Ensure config contains valid index

tsdb/config.go

@@ -119,5 +119,16 @@ func (c *Config) Validate() error {
 		return fmt.Errorf("unrecognized engine %s", c.Engine)
 	}
 
+	valid = false
+	for _, e := range RegisteredIndexes() {
+		if e == c.Index {
+			valid = true
+			break
+		}
+	}
+	if !valid {
+		return fmt.Errorf("unrecognized index %s", c.Index)
+	}
+
 	return nil
 }

tsdb/config_test.go

@@ -45,4 +45,20 @@ func TestConfig_Validate_Error(t *testing.T) {
 	if err := c.Validate(); err == nil || err.Error() != "unrecognized engine fake1" {
 		t.Errorf("unexpected error: %s", err)
 	}
+
+	c.Engine = "tsm1"
+	c.Index = "foo"
+	if err := c.Validate(); err == nil || err.Error() != "unrecognized index foo" {
+		t.Errorf("unexpected error: %s", err)
+	}
+
+	c.Index = "inmem"
+	if err := c.Validate(); err != nil {
+		t.Error(err)
+	}
+
+	c.Index = "tsi1"
+	if err := c.Validate(); err != nil {
+		t.Error(err)
+	}
 }