Conditional at Launch

Previously, a binding was required at build time in order to contribute the
layers for the Stackdriver components.  We've started to think that requiring
a binding during build is too onerous a restriction and instead environment
variables should be used to indicate that a dependency should be contributed.
The knock-on effect of this change is that we have to move a lot more of the
conditional logic out to launch time including ensuring that if the binding
doesn't exist _nothing_ is contributed.  This change makes those updates to
the buildpack's behavior.

In addition, this change also includes an update that enables the buildpack to
determine if the application is running in GCP by detecting the metadata
server.  In this case, no binding is required at launch time either as the
credentials typically provided by the binding are instead provided by the
metadata server.

Finally, this includes a fix where the provided build plan wasn't anywhere
near exhaustive for combinations that a user need when using the buildpack.

Signed-off-by: Ben Hale <[email protected]>

README.md

@@ -4,8 +4,8 @@ The Paketo Google Stackdriver Buildpack is a Cloud Native Buildpack that contrib
 ## Behavior
 This buildpack will participate if any of the following conditions are met
 
-* A binding exists with `type` of `StackdriverDebugger`
-* A binding exists with `type` of `StackdriverProfiler`
+* `$BP_GOOGLE_STACKDRIVER_DEBUGGER_ENABLED` is set
+* `$BP_GOOGLE_STACKDRIVER_PROFILER_ENABLED` is set
 
 The buildpack will do the following for Java applications:
 

buildpack.toml

@@ -42,6 +42,16 @@ name        = "BPL_GOOGLE_STACKDRIVER_VERSION"
 description = "the version of the application"
 launch      = true
 
+[[metadata.configurations]]
+name        = "BP_GOOGLE_STACKDRIVER_DEBUGGER_ENABLED"
+description = "whether to contribute Google Stackdriver Debugger support"
+build       = true
+
+[[metadata.configurations]]
+name        = "BP_GOOGLE_STACKDRIVER_PROFILER_ENABLED"
+description = "whether to contribute Google Stackdriver Profiler support"
+build       = true
+
 [[metadata.dependencies]]
 id      = "google-stackdriver-debugger-java"
 name    = "Google Stackdriver Debugger Java Agent"

cmd/helper/main.go

@@ -21,6 +21,7 @@ import (
 	"os"
 
 	"github.com/buildpacks/libcnb"
+
 	"github.com/paketo-buildpacks/libpak/bard"
 	"github.com/paketo-buildpacks/libpak/sherpa"
 
@@ -29,23 +30,24 @@ import (
 
 func main() {
 	sherpa.Execute(func() error {
-		var (
-			err error
-			l   = bard.NewLogger(os.Stdout)
-			c   = helper.Credentials{Logger: l}
-			d   = helper.JavaDebugger{Logger: l}
-			p   = helper.JavaProfiler{Logger: l}
-		)
-
-		c.Bindings, err = libcnb.NewBindingsFromEnvironment()
+		l := bard.NewLogger(os.Stdout)
+
+		a, err := os.Getwd()
+		if err != nil {
+			return fmt.Errorf("unable to read working directory\n%w", err)
+		}
+
+		b, err := libcnb.NewBindingsFromEnvironment()
 		if err != nil {
 			return fmt.Errorf("unable to read bindings from environment\n%w", err)
 		}
 
 		return sherpa.Helpers(map[string]sherpa.ExecD{
-			"credentials":   c,
-			"java-debugger": d,
-			"java-profiler": p,
+			"credentials":     helper.Credentials{Bindings: b, Logger: l},
+			"java-debugger":   helper.JavaDebugger{Bindings: b, Logger: l, InGCP: helper.InGCP},
+			"java-profiler":   helper.JavaProfiler{Bindings: b, Logger: l, InGCP: helper.InGCP},
+			"nodejs-debugger": helper.NodeJSDebugger{ApplicationPath: a, Bindings: b, Logger: l, InGCP: helper.InGCP},
+			"nodejs-profiler": helper.NodeJSProfiler{ApplicationPath: a, Bindings: b, Logger: l, InGCP: helper.InGCP},
 		})
 	})
 }

go.mod

@@ -9,3 +9,5 @@ require (
 	github.com/sclevine/spec v1.4.0
 	github.com/stretchr/testify v1.6.1
 )
+
+replace github.com/paketo-buildpacks/libpak => ../../paketo-buildpacks/libpak

