Requiring python during build time in case is not available on the build image (#1318)

* feat: requiring cpython in non rhel distros

* fix: integration tests to include proeprly python

* fix: offline test for cpython

* Update integration/reuse_layer_rebuild_test.go

remove comment

---------

Co-authored-by: Jerico Pena <jericop@users.noreply.github.com>

Author: pacostas

constants.go

@@ -1,8 +1,9 @@
 package nodeengine
 
 const (
-	Node = "node"
-	Npm  = "npm"
+	Node    = "node"
+	Npm     = "npm"
+	Cpython = "cpython"
 
 	DepKey             = "dependency-sha"
 	BuildKey           = "build"

detect.go

@@ -2,6 +2,7 @@ package nodeengine
 
 import (
 	"os"
+	"os/exec"
 	"path/filepath"
 
 	"github.com/paketo-buildpacks/packit/v2"
@@ -16,6 +17,8 @@ type VersionParser interface {
 type BuildPlanMetadata struct {
 	Version       string `toml:"version"`
 	VersionSource string `toml:"version-source"`
+	Build         bool   `toml:"build"`
+	Launch        bool   `toml:"launch"`
 }
 
 func Detect(nvmrcParser, nodeVersionParser VersionParser) packit.DetectFunc {
@@ -80,6 +83,20 @@ func Detect(nvmrcParser, nodeVersionParser VersionParser) packit.DetectFunc {
 			})
 		}
 
+		targetOs := os.Getenv("CNB_TARGET_DISTRO_NAME")
+		_, pythonNotFound := exec.LookPath("python")
+
+		installPython := (targetOs != "rhel" && pythonNotFound != nil)
+		if installPython {
+			requirements = append(requirements, packit.BuildPlanRequirement{
+				Name: Cpython,
+				Metadata: BuildPlanMetadata{
+					Build:  true,
+					Launch: false,
+				},
+			})
+		}
+
 		return packit.DetectResult{
 			Plan: packit.BuildPlan{
 				Provides: []packit.BuildPlanProvision{

integration.json

@@ -1,6 +1,8 @@
 {
   "build-plan": "github.com/paketo-community/build-plan",
   "builders": [
-    "index.docker.io/paketobuildpacks/builder-jammy-buildpackless-base:latest"
-  ]
+    "index.docker.io/paketobuildpacks/builder-jammy-buildpackless-base:latest",
+    "index.docker.io/paketobuildpacks/ubuntu-noble-builder-buildpackless:latest"
+  ],
+  "cpython": "github.com/paketo-buildpacks/cpython"
 }

integration/init_test.go

@@ -29,6 +29,10 @@ var settings struct {
 		Processes struct {
 			Online string
 		}
+		Cpython struct {
+			Online  string
+			Offline string
+		}
 	}
 
 	Buildpack struct {
@@ -38,6 +42,7 @@ var settings struct {
 
 	Config struct {
 		BuildPlan string `json:"build-plan"`
+		Cpython   string `json:"cpython"`
 	}
 }
 
@@ -73,6 +78,15 @@ func TestIntegration(t *testing.T) {
 		Execute(root)
 	Expect(err).NotTo(HaveOccurred())
 
+	settings.Buildpacks.Cpython.Online, err = buildpackStore.Get.
+		Execute(settings.Config.Cpython)
+	Expect(err).ToNot(HaveOccurred())
+
+	settings.Buildpacks.Cpython.Offline, err = buildpackStore.Get.
+		WithOfflineDependencies().
+		Execute(settings.Config.Cpython)
+	Expect(err).ToNot(HaveOccurred())
+
 	tmpBuildpackDir, err := os.MkdirTemp("", "node-engine-outdated-deps")
 	Expect(err).NotTo(HaveOccurred())
 

integration/inspector_test.go

@@ -52,6 +52,7 @@ func testInspector(t *testing.T, context spec.G, it spec.S) {
 		image, logs, err = pack.WithNoColor().Build.
 			WithPullPolicy("never").
 			WithBuildpacks(
+				settings.Buildpacks.Cpython.Online,
 				settings.Buildpacks.NodeEngine.Online,
 				settings.Buildpacks.Processes.Online,
 			).

integration/offline_test.go

@@ -56,6 +56,7 @@ func testOffline(t *testing.T, context spec.G, it spec.S) {
 			image, logs, err = pack.WithNoColor().Build.
 				WithPullPolicy("never").
 				WithBuildpacks(
+					settings.Buildpacks.Cpython.Offline,
 					settings.Buildpacks.NodeEngine.Offline,
 					settings.Buildpacks.BuildPlan.Online,
 				).

integration/openssl_test.go

@@ -67,6 +67,7 @@ func testOpenSSL(t *testing.T, context spec.G, it spec.S) {
 
 				image, logs, err = pack.WithNoColor().Build.
 					WithBuildpacks(
+						settings.Buildpacks.Cpython.Online,
 						settings.Buildpacks.NodeEngine.Online,
 						settings.Buildpacks.BuildPlan.Online,
 					).
@@ -106,6 +107,7 @@ func testOpenSSL(t *testing.T, context spec.G, it spec.S) {
 
 				image, logs, err = pack.WithNoColor().Build.
 					WithBuildpacks(
+						settings.Buildpacks.Cpython.Online,
 						settings.Buildpacks.NodeEngine.Online,
 						settings.Buildpacks.BuildPlan.Online,
 					).

integration/optimize_memory_test.go

@@ -53,6 +53,7 @@ func testOptimizeMemory(t *testing.T, context spec.G, it spec.S) {
 		image, logs, err = pack.WithNoColor().Build.
 			WithPullPolicy("never").
 			WithBuildpacks(
+				settings.Buildpacks.Cpython.Online,
 				settings.Buildpacks.NodeEngine.Online,
 				settings.Buildpacks.Processes.Online,
 			).

integration/project_path_test.go

@@ -60,6 +60,7 @@ func testProjectPath(t *testing.T, context spec.G, it spec.S) {
 			image, logs, err = pack.WithNoColor().Build.
 				WithPullPolicy("never").
 				WithBuildpacks(
+					settings.Buildpacks.Cpython.Online,
 					settings.Buildpacks.NodeEngine.Online,
 					settings.Buildpacks.BuildPlan.Online,
 				).

integration/provides_test.go

@@ -55,6 +55,7 @@ func testProvides(t *testing.T, context spec.G, it spec.S) {
 			image, logs, err = pack.WithNoColor().Build.
 				WithPullPolicy("never").
 				WithBuildpacks(
+					settings.Buildpacks.Cpython.Online,
 					settings.Buildpacks.NodeEngine.Online,
 					settings.Buildpacks.BuildPlan.Online,
 				).