Add support for process launch env. vars.

build.go

@@ -331,6 +331,14 @@ func Build(f BuildFunc, options ...Option) {
 			config.exitHandler.Error(err)
 			return
 		}
+
+		for process, processEnv := range layer.ProcessLaunchEnv {
+			err = config.envWriter.Write(filepath.Join(layer.Path, "env.launch", process), processEnv)
+			if err != nil {
+				config.exitHandler.Error(err)
+				return
+			}
+		}
 	}
 
 	if !result.Launch.isEmpty() {

build_test.go

@@ -711,6 +711,41 @@ api = "0.4"
 					Expect(string(contents)).To(Equal(fmt.Sprintf("%s-value", modifier)))
 				}
 			})
+			it("writes env vars into env.launch/<process> directory", func() {
+				packit.Build(func(ctx packit.BuildContext) (packit.BuildResult, error) {
+					return packit.BuildResult{
+						Layers: []packit.Layer{
+							{
+								Path: filepath.Join(ctx.Layers.Path, "some-layer"),
+								ProcessLaunchEnv: map[string]packit.Environment{
+									"process-name": {
+										"SOME_VAR.append":   "append-value",
+										"SOME_VAR.default":  "default-value",
+										"SOME_VAR.delim":    "delim-value",
+										"SOME_VAR.prepend":  "prepend-value",
+										"SOME_VAR.override": "override-value",
+									},
+									"another-process-name": {
+										"SOME_VAR.append":   "append-value",
+										"SOME_VAR.default":  "default-value",
+										"SOME_VAR.delim":    "delim-value",
+										"SOME_VAR.prepend":  "prepend-value",
+										"SOME_VAR.override": "override-value",
+									},
+								},
+							},
+						},
+					}, nil
+				}, packit.WithArgs([]string{binaryPath, layersDir, "", planPath}))
+
+				for _, process := range []string{"process-name", "another-process-name"} {
+					for _, modifier := range []string{"append", "default", "delim", "prepend", "override"} {
+						contents, err := ioutil.ReadFile(filepath.Join(layersDir, "some-layer", "env.launch", process, fmt.Sprintf("SOME_VAR.%s", modifier)))
+						Expect(err).NotTo(HaveOccurred())
+						Expect(string(contents)).To(Equal(fmt.Sprintf("%s-value", modifier)))
+					}
+				}
+			})
 		})
 
 		context("writes to build folder", func() {

layer.go

@@ -48,6 +48,11 @@ type Layer struct {
 	// https://github.com/buildpacks/spec/blob/main/buildpack.md#provided-by-the-buildpacks.
 	LaunchEnv Environment `toml:"-"`
 
+	// ProcessLaunchEnv is a map of environment variables attached to the layer and
+	// made available to specified proccesses in the launch phase accoring to the specification:
+	// https://github.com/buildpacks/spec/blob/main/buildpack.md#provided-by-the-buildpacks
+	ProcessLaunchEnv map[string]Environment `toml:"-"`
+
 	// Metadata is an unspecified field allowing buildpacks to communicate extra
 	// details about the layer. Examples of this type of metadata might include
 	// details about what versions of software are included in the layer such
@@ -69,7 +74,7 @@ func (l Layer) Reset() (Layer, error) {
 	l.SharedEnv = Environment{}
 	l.BuildEnv = Environment{}
 	l.LaunchEnv = Environment{}
-
+	l.ProcessLaunchEnv = make(map[string]Environment)
 	l.Metadata = nil
 
 	err := os.RemoveAll(l.Path)

layer_test.go

@@ -49,14 +49,15 @@ func testLayer(t *testing.T, context spec.G, it spec.S) {
 				Expect(err).NotTo(HaveOccurred())
 
 				Expect(layer).To(Equal(packit.Layer{
-					Name:      "some-layer",
-					Path:      filepath.Join(layersDir, "some-layer"),
-					Launch:    false,
-					Build:     false,
-					Cache:     false,
-					SharedEnv: packit.Environment{},
-					BuildEnv:  packit.Environment{},
-					LaunchEnv: packit.Environment{},
+					Name:             "some-layer",
+					Path:             filepath.Join(layersDir, "some-layer"),
+					Launch:           false,
+					Build:            false,
+					Cache:            false,
+					SharedEnv:        packit.Environment{},
+					BuildEnv:         packit.Environment{},
+					LaunchEnv:        packit.Environment{},
+					ProcessLaunchEnv: map[string]packit.Environment{},
 				}))
 