helper/credentials.go

@@ -17,9 +17,8 @@
 package helper
 
 import (
-	"fmt"
-
 	"github.com/buildpacks/libcnb"
+
 	"github.com/paketo-buildpacks/libpak/bard"
 	"github.com/paketo-buildpacks/libpak/bindings"
 )
@@ -30,19 +29,10 @@ type Credentials struct {
 }
 
 func (c Credentials) Execute() (map[string]string, error) {
-	if b, ok, err := bindings.ResolveOne(c.Bindings, bindings.OfType("StackdriverDebugger")); err != nil {
-		return nil, fmt.Errorf("unable to resolve binding StackdriverDebugger\n%w", err)
-	} else if ok {
-		if p, ok := b.SecretFilePath("ApplicationCredentials"); ok {
-			c.Logger.Info("Configuring Google application credentials")
-			return map[string]string{"GOOGLE_APPLICATION_CREDENTIALS": p}, nil
-		}
-	}
+	b := bindings.Resolve(c.Bindings, bindings.Or(bindings.OfType("StackdriverDebugger"), bindings.OfType("StackdriverProfiler")))
 
-	if b, ok, err := bindings.ResolveOne(c.Bindings, bindings.OfType("StackdriverProfiler")); err != nil {
-		return nil, fmt.Errorf("unable to resolve binding StackdriverProfiler\n%w", err)
-	} else if ok {
-		if p, ok := b.SecretFilePath("ApplicationCredentials"); ok {
+	if len(b) > 0 {
+		if p, ok := b[0].SecretFilePath("ApplicationCredentials"); ok {
 			c.Logger.Info("Configuring Google application credentials")
 			return map[string]string{"GOOGLE_APPLICATION_CREDENTIALS": p}, nil
 		}

helper/credentials_test.go

@@ -34,7 +34,7 @@ func testCredentials(t *testing.T, context spec.G, it spec.S) {
 	)
 
 	it("does not contribute properties if no binding exists", func() {
-		Expect(c.Execute()).To(BeZero())
+		Expect(c.Execute()).To(BeNil())
 	})
 
 	it("contributes credentials if debugger binding exists", func() {

helper/in_gcp.go

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2018-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package helper
+
+import (
+	"net/http"
+)
+
+// InGCP detects whether the application is running within GCP.  Detection is based on the existence of the metadata
+// server as defined in https://cloud.google.com/compute/docs/storing-retrieving-metadata#querying.
+func InGCP() bool {
+	req, err := http.NewRequest("GET", "http://metadata.google.internal/computeMetadata/v1/", nil)
+	if err != nil {
+		return false
+	}
+	req.Header.Add("Metadata-Flavor", "Google")
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return false
+	}
+	defer resp.Body.Close()
+
+	return true
+}

helper/init_test.go

@@ -28,5 +28,7 @@ func TestUnit(t *testing.T) {
 	suite("Credentials", testCredentials)
 	suite("JavaDebugger", testJavaDebugger)
 	suite("JavaProfiler", testJavaProfiler)
+	suite("NodeJSDebugger", testNodeJSDebugger)
+	suite("NodeJSProfiler", testNodeJSProfiler)
 	suite.Run(t)
 }

helper/java_debugger.go

@@ -19,42 +19,61 @@ package helper
 import (
 	"fmt"
 	"os"
-	"strings"
+
+	"github.com/buildpacks/libcnb"
 
 	"github.com/paketo-buildpacks/libpak/bard"
+	"github.com/paketo-buildpacks/libpak/bindings"
+	"github.com/paketo-buildpacks/libpak/sherpa"
 )
 
 type JavaDebugger struct {
-	Logger bard.Logger
+	Bindings libcnb.Bindings
+	Logger   bard.Logger
+	InGCP    func() bool
 }
 
 func (j JavaDebugger) Execute() (map[string]string, error) {
-	module, ok := os.LookupEnv("BPL_GOOGLE_STACKDRIVER_MODULE")
-	if !ok {
-		module = "default-module"
+	if !j.configured() {
+		return nil, nil
 	}
 
+	module := sherpa.GetEnvWithDefault("BPL_GOOGLE_STACKDRIVER_MODULE", "default-module")
 	version := os.Getenv("BPL_GOOGLE_STACKDRIVER_VERSION")
 
-	var values []string
-	if s, ok := os.LookupEnv("JAVA_TOOL_OPTIONS"); ok {
-		values = append(values, s)
+	message := fmt.Sprintf("Google Stackdriver Debugger enabled for %s", module)
+	if version != "" {
+		message = fmt.Sprintf("%s:%s", message, version)
+	}
+	j.Logger.Info(message)
+
+	agentPath, err := sherpa.GetEnvRequired("BPI_GOOGLE_STACKDRIVER_DEBUGGER_JAVA_AGENT_PATH")
+	if err != nil {
+		return nil, err
 	}
 
