 import (
+	"errors"
+	"fmt"
 	"log"
 	"os"
 	"time"
@@ -128,3 +130,24 @@ func NewConfig() Config {
 		QueryLogEnabled: true,
 	}
 }
+
+func (c *Config) Validate() error {
+	if c.Dir == "" {
+		return errors.New("Data.Dir must be specified")
+	} else if c.WALDir == "" {
+		return errors.New("Data.WALDir must be specified")
+	}
+
+	valid := false
+	for _, e := range RegisteredEngines() {
+		if e == c.Engine {
+			valid = true
+			break
+		}
+	}
+	if !valid {
+		return fmt.Errorf("unrecognized engine %s", c.Engine)
+	}
+
+	return nil
+}

tsdb/engine.go

@@ -63,6 +63,16 @@ func RegisterEngine(name string, fn NewEngineFunc) {
 	newEngineFuncs[name] = fn
 }
 
+// RegisteredEngines returns the slice of currently registered engines.
+func RegisteredEngines() []string {
+	a := make([]string, 0, len(newEngineFuncs))
+	for k, _ := range newEngineFuncs {
+		a = append(a, k)
+	}
+	sort.Strings(a)
+	return a
+}
+
 // NewEngine returns an instance of an engine based on its format.
 // If the path does not exist then the DefaultFormat is used.
 func NewEngine(path string, walPath string, options EngineOptions) (Engine, error) {