Assign PYTHONPATH instead of PYTHONUSERBASE (#105)

- Doing this will allow other buildpacks to use PYTHONUSERBASE without
  breaking the environment setup by this buildpack, as assigning
  PYTHONUSERBASE in this buildpack prevents subsequent buildpacks from
  adding modules to the application.

Author: robdimsdale

README.md

@@ -11,7 +11,7 @@ This buildpack participates if `Pipfile` exists at the root the app.
 The buildpack will do the following:
 * At build time:
   - Installs the application packages to a layer made available to the app.
-  - Sets the `PYTHONUSERBASE` to this layer.
+  - Prepends the layer site-packages onto `PYTHONPATH`.
   - Prepends the layer's `bin` directory to the `PATH`.
 * At run time:
   - Does nothing
@@ -43,14 +43,14 @@ file that looks like the following:
   [requires.metadata]
 
     # Setting the build flag to true will ensure that the site-packages
-    # dependency is available on the $PYTHONUSERBASE/$PATH for subsequent
+    # dependency is available on the $PYTHONPATH/$PATH for subsequent
     # buildpacks during their build phase. If you are writing a buildpack that
     # needs site-packages during its build process, this flag should be
     # set to true.
     build = true
 
     # Setting the launch flag to true will ensure that the site-packages
-    # dependency is available on the $PYTHONUSERBASE/$PATH for the running
+    # dependency is available on the $PYTHONPATH/$PATH for the running
     # application. If you are writing an application that needs site-packages
     # at runtime, this flag should be set to true.
     launch = true

build.go

@@ -2,6 +2,7 @@ package pipenvinstall
 
 import (
 	"os"
+	"path/filepath"
 	"time"
 
 	"github.com/paketo-buildpacks/packit"
@@ -12,25 +13,45 @@ import (
 
 //go:generate faux --interface EntryResolver --output fakes/entry_resolver.go
 //go:generate faux --interface InstallProcess --output fakes/install_process.go
+//go:generate faux --interface SitePackagesProcess --output fakes/site_packages_process.go
+//go:generate faux --interface VenvDirLocator --output fakes/venv_dir_locator.go
 
 // EntryResolver defines the interface for picking the most relevant entry from
 // the Buildpack Plan entries.
 type EntryResolver interface {
 	MergeLayerTypes(name string, entries []packit.BuildpackPlanEntry) (launch, build bool)
 }
 
+// SitePackagesProcess defines the interface for determining the site-packages path.
+type SitePackagesProcess interface {
+	Execute(layerPath string) (sitePackagesPath string, err error)
+}
+
 // InstallProcess defines the interface for installing the pipenv dependencies.
 type InstallProcess interface {
 	Execute(workingDir string, targetLayer, cacheLayer packit.Layer) error
 }
 
+// VenvDirLocator defines the interface for locating the virtual environment
+// directory under a given path
+type VenvDirLocator interface {
+	LocateVenvDir(path string) (venvDir string, err error)
+}
+
 // Build will return a packit.BuildFunc that will be invoked during the build
 // phase of the buildpack lifecycle.
 //
 // Build will install the pipenv dependencies by using the Pipfile to a
 // packages layer. It also makes use of a cache layer to reuse the pipenv
 // cache.
-func Build(entryResolver EntryResolver, installProcess InstallProcess, clock chronos.Clock, logger scribe.Emitter) packit.BuildFunc {
+func Build(
+	entryResolver EntryResolver,
+	installProcess InstallProcess,
+	siteProcess SitePackagesProcess,
+	venvDirLocator VenvDirLocator,
+	clock chronos.Clock,
+	logger scribe.Emitter,
+) packit.BuildFunc {
 	return func(context packit.BuildContext) (packit.BuildResult, error) {
 		logger.Title("%s %s", context.BuildpackInfo.Name, context.BuildpackInfo.Version)
 
@@ -59,6 +80,22 @@ func Build(entryResolver EntryResolver, installProcess InstallProcess, clock chr
 		logger.Action("Completed in %s", duration.Round(time.Millisecond))
 		logger.Break()
 