 				Expect(filepath.Join(layersDir, "some-layer")).To(BeADirectory())
@@ -118,14 +119,15 @@ func testLayer(t *testing.T, context spec.G, it spec.S) {
 					Expect(err).NotTo(HaveOccurred())
 
 					Expect(layer).To(Equal(packit.Layer{
-						Name:      "some-layer",
-						Path:      filepath.Join(layersDir, "some-layer"),
-						Launch:    false,
-						Build:     false,
-						Cache:     false,
-						SharedEnv: packit.Environment{},
-						BuildEnv:  packit.Environment{},
-						LaunchEnv: packit.Environment{},
+						Name:             "some-layer",
+						Path:             filepath.Join(layersDir, "some-layer"),
+						Launch:           false,
+						Build:            false,
+						Cache:            false,
+						SharedEnv:        packit.Environment{},
+						BuildEnv:         packit.Environment{},
+						LaunchEnv:        packit.Environment{},
+						ProcessLaunchEnv: map[string]packit.Environment{},
 					}))
 
 					Expect(filepath.Join(layersDir, "some-layer")).To(BeADirectory())

layers.go

@@ -2,6 +2,7 @@ package packit
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
 	"path/filepath"
 
@@ -20,11 +21,12 @@ type Layers struct {
 // disk and returned instead.
 func (l Layers) Get(name string) (Layer, error) {
 	layer := Layer{
-		Path:      filepath.Join(l.Path, name),
-		Name:      name,
-		SharedEnv: Environment{},
-		BuildEnv:  Environment{},
-		LaunchEnv: Environment{},
+		Path:             filepath.Join(l.Path, name),
+		Name:             name,
+		SharedEnv:        Environment{},
+		BuildEnv:         Environment{},
+		LaunchEnv:        Environment{},
+		ProcessLaunchEnv: make(map[string]Environment),
 	}
 
 	_, err := toml.DecodeFile(filepath.Join(l.Path, fmt.Sprintf("%s.toml", name)), &layer)
@@ -49,5 +51,21 @@ func (l Layers) Get(name string) (Layer, error) {
 		return Layer{}, err
 	}
 
+	if _, err := os.Stat(filepath.Join(l.Path, name, "env.launch")); !os.IsNotExist(err) {
+		paths, err := ioutil.ReadDir(filepath.Join(l.Path, name, "env.launch"))
+		if err != nil {
+			return Layer{}, err
+		}
+
+		for _, path := range paths {
+			if path.IsDir() {
+				layer.ProcessLaunchEnv[path.Name()], err = newEnvironmentFromPath(filepath.Join(l.Path, name, "env.launch", path.Name()))
+				if err != nil {
+					return Layer{}, err
+				}
+			}
+		}
+	}
+
 	return layer, nil
 }

layers_test.go

@@ -39,11 +39,12 @@ func testLayers(t *testing.T, context spec.G, it spec.S) {
 			layer, err := layers.Get("some-layer")
 			Expect(err).NotTo(HaveOccurred())
 			Expect(layer).To(Equal(packit.Layer{
-				Name:      "some-layer",
-				Path:      filepath.Join(layersDir, "some-layer"),
-				SharedEnv: packit.Environment{},
-				BuildEnv:  packit.Environment{},
-				LaunchEnv: packit.Environment{},
+				Name:             "some-layer",
+				Path:             filepath.Join(layersDir, "some-layer"),
+				SharedEnv:        packit.Environment{},
+				BuildEnv:         packit.Environment{},
+				LaunchEnv:        packit.Environment{},
+				ProcessLaunchEnv: map[string]packit.Environment{},
 			}))
 		})
 
