Fix errors/panics associated with empty config sections; add warnings…

… when empty sections are found/skipped

control/config.go

@@ -465,6 +465,10 @@ func unmarshalPluginConfig(typ string, p *pluginConfig, t map[string]interface{}
				switch col := c.(type) {
				case map[string]interface{}:
					if v, ok := col["all"]; ok {
						if v == nil { // handle empty config section by converting nil value to empty map
							log.WithFields(log.Fields{"name": name, "type": typ}).Warning("Ignoring empty plugin configuration all: section")
							v = map[string]interface{}{}
						}
						jv, err := json.Marshal(v)
						if err != nil {
							return err
@@ -489,7 +493,11 @@ func unmarshalPluginConfig(typ string, p *pluginConfig, t map[string]interface{}
						case map[string]interface{}:
							for ver, version := range versions {
								switch v := version.(type) {
								case map[string]interface{}:
								case map[string]interface{}, nil:
									if v == nil { // handle empty config section by converting nil value to empty map
										log.WithFields(log.Fields{"name": name, "type": typ, "version": ver}).Warning("Ignoring empty plugin configuration version section")
										v = map[string]interface{}{}
									}
									jv, err := json.Marshal(v)
									if err != nil {
										return err
@@ -521,6 +529,9 @@ func unmarshalPluginConfig(typ string, p *pluginConfig, t map[string]interface{}
							return fmt.Errorf("Error unmarshalling %v '%v' expected '%v' got '%v'", typ, name, map[string]interface{}{}, reflect.TypeOf(versions))
						}
					}
				case nil: // ignore empty config section
					log.WithFields(log.Fields{"name": name, "type": typ}).Warning("Ignoring empty plugin configuration section")
					continue
				default:
					return fmt.Errorf("Error unmarshalling %v '%v' expected '%v' got '%v'", typ, name, map[string]interface{}{}, reflect.TypeOf(col))
				}

examples/configs/snap-config-empty.yaml

@@ -10,3 +10,8 @@ control:
      psutil:
        all:
          path: /usr/local/bin/psutil
        # this should not cause a fatal error
        versions:
          1:
      # this should also not cause a fatal error
      myplugin:

snapteld_test.go

@@ -133,7 +133,7 @@ func TestSnapConfig(t *testing.T) {

func TestSnapConfigEmpty(t *testing.T) {
	Convey("Test Config", t, func() {
		Convey("with empty all: plugin config section", func() {
		Convey("with empty plugin config sections", func() {
			cfg := getDefaultConfig()
			readConfig(cfg, "./examples/configs/snap-config-empty.yaml")
			jb, _ := json.Marshal(cfg)