Add support for idiomatic SvelteKit applications

This commit bolsters our node.js entry point logic to detect SvelteKit applications.

Fixes #381

PiperOrigin-RevId: 617978159
Change-Id: I00cff183205228969add445eba491bc03b020266

Author: matthewrobertson

cmd/nodejs/npm/main.go

@@ -144,8 +144,12 @@ func buildFn(ctx *gcp.Context) error {
 		// If there are multiple build scripts to run, run them one-by-one so the logs are
 		// easier to understand.
 		for _, cmd := range buildCmds {
+			execOpts := []gcp.ExecOption{gcp.WithUserAttribution}
+			if nodejs.DetectSvelteKitAutoAdapter(pjs) {
+				execOpts = append(execOpts, gcp.WithEnv(nodejs.SvelteAdapterEnv))
+			}
 			split := strings.Split(cmd, " ")
-			if _, err := ctx.Exec(split, gcp.WithUserAttribution); err != nil {
+			if _, err := ctx.Exec(split, execOpts...); err != nil {
 				if !isCustomBuild {
 					return fmt.Errorf(`%w
 NOTE: Running the default build script can be skipped by passing the empty environment variable "%s=" to the build`, err, nodejs.GoogleNodeRunScriptsEnv)

pkg/nodejs/BUILD.bazel

@@ -12,6 +12,7 @@ go_library(
         "nuxt.go",
         "pnpm.go",
         "registry.go",
+        "sveltekit.go",
         "yarn.go",
     ],
     importpath = "github.com/GoogleCloudPlatform/buildpacks/" + package_name(),
@@ -44,6 +45,7 @@ go_test(
         "nuxt_test.go",
         "pnpm_test.go",
         "registry_test.go",
+        "sveltekit_test.go",
         "yarn_test.go",
     ],
     data = glob(["testdata/**"]),

pkg/nodejs/npm.go

@@ -218,6 +218,9 @@ func DefaultStartCommand(ctx *gcp.Context, pjs *PackageJSON) ([]string, error) {
 	if nuxt, err := NuxtStartCommand(ctx); err != nil || nuxt != nil {
 		return nuxt, err
 	}
+	if svelteKit, err := SvelteKitStartCommand(ctx); err != nil || svelteKit != nil {
+		return svelteKit, err
+	}
 	exists, err := ctx.FileExists(ctx.ApplicationRoot(), "server.js")
 	if err != nil {
 		return nil, err

pkg/nodejs/nuxt_test.go

@@ -54,7 +54,7 @@ func TestNuxtStartCommand(t *testing.T) {
 				}
 				_, err := safeopen.CreateBeneath(dir, "index.mjs")
 				if err != nil {
-					t.Fatalf("failed to create server.js: %v", err)
+					t.Fatalf("failed to create index.mjs: %v", err)
 				}
 			}
 			ctx := gcpbuildpack.NewContext(gcpbuildpack.WithApplicationRoot(home))

pkg/nodejs/sveltekit.go

@@ -0,0 +1,43 @@
+package nodejs
+
+import (
+	"strings"
+
+	gcp "github.com/GoogleCloudPlatform/buildpacks/pkg/gcpbuildpack"
+)
+
+// SvelteAdapterEnv is an env var that enables SvelteKit to detect
+// Google Cloud Buildpacks and use adapter-node when adapter-auto is detected
+// https://github.com/sveltejs/kit/blob/main/packages/adapter-auto/adapters.js
+const SvelteAdapterEnv = "GCP_BUILDPACKS=TRUE"
+
+// DetectSvelteKitAutoAdapter returns true if the given package.json file
+// contains the @sveltejs/adapter-auto dependency and no others.
+func DetectSvelteKitAutoAdapter(p *PackageJSON) bool {
+	// Check and reject if the package contains an adapter that is
+	// not the @sveltejs/adapter-auto dependency.
+	for k := range p.DevDependencies {
+		if strings.HasPrefix(k, "@sveltejs/adapter-") && k != "@sveltejs/adapter-auto" {
+			return false
+		}
+	}
+	_, ok := p.DevDependencies["@sveltejs/adapter-auto"]
+	return ok
+}
+
+// SvelteKitStartCommand determines if this is a SvelteKit application and returns the command to start the
+// SvelteKit server. If not it is not a SvelteKit application it returns nil.
+func SvelteKitStartCommand(ctx *gcp.Context) ([]string, error) {
+	configExists, err := ctx.FileExists(ctx.ApplicationRoot(), "svelte.config.js")
+	if err != nil {
+		return nil, err
+	}
+	serverExists, err := ctx.FileExists(ctx.ApplicationRoot(), "build/index.js")
+	if err != nil {
+		return nil, err
+	}
+	if configExists && serverExists {
+		return []string{"node", "build/index.js"}, nil
+	}
+	return nil, nil
+}

