Implementation of RFC 0001 (#6)

* Bootsrapped files and failing integration tests

* working detect

Signed-off-by: Arjun Sreedharan <[email protected]>

* build executable

Signed-off-by: Arjun Sreedharan <[email protected]>

* Add tests for graceful shutdown

Update README and CODEOWNERS

Signed-off-by: Sophie Wigmore <[email protected]>

Co-authored-by: Arjun Sreedharan <[email protected]>

.github/.syncignore

@@ -0,0 +1 @@
+CODEOWNERS

.github/CODEOWNERS

@@ -0,0 +1 @@
+* @paketo-buildpacks/nodejs-maintainers

.gitignore

@@ -0,0 +1,2 @@
+/.bin
+/.build

README.md

@@ -1 +1,20 @@
 # Yarn Start Cloud Native Buildpack
+
+## `gcr.io/paketo-community/yarn-install`
+
+The Yarn Start CNB sets the start command for the given application.
+
+## Integration
+
+This CNB writes a command, so there's currently no scenario we can
+imagine that you would need to require it as dependency.
+
+To package this buildpack for consumption:
+```
+$ ./scripts/package.sh
+```
+This builds the buildpack's source using GOOS=linux by default. You can supply another value as the first argument to package.sh.
+
+## `buildpack.yml` Configurations
+
+There are no extra configurations for this buildpack based on `buildpack.yml`.

build.go

@@ -0,0 +1,28 @@
+package yarnstart
+
+import (
+	"github.com/paketo-buildpacks/packit"
+	"github.com/paketo-buildpacks/packit/scribe"
+)
+
+func Build(logger scribe.Logger) packit.BuildFunc {
+	return func(context packit.BuildContext) (packit.BuildResult, error) {
+		logger.Title("%s %s", context.BuildpackInfo.Name, context.BuildpackInfo.Version)
+
+		logger.Process("Writing start command")
+		command := "tini -g -- yarn start"
+		logger.Subprocess(command)
+
+		return packit.BuildResult{
+			Plan: packit.BuildpackPlan{
+				Entries: []packit.BuildpackPlanEntry{},
+			},
+			Processes: []packit.Process{
+				{
+					Type:    "web",
+					Command: command,
+				},
+			},
+		}, nil
+	}
+}

build_test.go

@@ -0,0 +1,80 @@
+package yarnstart_test
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/paketo-buildpacks/packit"
+	"github.com/paketo-buildpacks/packit/scribe"
+	yarnstart "github.com/paketo-buildpacks/yarn-start"
+	"github.com/sclevine/spec"
+
+	. "github.com/onsi/gomega"
+)
+
+func testBuild(t *testing.T, context spec.G, it spec.S) {
+	var (
+		Expect = NewWithT(t).Expect
+
+		layersDir  string
+		workingDir string
+		cnbDir     string
+		buffer     *bytes.Buffer
+
+		build packit.BuildFunc
+	)
+
+	it.Before(func() {
+		var err error
+		layersDir, err = ioutil.TempDir("", "layers")
+		Expect(err).NotTo(HaveOccurred())
+
+		cnbDir, err = ioutil.TempDir("", "cnb")
+		Expect(err).NotTo(HaveOccurred())
+
+		workingDir, err = ioutil.TempDir("", "working-dir")
+		Expect(err).NotTo(HaveOccurred())
+
+		buffer = bytes.NewBuffer(nil)
+		logger := scribe.NewLogger(buffer)
+
+		build = yarnstart.Build(logger)
+	})
+
+	it.After(func() {
+		Expect(os.RemoveAll(layersDir)).To(Succeed())
+		Expect(os.RemoveAll(cnbDir)).To(Succeed())
+		Expect(os.RemoveAll(workingDir)).To(Succeed())
+	})
+
+	it("returns a result that builds correctly", func() {
+		result, 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{},
+			},
+			Layers: packit.Layers{Path: layersDir},
+		})
+		Expect(err).NotTo(HaveOccurred())
+
+		Expect(result).To(Equal(packit.BuildResult{
+			Plan: packit.BuildpackPlan{
+				Entries: []packit.BuildpackPlanEntry{},
+			},
+			Processes: []packit.Process{
+				{
+					Type:    "web",
+					Command: "tini -g -- yarn start",
+				},
+			},
+		}))
+	})
+}

buildpack.toml

@@ -0,0 +1,15 @@
+api = "0.2"
+
+[buildpack]
+  id = "paketo-buildpacks/yarn-start"
+  name = "Yarn-Start Buildpack"
+
+[[stacks]]
+  id = "io.buildpacks.stacks.bionic"
+
+[[stacks]]
+  id = "org.cloudfoundry.stacks.cflinuxfs3"
+
+[metadata]
+  include_files = ["bin/run","bin/build","bin/detect","buildpack.toml"]
+  pre_package = "./scripts/build.sh"