+		venvDir, err := venvDirLocator.LocateVenvDir(packagesLayer.Path)
+		if err != nil {
+			return packit.BuildResult{}, err
+		}
+
+		sitePackagesPath, err := siteProcess.Execute(packagesLayer.Path)
+		if err != nil {
+			return packit.BuildResult{}, err
+		}
+
+		logger.Process("Configuring environment")
+		packagesLayer.SharedEnv.Prepend("PATH", filepath.Join(venvDir, "bin"), ":")
+		packagesLayer.SharedEnv.Prepend("PYTHONPATH", sitePackagesPath, string(os.PathListSeparator))
+		logger.Subprocess("%s", scribe.NewFormattedMapFromEnvironment(packagesLayer.SharedEnv))
+		logger.Break()
+
 		packagesLayer.Metadata = map[string]interface{}{
 			"built_at": clock.Now().Format(time.RFC3339Nano),
 		}

build_test.go

@@ -28,12 +28,15 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 		workingDir string
 		cnbDir     string
 
-		clock          chronos.Clock
-		timeStamp      time.Time
-		installProcess *fakes.InstallProcess
-		buffer         *bytes.Buffer
-		logEmitter     scribe.Emitter
-		entryResolver  *fakes.EntryResolver
+		clock      chronos.Clock
+		timeStamp  time.Time
+		buffer     *bytes.Buffer
+		logEmitter scribe.Emitter
+
+		entryResolver       *fakes.EntryResolver
+		installProcess      *fakes.InstallProcess
+		sitePackagesProcess *fakes.SitePackagesProcess
+		venvDirLocator      *fakes.VenvDirLocator
 
 		build packit.BuildFunc
 	)
@@ -49,8 +52,13 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 		cnbDir, err = ioutil.TempDir("", "cnb")
 		Expect(err).NotTo(HaveOccurred())
 
-		installProcess = &fakes.InstallProcess{}
 		entryResolver = &fakes.EntryResolver{}
+		installProcess = &fakes.InstallProcess{}
+		sitePackagesProcess = &fakes.SitePackagesProcess{}
+		venvDirLocator = &fakes.VenvDirLocator{}
+
+		sitePackagesProcess.ExecuteCall.Returns.SitePackagesPath = "some-site-packages-path"
+		venvDirLocator.LocateVenvDirCall.Returns.VenvDir = "some-venv-dir"
 
 		buffer = bytes.NewBuffer(nil)
 		logEmitter = scribe.NewEmitter(buffer)
@@ -60,7 +68,7 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 			return timeStamp
 		})
 
-		build = pipenvinstall.Build(entryResolver, installProcess, clock, logEmitter)
+		build = pipenvinstall.Build(entryResolver, installProcess, sitePackagesProcess, venvDirLocator, clock, logEmitter)
 	})
 
 	it.After(func() {
@@ -79,7 +87,7 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 			Plan: packit.BuildpackPlan{
 				Entries: []packit.BuildpackPlanEntry{
 					{
-						Name: pipenvinstall.SitePackages,
+						Name: "site-packages",
 					},
 				},
 			},
@@ -92,9 +100,14 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 		Expect(result).To(Equal(packit.BuildResult{
 			Layers: []packit.Layer{
 				{
-					Name:             pipenvinstall.PackagesLayerName,
-					Path:             filepath.Join(layersDir, pipenvinstall.PackagesLayerName),
-					SharedEnv:        packit.Environment{},
+					Name: "packages",
+					Path: filepath.Join(layersDir, "packages"),
+					SharedEnv: packit.Environment{
+						"PATH.delim":         ":",
+						"PATH.prepend":       filepath.Join("some-venv-dir", "bin"),
+						"PYTHONPATH.delim":   ":",
+						"PYTHONPATH.prepend": "some-site-packages-path",
+					},
 					BuildEnv:         packit.Environment{},
 					LaunchEnv:        packit.Environment{},
 					ProcessLaunchEnv: map[string]packit.Environment{},
@@ -110,12 +123,12 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 		}))
 
 		Expect(installProcess.ExecuteCall.Receives.WorkingDir).To(Equal(workingDir))
-		Expect(installProcess.ExecuteCall.Receives.TargetLayer.Path).To(Equal(filepath.Join(layersDir, pipenvinstall.PackagesLayerName)))
-		Expect(installProcess.ExecuteCall.Receives.CacheLayer.Path).To(Equal(filepath.Join(layersDir, pipenvinstall.CacheLayerName)))
+		Expect(installProcess.ExecuteCall.Receives.TargetLayer.Path).To(Equal(filepath.Join(layersDir, "packages")))
+		Expect(installProcess.ExecuteCall.Receives.CacheLayer.Path).To(Equal(filepath.Join(layersDir, "cache")))
 
