1// Copyright 2017 Google LLC. All Rights Reserved. 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14 15package gnostic_extension_v1 16 17import ( 18 "io/ioutil" 19 "log" 20 "os" 21 22 "github.com/golang/protobuf/proto" 23 "github.com/golang/protobuf/ptypes" 24) 25 26type extensionHandler func(name string, yamlInput string) (bool, proto.Message, error) 27 28// Main implements the main program of an extension handler. 29func Main(handler extensionHandler) { 30 // unpack the request 31 data, err := ioutil.ReadAll(os.Stdin) 32 if err != nil { 33 log.Println("File error:", err.Error()) 34 os.Exit(1) 35 } 36 if len(data) == 0 { 37 log.Println("No input data.") 38 os.Exit(1) 39 } 40 request := &ExtensionHandlerRequest{} 41 err = proto.Unmarshal(data, request) 42 if err != nil { 43 log.Println("Input error:", err.Error()) 44 os.Exit(1) 45 } 46 // call the handler 47 handled, output, err := handler(request.Wrapper.ExtensionName, request.Wrapper.Yaml) 48 // respond with the output of the handler 49 response := &ExtensionHandlerResponse{ 50 Handled: false, // default assumption 51 Errors: make([]string, 0), 52 } 53 if err != nil { 54 response.Errors = append(response.Errors, err.Error()) 55 } else if handled { 56 response.Handled = true 57 response.Value, err = ptypes.MarshalAny(output) 58 if err != nil { 59 response.Errors = append(response.Errors, err.Error()) 60 } 61 } 62 responseBytes, _ := proto.Marshal(response) 63 os.Stdout.Write(responseBytes) 64} 65