Add support for working-directory in launch.toml (API>=0.8)

application.go

@@ -48,6 +48,9 @@ type Process struct {
 	// Command is exec'd directly by the os (no profile.d scripts run)
 	Direct bool `toml:"direct,omitempty"`
 
+	// WorkingDirectory is a directory to execute the command in, removes the need to use a shell environment to CD into working directory
+	WorkingDirectory string `toml:"working-directory,omitempty"`
+
 	// Default can be set to true to indicate that the process
 	// type being defined should be the default process type for the app image.
 	Default bool `toml:"default,omitempty"`

build.go

@@ -171,8 +171,8 @@ func Build(builder Builder, options ...Option) {
 	logger.Debugf("Buildpack: %+v", ctx.Buildpack)
 
 	API := strings.TrimSpace(ctx.Buildpack.API)
-	if API != "0.5" && API != "0.6" && API != "0.7" {
-		config.exitHandler.Error(errors.New("this version of libcnb is only compatible with buildpack APIs 0.5, 0.6, and 0.7"))
+	if API != "0.5" && API != "0.6" && API != "0.7" && API != "0.8" {
+		config.exitHandler.Error(errors.New("this version of libcnb is only compatible with buildpack APIs 0.5, 0.6, 0.7 and 0.8"))
 		return
 	}
 
@@ -346,6 +346,15 @@ func Build(builder Builder, options ...Option) {
 			}
 		}
 
+		if API != "0.8" {
+			for i, process := range launch.Processes {
+				if process.WorkingDirectory != "" {
+					logger.Infof("WARNING: Launch layer is setting working-directory=%s, but that is not supported until API version 0.8. This setting will be ignored.", process.WorkingDirectory)
+					launch.Processes[i].WorkingDirectory = ""
+				}
+			}
+		}
+
 		if err = config.tomlWriter.Write(file, launch); err != nil {
 			config.exitHandler.Error(fmt.Errorf("unable to write application metadata %s\n%w", file, err))
 			return

build_test.go

@@ -204,7 +204,7 @@ version = "1.1.1"
 			)
 
 			Expect(exitHandler.Calls[0].Arguments.Get(0)).To(MatchError(
-				"this version of libcnb is only compatible with buildpack APIs 0.5, 0.6, and 0.7",
+				"this version of libcnb is only compatible with buildpack APIs 0.5, 0.6, 0.7 and 0.8",
 			))
 		})
 	})
@@ -549,6 +549,72 @@ version = "1.1.1"
 		}))
 	})
 
+	it("ignore working-directory setting and writes launch.toml (API<0.8)", func() {
+		builder.On("Build", mock.Anything).Return(libcnb.BuildResult{
+			Processes: []libcnb.Process{
+				{
+					Type:             "test-type",
+					Command:          "test-command-in-dir",
+					Default:          true,
+					WorkingDirectory: "/my/directory/",
+				},
+			},
+		}, nil)
+
+		libcnb.Build(builder,
+			libcnb.WithBOMLabel(true),
+			libcnb.WithArguments([]string{commandPath, layersPath, platformPath, buildpackPlanPath}),
+			libcnb.WithTOMLWriter(tomlWriter),
+		)
+
+		Expect(tomlWriter.Calls[0].Arguments[0]).To(Equal(filepath.Join(layersPath, "launch.toml")))
+		Expect(tomlWriter.Calls[0].Arguments[1]).To(Equal(libcnb.LaunchTOML{
+			Processes: []libcnb.Process{
+				{
+					Type:    "test-type",
+					Command: "test-command-in-dir",
+					Default: true,
+				},
+			},
+		}))
+	})
+
+	it("writes launch.toml with working-directory setting(API>=0.8)", func() {
+		var b bytes.Buffer
+		err := buildpackTOML.Execute(&b, map[string]string{"APIVersion": "0.8"})
+		Expect(err).ToNot(HaveOccurred())
+
+		Expect(ioutil.WriteFile(filepath.Join(buildpackPath, "buildpack.toml"), b.Bytes(), 0600)).To(Succeed())
+		builder.On("Build", mock.Anything).Return(libcnb.BuildResult{
+			Processes: []libcnb.Process{
+				{
+					Type:             "test-type",
+					Command:          "test-command-in-dir",
+					Default:          true,
+					WorkingDirectory: "/my/directory/",
+				},
+			},
+		}, nil)
+
+		libcnb.Build(builder,
+			libcnb.WithBOMLabel(true),
+			libcnb.WithArguments([]string{commandPath, layersPath, platformPath, buildpackPlanPath}),
+			libcnb.WithTOMLWriter(tomlWriter),
+		)
+
+		Expect(tomlWriter.Calls[0].Arguments[0]).To(Equal(filepath.Join(layersPath, "launch.toml")))
+		Expect(tomlWriter.Calls[0].Arguments[1]).To(Equal(libcnb.LaunchTOML{
+			Processes: []libcnb.Process{
+				{
+					Type:             "test-type",
+					Command:          "test-command-in-dir",
+					Default:          true,
+					WorkingDirectory: "/my/directory/",
+				},
+			},
+		}))
+	})
+
 	it("writes persistent metadata", func() {
 		m := map[string]interface{}{"test-key": "test-value"}