-		Expect(entryResolver.MergeLayerTypesCall.Receives.Name).To(Equal(pipenvinstall.SitePackages))
+		Expect(entryResolver.MergeLayerTypesCall.Receives.Name).To(Equal("site-packages"))
 		Expect(entryResolver.MergeLayerTypesCall.Receives.Entries).To(Equal([]packit.BuildpackPlanEntry{
-			{Name: pipenvinstall.SitePackages},
+			{Name: "site-packages"},
 		}))
 
 		Expect(buffer.String()).To(ContainSubstring("Some Buildpack some-version"))
@@ -139,7 +152,7 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 				Plan: packit.BuildpackPlan{
 					Entries: []packit.BuildpackPlanEntry{
 						{
-							Name: pipenvinstall.SitePackages,
+							Name: "site-packages",
 						},
 					},
 				},
@@ -152,9 +165,14 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 			Expect(result).To(Equal(packit.BuildResult{
 				Layers: []packit.Layer{
 					{
-						Name:             pipenvinstall.PackagesLayerName,
-						Path:             filepath.Join(layersDir, pipenvinstall.PackagesLayerName),
-						SharedEnv:        packit.Environment{},
+						Name: "packages",
+						Path: filepath.Join(layersDir, "packages"),
+						SharedEnv: packit.Environment{
+							"PATH.delim":         ":",
+							"PATH.prepend":       filepath.Join("some-venv-dir", "bin"),
+							"PYTHONPATH.delim":   ":",
+							"PYTHONPATH.prepend": "some-site-packages-path",
+						},
 						BuildEnv:         packit.Environment{},
 						LaunchEnv:        packit.Environment{},
 						ProcessLaunchEnv: map[string]packit.Environment{},
@@ -195,7 +213,7 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 				Plan: packit.BuildpackPlan{
 					Entries: []packit.BuildpackPlanEntry{
 						{
-							Name: pipenvinstall.SitePackages,
+							Name: "site-packages",
 						},
 					},
 				},
@@ -208,9 +226,15 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 			Expect(result).To(Equal(packit.BuildResult{
 				Layers: []packit.Layer{
 					{
-						Name:             pipenvinstall.PackagesLayerName,
-						Path:             filepath.Join(layersDir, pipenvinstall.PackagesLayerName),
-						SharedEnv:        packit.Environment{},
+						Name: "packages",
+						Path: filepath.Join(layersDir, "packages"),
+						SharedEnv: packit.Environment{
+							"PATH.delim":         ":",
+							"PATH.prepend":       filepath.Join("some-venv-dir", "bin"),
+							"PYTHONPATH.delim":   ":",
+							"PYTHONPATH.prepend": "some-site-packages-path",
+						},
+
 						BuildEnv:         packit.Environment{},
 						LaunchEnv:        packit.Environment{},
 						ProcessLaunchEnv: map[string]packit.Environment{},
@@ -223,8 +247,8 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 						},
 					},
 					{
-						Name:             pipenvinstall.CacheLayerName,
-						Path:             filepath.Join(layersDir, pipenvinstall.CacheLayerName),
+						Name:             "cache",
+						Path:             filepath.Join(layersDir, "cache"),
 						SharedEnv:        packit.Environment{},
 						BuildEnv:         packit.Environment{},
 						LaunchEnv:        packit.Environment{},
@@ -296,5 +320,59 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 				Expect(err).To(MatchError(ContainSubstring("some-error")))
 			})
 		})
+
+		context("when venv directory locator returns an error", func() {
+			it.Before(func() {
+				venvDirLocator.LocateVenvDirCall.Returns.Err = errors.New("some-venv-error")
+			})
+
+			it("returns an error", func() {
+				_, err := build(packit.BuildContext{
+					WorkingDir: workingDir,
+					CNBPath:    cnbDir,
+					Stack:      "some-stack",
+					BuildpackInfo: packit.BuildpackInfo{
+						Name:    "Some Buildpack",
+						Version: "some-version",
+					},
+					Plan: packit.BuildpackPlan{
+						Entries: []packit.BuildpackPlanEntry{
+							{
+								Name: "site-packages",
+							},
+						},
+					},
+					Layers: packit.Layers{Path: layersDir},
+				})
+				Expect(err).To(MatchError(ContainSubstring("some-venv-error")))
+			})
+		})
+
+		context("when site packages process locator returns an error", func() {
+			it.Before(func() {
+				sitePackagesProcess.ExecuteCall.Returns.Err = errors.New("some-site-error")
+			})
+
+			it("returns an error", func() {
+				_, err := build(packit.BuildContext{
+					WorkingDir: workingDir,
+					CNBPath:    cnbDir,
+					Stack:      "some-stack",
+					BuildpackInfo: packit.BuildpackInfo{
+						Name:    "Some Buildpack",
+						Version: "some-version",
+					},
+					Plan: packit.BuildpackPlan{
+						Entries: []packit.BuildpackPlanEntry{
+							{
+								Name: "site-packages",
+							},
+						},
+					},
+					Layers: packit.Layers{Path: layersDir},
+				})
+				Expect(err).To(MatchError(ContainSubstring("some-site-error")))
+			})
+		})
 	})
 }

