feat: force order of plan entries processing (#59)

From time to time, the build function receives the
plan entries out of order. This implementation will
ensure that pip is installed before pipenv or poetry.

Author: sgaist

build.go

@@ -34,72 +34,78 @@ func Build(
 
 		var results []packit.BuildResult
 
-		for _, entry := range context.Plan.Entries {
-			logger.Title("Handling %s", entry.Name)
-			parameters, ok := buildParameters[entry.Name]
-
-			if !ok {
-				return packit.BuildResult{}, packit.Fail.WithMessage("missing parameters for: %s", entry.Name)
-			}
-
-			switch entry.Name {
-			case pip.Pip:
-				result, err := pip.Build(
-					parameters.(pip.PipBuildParameters),
-					commonBuildParameters,
-				)(context)
-
-				if err != nil {
-					return packit.BuildResult{}, err
+		orderedInstallers := []string{pip.Pip, pipenv.Pipenv, poetry.PoetryDependency, miniconda.Conda, uv.Uv}
+
+		for _, installer := range orderedInstallers {
+			for _, entry := range context.Plan.Entries {
+				if entry.Name == installer {
+					logger.Title("Handling %s", entry.Name)
+					parameters, ok := buildParameters[entry.Name]
+
+					if !ok {
+						return packit.BuildResult{}, packit.Fail.WithMessage("missing parameters for: %s", entry.Name)
+					}
+
+					switch entry.Name {
+					case pip.Pip:
+						result, err := pip.Build(
+							parameters.(pip.PipBuildParameters),
+							commonBuildParameters,
+						)(context)
+
+						if err != nil {
+							return packit.BuildResult{}, err
+						}
+						results = append(results, result)
+
+					case pipenv.Pipenv:
+						result, err := pipenv.Build(
+							parameters.(pipenv.PipEnvBuildParameters),
+							commonBuildParameters,
+						)(context)
+
+						if err != nil {
+							return packit.BuildResult{}, err
+						}
+						results = append(results, result)
+
+					case poetry.PoetryDependency:
+						result, err := poetry.Build(
+							parameters.(poetry.PoetryBuildParameters),
+							commonBuildParameters,
+						)(context)
+
+						if err != nil {
+							return packit.BuildResult{}, err
+						}
+						results = append(results, result)
+
+					case miniconda.Conda:
+						result, err := miniconda.Build(
+							parameters.(miniconda.CondaBuildParameters),
+							commonBuildParameters,
+						)(context)
+
+						if err != nil {
+							return packit.BuildResult{}, err
+						}
+						results = append(results, result)
+
+					case uv.Uv:
+						result, err := uv.Build(
+							parameters.(uv.UvBuildParameters),
+							commonBuildParameters,
+						)(context)
+
+						if err != nil {
+							return packit.BuildResult{}, err
+						}
+						results = append(results, result)
+
+					default:
+						return packit.BuildResult{}, packit.Fail.WithMessage("unknown plan: %s", entry.Name)
+					}
 				}
-				results = append(results, result)
-
-			case pipenv.Pipenv:
-				result, err := pipenv.Build(
-					parameters.(pipenv.PipEnvBuildParameters),
-					commonBuildParameters,
-				)(context)
-
-				if err != nil {
-					return packit.BuildResult{}, err
-				}
-				results = append(results, result)
-
-			case miniconda.Conda:
-				result, err := miniconda.Build(
-					parameters.(miniconda.CondaBuildParameters),
-					commonBuildParameters,
-				)(context)
-
-				if err != nil {
-					return packit.BuildResult{}, err
-				}
-				results = append(results, result)
-
-			case poetry.PoetryDependency:
-				result, err := poetry.Build(
-					parameters.(poetry.PoetryBuildParameters),
-					commonBuildParameters,
-				)(context)
-
-				if err != nil {
-					return packit.BuildResult{}, err
-				}
-				results = append(results, result)
-
-			case uv.Uv:
-				result, err := uv.Build(
-					parameters.(uv.UvBuildParameters),
-					commonBuildParameters,
-				)(context)
-
-				if err != nil {
-					return packit.BuildResult{}, err
-				}
-				results = append(results, result)
-
-			default:
-				return packit.BuildResult{}, packit.Fail.WithMessage("unknown plan: %s", entry.Name)
 			}
 		}
 

build_test.go

@@ -350,6 +350,32 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 				},
 				1,
 			},
+			{
+				packit.BuildpackPlan{
+					Entries: []packit.BuildpackPlanEntry{
+						{
+							Name: pip.Pip,
+						},
+						{
+							Name: pipenv.Pipenv,
+						},
+					},
+				},
+				3,
+			},
+			{
+				packit.BuildpackPlan{
+					Entries: []packit.BuildpackPlanEntry{
+						{
+							Name: pip.Pip,
+						},
+						{
+							Name: poetry.PoetryDependency,
+						},
+					},
+				},
+				3,
+			},
 		}
 		Expect(os.WriteFile(filepath.Join(workingDir, "x.py"), []byte{}, os.ModePerm)).To(Succeed())
 		Expect(os.WriteFile(filepath.Join(workingDir, "pyproject.toml"), []byte(""), 0755)).To(Succeed())
@@ -368,6 +394,42 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 		}
 	})
 
+	it("runs the build process and returns layers in expected order", func() {
+		orderTestPlans := []packit.BuildpackPlan{
+			{
+				Entries: []packit.BuildpackPlanEntry{
+					{
+						Name: pipenv.Pipenv,
+					},
+					{
+						Name: pip.Pip,
+					},
+				},
+			},
+			{
+				Entries: []packit.BuildpackPlanEntry{
+					{
+						Name: poetry.PoetryDependency,
+					},
+					{
+						Name: pip.Pip,
+					},
+				},
+			},
+		}
+		for _, testPlan := range orderTestPlans {
+			logger.Detail("Doing: %s", testPlan)
+			buildContext.Plan = testPlan
+			result, err := build(buildContext)
+			Expect(err).NotTo(HaveOccurred())
+
+			layers := result.Layers
+			Expect(layers[0].Name).To(Equal(pip.Pip))
+			// Pip adds two layers
+			Expect(layers[2].Name).To(Equal(testPlan.Entries[0].Name))
+		}
+	})
+
 	it("fails if packager parameters is missing", func() {
 		packagerParameters := map[string]pythoninstallers.PackagerParameters{}