constants.go

@@ -0,0 +1,8 @@
+package yarnstart
+
+const (
+	Node        = "node"
+	NodeModules = "node_modules"
+	Tini        = "tini"
+	Yarn        = "yarn"
+)

detect.go

@@ -0,0 +1,52 @@
+package yarnstart
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/paketo-buildpacks/packit"
+)
+
+func Detect() packit.DetectFunc {
+	return func(context packit.DetectContext) (packit.DetectResult, error) {
+		_, err := os.Stat(filepath.Join(context.WorkingDir, "yarn.lock"))
+		if err != nil {
+			if os.IsNotExist(err) {
+				return packit.DetectResult{}, packit.Fail
+			}
+			return packit.DetectResult{}, fmt.Errorf("failed to stat yarn.lock: %w", err)
+		}
+
+		return packit.DetectResult{
+			Plan: packit.BuildPlan{
+				Requires: []packit.BuildPlanRequirement{
+					{
+						Name: Node,
+						Metadata: map[string]interface{}{
+							"launch": true,
+						},
+					},
+					{
+						Name: NodeModules,
+						Metadata: map[string]interface{}{
+							"launch": true,
+						},
+					},
+					{
+						Name: Yarn,
+						Metadata: map[string]interface{}{
+							"launch": true,
+						},
+					},
+					{
+						Name: Tini,
+						Metadata: map[string]interface{}{
+							"launch": true,
+						},
+					},
+				},
+			},
+		}, nil
+	}
+}

detect_test.go

@@ -0,0 +1,103 @@
+package yarnstart_test
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/paketo-buildpacks/packit"
+	yarnstart "github.com/paketo-buildpacks/yarn-start"
+	"github.com/sclevine/spec"
+
+	. "github.com/onsi/gomega"
+)
+
+func testDetect(t *testing.T, context spec.G, it spec.S) {
+	var (
+		Expect = NewWithT(t).Expect
+
+		workingDir string
+		detect     packit.DetectFunc
+	)
+
+	it.Before(func() {
+		var err error
+		workingDir, err = ioutil.TempDir("", "working-dir")
+		Expect(err).NotTo(HaveOccurred())
+
+		detect = yarnstart.Detect()
+	})
+
+	it.After(func() {
+		Expect(os.RemoveAll(workingDir)).To(Succeed())
+	})
+
+	context("when there is a yarn.lock", func() {
+		it.Before(func() {
+			Expect(ioutil.WriteFile(filepath.Join(workingDir, "yarn.lock"), nil, 0644)).To(Succeed())
+		})
+		it("detects", func() {
+			result, err := detect(packit.DetectContext{
+				WorkingDir: workingDir,
+			})
+			Expect(err).NotTo(HaveOccurred())
+			Expect(result.Plan).To(Equal(packit.BuildPlan{
+				Requires: []packit.BuildPlanRequirement{
+					{
+						Name: "node",
+						Metadata: map[string]interface{}{
+							"launch": true,
+						},
+					},
+					{
+						Name: "node_modules",
+						Metadata: map[string]interface{}{
+							"launch": true,
+						},
+					},
+					{
+						Name: "yarn",
+						Metadata: map[string]interface{}{
+							"launch": true,
+						},
+					},
+					{
+						Name: "tini",
+						Metadata: map[string]interface{}{
+							"launch": true,
+						},
+					},
+				},
+			}))
+		})
+	})
+
+	context("when there is no yarn.lock", func() {
+		it("fails detection", func() {
+			_, err := detect(packit.DetectContext{
+				WorkingDir: workingDir,
+			})
+			Expect(err).To(MatchError(packit.Fail))
+		})
+	})
+
+	context("failure cases", func() {
+		context("the workspace directory cannot be accessed", func() {
+			it.Before(func() {
+				Expect(os.Chmod(workingDir, 0000)).To(Succeed())
+			})
+
+			it.After(func() {
+				Expect(os.Chmod(workingDir, os.ModePerm)).To(Succeed())
+			})
+
+			it("returns an error", func() {
+				_, err := detect(packit.DetectContext{
+					WorkingDir: workingDir,
+				})
+				Expect(err).To(MatchError(ContainSubstring("failed to stat yarn.lock:")))
+			})
+		})
+	})
+}

go.mod

@@ -0,0 +1,12 @@
+module github.com/paketo-buildpacks/yarn-start
+
+go 1.14
+
+require (
+	github.com/BurntSushi/toml v0.3.1
+	github.com/onsi/gomega v1.10.1
+	github.com/paketo-buildpacks/occam v0.0.17
+	github.com/paketo-buildpacks/packit v0.2.6
+	github.com/sclevine/spec v1.4.0
+	golang.org/x/net v0.0.0-20200707034311-ab3426394381 // indirect
+)