fakes/entry_resolver.go

@@ -8,7 +8,7 @@ import (
 
 type EntryResolver struct {
 	MergeLayerTypesCall struct {
-		sync.Mutex
+		mutex     sync.Mutex
 		CallCount int
 		Receives  struct {
 			Name    string
@@ -23,8 +23,8 @@ type EntryResolver struct {
 }
 
 func (f *EntryResolver) MergeLayerTypes(param1 string, param2 []packit.BuildpackPlanEntry) (bool, bool) {
-	f.MergeLayerTypesCall.Lock()
-	defer f.MergeLayerTypesCall.Unlock()
+	f.MergeLayerTypesCall.mutex.Lock()
+	defer f.MergeLayerTypesCall.mutex.Unlock()
 	f.MergeLayerTypesCall.CallCount++
 	f.MergeLayerTypesCall.Receives.Name = param1
 	f.MergeLayerTypesCall.Receives.Entries = param2

fakes/executable.go

@@ -8,7 +8,7 @@ import (
 
 type Executable struct {
 	ExecuteCall struct {
-		sync.Mutex
+		mutex     sync.Mutex
 		CallCount int
 		Receives  struct {
 			Execution pexec.Execution
@@ -21,8 +21,8 @@ type Executable struct {
 }
 
 func (f *Executable) Execute(param1 pexec.Execution) error {
-	f.ExecuteCall.Lock()
-	defer f.ExecuteCall.Unlock()
+	f.ExecuteCall.mutex.Lock()
+	defer f.ExecuteCall.mutex.Unlock()
 	f.ExecuteCall.CallCount++
 	f.ExecuteCall.Receives.Execution = param1
 	if f.ExecuteCall.Stub != nil {

fakes/install_process.go

@@ -8,7 +8,7 @@ import (
 
 type InstallProcess struct {
 	ExecuteCall struct {
-		sync.Mutex
+		mutex     sync.Mutex
 		CallCount int
 		Receives  struct {
 			WorkingDir  string
@@ -23,8 +23,8 @@ type InstallProcess struct {
 }
 
 func (f *InstallProcess) Execute(param1 string, param2 packit.Layer, param3 packit.Layer) error {
-	f.ExecuteCall.Lock()
-	defer f.ExecuteCall.Unlock()
+	f.ExecuteCall.mutex.Lock()
+	defer f.ExecuteCall.mutex.Unlock()
 	f.ExecuteCall.CallCount++
 	f.ExecuteCall.Receives.WorkingDir = param1
 	f.ExecuteCall.Receives.TargetLayer = param2

fakes/parser.go

@@ -4,7 +4,7 @@ import "sync"
 
 type Parser struct {
 	ParseVersionCall struct {
-		sync.Mutex
+		mutex     sync.Mutex
 		CallCount int
 		Receives  struct {
 			Path string
@@ -18,8 +18,8 @@ type Parser struct {
 }
 
 func (f *Parser) ParseVersion(param1 string) (string, error) {
-	f.ParseVersionCall.Lock()
-	defer f.ParseVersionCall.Unlock()
+	f.ParseVersionCall.mutex.Lock()
+	defer f.ParseVersionCall.mutex.Unlock()
 	f.ParseVersionCall.CallCount++
 	f.ParseVersionCall.Receives.Path = param1
 	if f.ParseVersionCall.Stub != nil {