pkg/nodejs/sveltekit_test.go

@@ -0,0 +1,132 @@
+package nodejs
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"google3/security/safeopen/safeopen"
+	"github.com/GoogleCloudPlatform/buildpacks/pkg/gcpbuildpack"
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestSvelteKitStartCommand(t *testing.T) {
+	testsCases := []struct {
+		name         string
+		configExists bool
+		buildExists  bool
+		want         []string
+	}{
+		{
+			name: "no config or build",
+			want: nil,
+		},
+		{
+			name:        "no config",
+			buildExists: true,
+			want:        nil,
+		},
+		{
+			name:         "no build",
+			configExists: true,
+			want:         nil,
+		},
+		{
+			name:         "sveltekit app",
+			buildExists:  true,
+			configExists: true,
+			want:         []string{"node", "build/index.js"},
+		},
+	}
+	for _, tc := range testsCases {
+		t.Run(tc.name, func(t *testing.T) {
+			home := t.TempDir()
+			if tc.configExists {
+				_, err := safeopen.CreateBeneath(home, "svelte.config.js")
+				if err != nil {
+					t.Fatalf("failed to create server.js: %v", err)
+				}
+			}
+			if tc.buildExists {
+				dir := filepath.Join(home, "build")
+				if err := os.MkdirAll(dir, 0755); err != nil {
+					t.Fatalf("failed to create build directory: %v", err)
+				}
+				_, err := safeopen.CreateBeneath(dir, "index.js")
+				if err != nil {
+					t.Fatalf("failed to create index.js: %v", err)
+				}
+			}
+			ctx := gcpbuildpack.NewContext(gcpbuildpack.WithApplicationRoot(home))
+
+			got, err := SvelteKitStartCommand(ctx)
+			if err != nil {
+				t.Fatalf("SvelteKitStartCommand() got error: %v", err)
+			}
+			if diff := cmp.Diff(tc.want, got); diff != "" {
+				t.Errorf("SvelteKitStartCommand() mismatch (-want +got):\n%s", diff)
+			}
+		})
+	}
+}
+
+func TestDetectSvelteKitAutoAdapter(t *testing.T) {
+	testsCases := []struct {
+		name string
+		pjs  string
+		want bool
+	}{
+		{
+			name: "with sveltekit auto adapter",
+			pjs: `{
+					"devDependencies": {
+						"@sveltejs/adapter-auto": "^3.0.0"
+					}
+				}`,
+			want: true,
+		},
+		{
+			name: "with two sveltekit adapters",
+			pjs: `{
+					"devDependencies": {
+						"@sveltejs/adapter-auto": "^3.0.0",
+						"@sveltejs/adapter-node": "^5.0.1"
+					}
+				}`,
+			want: false,
+		},
+		{
+			name: "with no sveltekit adapters",
+			pjs: `{
+        "scripts": {
+					"dev": "vite dev",
+					"build": "vite build",
+					"preview": "vite preview",
+					"check": "svelte-kit sync && svelte-check --tsconfig ./jsconfig.json",
+					"check:watch": "svelte-kit sync && svelte-check --tsconfig ./jsconfig.json --watch"
+				}
+			}`,
+			want: false,
+		},
+		{
+			name: "no scripts",
+			pjs:  `{}`,
+			want: false,
+		},
+	}
+	for _, tc := range testsCases {
+		t.Run(tc.name, func(t *testing.T) {
+			var pjs *PackageJSON = nil
+			if tc.pjs != "" {
+				if err := json.Unmarshal([]byte(tc.pjs), &pjs); err != nil {
+					t.Fatalf("failed to unmarshal package.json: %s, error: %v", tc.pjs, err)
+				}
+			}
+
+			if got := DetectSvelteKitAutoAdapter(pjs); got != tc.want {
+				t.Errorf("DetectSvelteKitAutoAdapter() = %v, want %v", got, tc.want)
+			}
+		})
+	}
+}