Cleaned up some error handling/comments around config entries

agent/consul/fsm/commands_oss_test.go

@@ -1369,7 +1369,7 @@ func TestFSM_ConfigEntry(t *testing.T) {
 		Kind: structs.ProxyDefaults,
 		Name: "global",
 		Config: map[string]interface{}{
-			"DestinationServiceName": "foo",
+			"foo": "bar",
 		},
 	}
 
@@ -1399,8 +1399,8 @@ func TestFSM_ConfigEntry(t *testing.T) {
 		require.True(ok)
 
 		// Read the map[string]interface{} back out.
-		value, _ := proxyConf.Config["DestinationServiceName"].([]uint8)
-		proxyConf.Config["DestinationServiceName"] = structs.Uint8ToString(value)
+		value, _ := proxyConf.Config["foo"].([]uint8)
+		proxyConf.Config["foo"] = structs.Uint8ToString(value)
 
 		require.Equal(entry, config)
 	}

agent/consul/fsm/snapshot_oss.go

@@ -375,6 +375,9 @@ func (s *snapshot) persistConfigEntries(sink raft.SnapshotSink,
 		if _, err := sink.Write([]byte{byte(structs.ConfigEntryRequestType)}); err != nil {
 			return err
 		}
+		// Encode the entry request without an operation since we don't need it for restoring.
+		// The request is used for its custom decoding/encoding logic around the ConfigEntry
+		// interface.
 		req := &structs.ConfigEntryRequest{
 			Entry: entry,
 		}

agent/structs/config_entry.go

@@ -198,7 +198,11 @@ func (r *ConfigEntryRequest) UnmarshalBinary(data []byte) error {
 	}
 
 	// Then decode the real thing with appropriate kind of ConfigEntry
-	r.Entry = makeConfigEntry(kind)
+	entry, err := makeConfigEntry(kind)
+	if err != nil {
+		return err
+	}
+	r.Entry = entry
 
 	// Alias juggling to prevent infinite recursive calls back to this decode
 	// method.
@@ -214,13 +218,13 @@ func (r *ConfigEntryRequest) UnmarshalBinary(data []byte) error {
 	return nil
 }
 
-func makeConfigEntry(kind string) ConfigEntry {
+func makeConfigEntry(kind string) (ConfigEntry, error) {
 	switch kind {
 	case ServiceDefaults:
-		return &ServiceConfigEntry{}
+		return &ServiceConfigEntry{}, nil
 	case ProxyDefaults:
-		return &ProxyConfigEntry{}
+		return &ProxyConfigEntry{}, nil
 	default:
-		panic("invalid kind")
+		return nil, fmt.Errorf("invalid config entry kind: %s", kind)
 	}
 }

agent/structs/structs.go

@@ -55,7 +55,7 @@ const (
 	ACLPolicySetRequestType                = 19
 	ACLPolicyDeleteRequestType             = 20
 	ConnectCALeafRequestType               = 21
-	ConfigEntryRequestType                 = 22 // FSM snapshots only.
+	ConfigEntryRequestType                 = 22
 )
 
 const (