github.com/paketo-buildpacks/libpak@v1.70.0/sherpa/sherpa.go (about) 1 /* 2 * Copyright 2018-2020 the original author or authors. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * https://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package sherpa 18 19 import ( 20 "fmt" 21 "os" 22 "path/filepath" 23 "strconv" 24 25 "github.com/paketo-buildpacks/libpak/internal" 26 ) 27 28 // ExecuteFunc is the callback function for buildpack helper application implementations. 29 type ExecuteFunc func() error 30 31 // Execute is called by the main function of a buildpack helper application, for execution. 32 func Execute(f ExecuteFunc, options ...Option) { 33 config := Config{ 34 exitHandler: internal.NewExitHandler(), 35 } 36 37 for _, option := range options { 38 config = option(config) 39 } 40 41 if err := f(); err != nil { 42 config.exitHandler.Error(err) 43 return 44 } 45 } 46 47 //go:generate mockery -name ExecD -case=underscore 48 49 // ExecD describes an interface for types that Exec.d specification. 50 type ExecD interface { 51 Execute() (map[string]string, error) 52 } 53 54 // Helpers is called by the main function of a buildpack's helper application, for execution. 55 func Helpers(helpers map[string]ExecD, options ...Option) error { 56 config := Config{ 57 arguments: os.Args, 58 execdWriter: os.NewFile(3, "/dev/fd/3"), 59 } 60 61 for _, option := range options { 62 config = option(config) 63 } 64 65 if len(config.arguments) == 0 { 66 return fmt.Errorf("expected command name") 67 } 68 69 c := filepath.Base(config.arguments[0]) 70 e, ok := helpers[c] 71 if !ok { 72 return fmt.Errorf("unsupported command %s", c) 73 } 74 75 r, err := e.Execute() 76 if err != nil { 77 return err 78 } 79 80 // TODO: Enable once exec.d is implemented 81 // if err := toml.NewEncoder(config.execdWriter).Encode(r); err != nil { 82 // return fmt.Errorf("unable to write environment\n%w", err) 83 // } 84 85 // TODO: Remove once exec.d is implemented 86 for k, v := range r { 87 if _, err := fmt.Fprintf(config.execdWriter, "%s=%s\n", k, strconv.Quote(v)); err != nil { 88 return fmt.Errorf("unable to write environment\n%w", err) 89 } 90 } 91 92 return nil 93 }