From 5eb1c17fc09fadbc04bc1912e3ebbd845ab4dc53 Mon Sep 17 00:00:00 2001
From: Johannes Dillmann <j.dillmann@sap.com>
Date: Tue, 16 Apr 2024 11:26:38 +0200
Subject: [PATCH] Do not enforce presence of CNB_STACK_ID

Co-authored-by: Ralf Pannemans <ralf.pannemans@sap.com>
---
 build.go         |  6 +++---
 build_test.go    | 13 -------------
 detect.go        |  6 +++---
 detect_test.go   | 13 -------------
 generate.go      |  6 +++---
 generate_test.go | 13 -------------
 6 files changed, 9 insertions(+), 48 deletions(-)

diff --git a/build.go b/build.go
index 70b6032..5a5ab19 100644
--- a/build.go
+++ b/build.go
@@ -226,10 +226,10 @@ func Build(build BuildFunc, config Config) {
 	config.logger.Debugf("Buildpack Plan: %+v", ctx.Plan)
 
 	if ctx.StackID, ok = os.LookupEnv(EnvStackID); !ok {
-		config.exitHandler.Error(fmt.Errorf("CNB_STACK_ID not set"))
-		return
+		config.logger.Debug("CNB_STACK_ID not set")
+	} else {
+		config.logger.Debugf("Stack: %s", ctx.StackID)
 	}
-	config.logger.Debugf("Stack: %s", ctx.StackID)
 
 	result, err := build(ctx)
 	if err != nil {
diff --git a/build_test.go b/build_test.go
index db87978..7a951ca 100644
--- a/build_test.go
+++ b/build_test.go
@@ -253,19 +253,6 @@ version = "1.1.1"
 		}
 	})
 
-	it("doesn't receive CNB_STACK_ID", func() {
-		Expect(os.Unsetenv("CNB_STACK_ID")).To(Succeed())
-
-		libcnb.Build(buildFunc,
-			libcnb.NewConfig(
-				libcnb.WithArguments([]string{commandPath, layersPath, platformPath, buildpackPlanPath}),
-				libcnb.WithExitHandler(exitHandler),
-				libcnb.WithLogger(log.NewDiscard())),
-		)
-
-		Expect(exitHandler.Calls[0].Arguments.Get(0)).To(MatchError("CNB_STACK_ID not set"))
-	})
-
 	context("has a build environment", func() {
 		var ctx libcnb.BuildContext
 
diff --git a/detect.go b/detect.go
index b435d87..a5e044e 100644
--- a/detect.go
+++ b/detect.go
@@ -185,10 +185,10 @@ func Detect(detect DetectFunc, config Config) {
 	config.logger.Debugf("Platform Environment: %s", ctx.Platform.Environment)
 
 	if ctx.StackID, ok = os.LookupEnv(EnvStackID); !ok {
-		config.exitHandler.Error(fmt.Errorf("CNB_STACK_ID not set"))
-		return
+		config.logger.Debug("CNB_STACK_ID not set")
+	} else {
+		config.logger.Debugf("Stack: %s", ctx.StackID)
 	}
-	config.logger.Debugf("Stack: %s", ctx.StackID)
 
 	result, err := detect(ctx)
 	if err != nil {
diff --git a/detect_test.go b/detect_test.go
index 5cb065b..552631b 100644
--- a/detect_test.go
+++ b/detect_test.go
@@ -175,19 +175,6 @@ version = "1.1.1"
 		})
 	})
 
-	it("doesn't receive CNB_STACK_ID", func() {
-		Expect(os.Unsetenv("CNB_STACK_ID")).To(Succeed())
-
-		libcnb.Detect(detectFunc,
-			libcnb.NewConfig(
-				libcnb.WithArguments([]string{commandPath, platformPath, buildPlanPath}),
-				libcnb.WithExitHandler(exitHandler),
-				libcnb.WithLogger(log.NewDiscard())),
-		)
-
-		Expect(exitHandler.Calls[0].Arguments.Get(0)).To(MatchError("CNB_STACK_ID not set"))
-	})
-
 	context("errors if required env vars are not set", func() {
 		for _, e := range []string{"CNB_PLATFORM_DIR", "CNB_BUILD_PLAN_PATH"} {
 			// We need to do this assignment because of the way that spec binds variables
diff --git a/generate.go b/generate.go
index 69ee605..600b13c 100644
--- a/generate.go
+++ b/generate.go
@@ -179,10 +179,10 @@ func Generate(generate GenerateFunc, config Config) {
 	config.logger.Debugf("Buildpack Plan: %+v", ctx.Plan)
 
 	if ctx.StackID, ok = os.LookupEnv(EnvStackID); !ok {
-		config.exitHandler.Error(fmt.Errorf("CNB_STACK_ID not set"))
-		return
+		config.logger.Debug("CNB_STACK_ID not set")
+	} else {
+		config.logger.Debugf("Stack: %s", ctx.StackID)
 	}
-	config.logger.Debugf("Stack: %s", ctx.StackID)
 
 	result, err := generate(ctx)
 	if err != nil {
diff --git a/generate_test.go b/generate_test.go
index 925b99e..54a77d2 100644
--- a/generate_test.go
+++ b/generate_test.go
@@ -235,19 +235,6 @@ version = "1.1.1"
 		}
 	})
 
-	it("doesn't receive CNB_STACK_ID", func() {
-		Expect(os.Unsetenv("CNB_STACK_ID")).To(Succeed())
-
-		libcnb.Generate(generateFunc,
-			libcnb.NewConfig(
-				libcnb.WithArguments([]string{commandPath, outputPath, platformPath, buildpackPlanPath}),
-				libcnb.WithExitHandler(exitHandler),
-				libcnb.WithLogger(log.NewDiscard())),
-		)
-
-		Expect(exitHandler.Calls[0].Arguments.Get(0)).To(MatchError("CNB_STACK_ID not set"))
-	})
-
 	context("has a build environment", func() {
 		var ctx libcnb.GenerateContext