-	values = append(values,
+	var agent []string
+	agent = append(agent,
+		fmt.Sprintf("-agentpath:%s=--logtostderr=1", agentPath),
 		"-Dcom.google.cdbg.auth.serviceaccount.enable=true",
 		fmt.Sprintf("-Dcom.google.cdbg.module=%s", module),
 	)
 
 	if version != "" {
-		values = append(values, fmt.Sprintf("-Dcom.google.cdbg.version=%s", version))
+		agent = append(agent, fmt.Sprintf("-Dcom.google.cdbg.version=%s", version))
 	}
 
-	message := fmt.Sprintf("Google Stackdriver Debugger enabled for %s", module)
-	if version != "" {
-		message = fmt.Sprintf("%s:%s", message, version)
+	return map[string]string{
+		"JAVA_TOOL_OPTIONS": sherpa.AppendToEnvVar("JAVA_TOOL_OPTIONS", " ", agent...),
+	}, nil
+}
+
+func (j JavaDebugger) configured() bool {
+	if _, ok, err := bindings.ResolveOne(j.Bindings, bindings.OfType("StackdriverDebugger")); err != nil {
+		return false
+	} else if ok {
+		return true
 	}
-	j.Logger.Info(message)
 
-	return map[string]string{"JAVA_TOOL_OPTIONS": strings.Join(values, " ")}, nil
+	return j.InGCP()
 }

helper/java_debugger_test.go

@@ -20,6 +20,7 @@ import (
 	"os"
 	"testing"
 
+	"github.com/buildpacks/libcnb"
 	. "github.com/onsi/gomega"
 	"github.com/sclevine/spec"
 
@@ -30,60 +31,104 @@ func testJavaDebugger(t *testing.T, context spec.G, it spec.S) {
 	var (
 		Expect = NewWithT(t).Expect
 
-		j helper.JavaDebugger
+		j = helper.JavaDebugger{
+			InGCP: func() bool { return false },
+		}
 	)
 
-	it("uses defaults", func() {
-		Expect(j.Execute()).To(Equal(map[string]string{
-			"JAVA_TOOL_OPTIONS": "-Dcom.google.cdbg.auth.serviceaccount.enable=true -Dcom.google.cdbg.module=default-module",
-		}))
+	it("does nothing without binding or GCP", func() {
+		Expect(j.Execute()).To(BeNil())
 	})
 
-	context("$BPL_GOOGLE_STACKDRIVER_MODULE", func() {
+	context("with binding", func() {
 		it.Before(func() {
-			Expect(os.Setenv("BPL_GOOGLE_STACKDRIVER_MODULE", "test-module")).To(Succeed())
+			j.Bindings = libcnb.Bindings{libcnb.Binding{Type: "StackdriverDebugger"}}
 		})
 
-		it.After(func() {
-			Expect(os.Unsetenv("BPL_GOOGLE_STACKDRIVER_MODULE")).To(Succeed())
+		it("fails without $BPI_GOOGLE_STACKDRIVER_DEBUGGER_JAVA_AGENT_PATH", func() {
+			_, err := j.Execute()
+			Expect(err).To(MatchError("$BPI_GOOGLE_STACKDRIVER_DEBUGGER_JAVA_AGENT_PATH must be set"))
 		})
 