@@ -63,14 +64,15 @@ some-key = "some-value"`), 0644)
 				layer, err := layers.Get("some-layer")
 				Expect(err).NotTo(HaveOccurred())
 				Expect(layer).To(Equal(packit.Layer{
-					Name:      "some-layer",
-					Path:      filepath.Join(layersDir, "some-layer"),
-					Launch:    true,
-					Build:     true,
-					Cache:     true,
-					SharedEnv: packit.Environment{},
-					BuildEnv:  packit.Environment{},
-					LaunchEnv: packit.Environment{},
+					Name:             "some-layer",
+					Path:             filepath.Join(layersDir, "some-layer"),
+					Launch:           true,
+					Build:            true,
+					Cache:            true,
+					SharedEnv:        packit.Environment{},
+					BuildEnv:         packit.Environment{},
+					LaunchEnv:        packit.Environment{},
+					ProcessLaunchEnv: map[string]packit.Environment{},
 					Metadata: map[string]interface{}{
 						"some-key": "some-value",
 					},
@@ -108,6 +110,35 @@ some-key = "some-value"`), 0644)
 
 					err = ioutil.WriteFile(filepath.Join(launchEnvDir, "PREPEND_VAR.delim"), []byte("#"), 0644)
 					Expect(err).NotTo(HaveOccurred())
+
+					processLaunchEnvDir := filepath.Join(layersDir, "some-layer", "env.launch", "process")
+					Expect(os.MkdirAll(processLaunchEnvDir, os.ModePerm)).To(Succeed())
+
+					err = ioutil.WriteFile(filepath.Join(processLaunchEnvDir, "APPEND_VAR.append"), []byte("append-value"), 0644)
+					Expect(err).NotTo(HaveOccurred())
+
+					err = ioutil.WriteFile(filepath.Join(processLaunchEnvDir, "APPEND_VAR.delim"), []byte("!"), 0644)
+					Expect(err).NotTo(HaveOccurred())
+
+					err = ioutil.WriteFile(filepath.Join(processLaunchEnvDir, "PREPEND_VAR.prepend"), []byte("prepend-value"), 0644)
+					Expect(err).NotTo(HaveOccurred())
+
+					err = ioutil.WriteFile(filepath.Join(processLaunchEnvDir, "PREPEND_VAR.delim"), []byte("#"), 0644)
+					Expect(err).NotTo(HaveOccurred())
+					anotherProcessLaunchEnvDir := filepath.Join(layersDir, "some-layer", "env.launch", "another-process")
+					Expect(os.MkdirAll(anotherProcessLaunchEnvDir, os.ModePerm)).To(Succeed())
+
+					err = ioutil.WriteFile(filepath.Join(anotherProcessLaunchEnvDir, "APPEND_VAR.append"), []byte("append-value"), 0644)
+					Expect(err).NotTo(HaveOccurred())
+
+					err = ioutil.WriteFile(filepath.Join(anotherProcessLaunchEnvDir, "APPEND_VAR.delim"), []byte("!"), 0644)
+					Expect(err).NotTo(HaveOccurred())
+
+					err = ioutil.WriteFile(filepath.Join(anotherProcessLaunchEnvDir, "PREPEND_VAR.prepend"), []byte("prepend-value"), 0644)
+					Expect(err).NotTo(HaveOccurred())
+
+					err = ioutil.WriteFile(filepath.Join(anotherProcessLaunchEnvDir, "PREPEND_VAR.delim"), []byte("#"), 0644)
+					Expect(err).NotTo(HaveOccurred())
 				})
 
 				it("returns a layer with the existing metadata", func() {
@@ -119,6 +150,20 @@ some-key = "some-value"`), 0644)
 						Launch: true,
 						Build:  true,
 						Cache:  true,
+						ProcessLaunchEnv: map[string]packit.Environment{
+							"process": {
+								"APPEND_VAR.append":   "append-value",
+								"APPEND_VAR.delim":    "!",
+								"PREPEND_VAR.prepend": "prepend-value",
+								"PREPEND_VAR.delim":   "#",
+							},
+							"another-process": {
+								"APPEND_VAR.append":   "append-value",
+								"APPEND_VAR.delim":    "!",
+								"PREPEND_VAR.prepend": "prepend-value",
+								"PREPEND_VAR.delim":   "#",
+							},
+						},
 						SharedEnv: packit.Environment{
 							"OVERRIDE_VAR.override": "override-value",
 						},