-		it("uses configured module", func() {
-			Expect(j.Execute()).To(Equal(map[string]string{
-				"JAVA_TOOL_OPTIONS": "-Dcom.google.cdbg.auth.serviceaccount.enable=true -Dcom.google.cdbg.module=test-module",
-			}))
+		context("$BPI_GOOGLE_STACKDRIVER_DEBUGGER_JAVA_AGENT_PATH", func() {
+
+			it.Before(func() {
+				Expect(os.Setenv("BPI_GOOGLE_STACKDRIVER_DEBUGGER_JAVA_AGENT_PATH", "test-path")).To(Succeed())
+			})
+
+			it.After(func() {
+				Expect(os.Unsetenv("BPI_GOOGLE_STACKDRIVER_DEBUGGER_JAVA_AGENT_PATH")).To(Succeed())
+			})
+
+			it("uses defaults", func() {
+				Expect(j.Execute()).To(Equal(map[string]string{
+					"JAVA_TOOL_OPTIONS": "-agentpath:test-path=--logtostderr=1 -Dcom.google.cdbg.auth.serviceaccount.enable=true -Dcom.google.cdbg.module=default-module",
+				}))
+			})
+
+			context("$BPL_GOOGLE_STACKDRIVER_MODULE", func() {
+				it.Before(func() {
+					Expect(os.Setenv("BPL_GOOGLE_STACKDRIVER_MODULE", "test-module")).To(Succeed())
+				})
+
+				it.After(func() {
+					Expect(os.Unsetenv("BPL_GOOGLE_STACKDRIVER_MODULE")).To(Succeed())
+				})
+
+				it("uses configured module", func() {
+					Expect(j.Execute()).To(Equal(map[string]string{
+						"JAVA_TOOL_OPTIONS": "-agentpath:test-path=--logtostderr=1 -Dcom.google.cdbg.auth.serviceaccount.enable=true -Dcom.google.cdbg.module=test-module",
+					}))
+				})
+			})
+
+			context("$BPL_GOOGLE_STACKDRIVER_VERSION", func() {
+				it.Before(func() {
+					Expect(os.Setenv("BPL_GOOGLE_STACKDRIVER_VERSION", "test-version")).To(Succeed())
+				})
+
+				it.After(func() {
+					Expect(os.Unsetenv("BPL_GOOGLE_STACKDRIVER_VERSION")).To(Succeed())
+				})
+
+				it("uses configured version", func() {
+					Expect(j.Execute()).To(Equal(map[string]string{
+						"JAVA_TOOL_OPTIONS": "-agentpath:test-path=--logtostderr=1 -Dcom.google.cdbg.auth.serviceaccount.enable=true -Dcom.google.cdbg.module=default-module -Dcom.google.cdbg.version=test-version",
+					}))
+				})
+			})
+
+			context("$JAVA_TOOL_OPTIONS", func() {
+				it.Before(func() {
+					Expect(os.Setenv("JAVA_TOOL_OPTIONS", "test-java-tool-options")).To(Succeed())
+				})
+
+				it.After(func() {
+					Expect(os.Unsetenv("JAVA_TOOL_OPTIONS")).To(Succeed())
+				})
+
+				it("uses configured JAVA_TOOL_OPTIONS", func() {
+					Expect(j.Execute()).To(Equal(map[string]string{
+						"JAVA_TOOL_OPTIONS": "test-java-tool-options -agentpath:test-path=--logtostderr=1 -Dcom.google.cdbg.auth.serviceaccount.enable=true -Dcom.google.cdbg.module=default-module",
+					}))
+				})
+			})
 		})
 	})
 
-	context("$BPL_GOOGLE_STACKDRIVER_VERSION", func() {
+	context("with GCP", func() {
 		it.Before(func() {
-			Expect(os.Setenv("BPL_GOOGLE_STACKDRIVER_VERSION", "test-version")).To(Succeed())
-		})
-
-		it.After(func() {
-			Expect(os.Unsetenv("BPL_GOOGLE_STACKDRIVER_VERSION")).To(Succeed())
-		})
+			j.InGCP = func() bool { return true }
 
-		it("uses configured version", func() {
-			Expect(j.Execute()).To(Equal(map[string]string{
-				"JAVA_TOOL_OPTIONS": "-Dcom.google.cdbg.auth.serviceaccount.enable=true -Dcom.google.cdbg.module=default-module -Dcom.google.cdbg.version=test-version",
-			}))
-		})
-	})
-
-	context("$JAVA_TOOL_OPTIONS", func() {
-		it.Before(func() {
-			Expect(os.Setenv("JAVA_TOOL_OPTIONS", "test-java-tool-options")).To(Succeed())
+			Expect(os.Setenv("BPI_GOOGLE_STACKDRIVER_DEBUGGER_JAVA_AGENT_PATH", "test-path")).To(Succeed())
 		})
 
 		it.After(func() {
-			Expect(os.Unsetenv("JAVA_TOOL_OPTIONS")).To(Succeed())
+			Expect(os.Unsetenv("BPI_GOOGLE_STACKDRIVER_DEBUGGER_JAVA_AGENT_PATH")).To(Succeed())
 		})
 
-		it("uses configured JAVA_TOOL_OPTIONS", func() {
-			Expect(j.Execute()).To(Equal(map[string]string{
-				"JAVA_TOOL_OPTIONS": "test-java-tool-options -Dcom.google.cdbg.auth.serviceaccount.enable=true -Dcom.google.cdbg.module=default-module",
-			}))
+		it("configures environment", func() {
+			Expect(j.Execute()).NotTo(BeNil())
 		})
 	})
 }