Fix release YAML pollution from runtime Go compilation

Fixes #1208 where deploying via git URL buildpack fails with:
'buildpack's release output invalid: yaml: line 4: mapping values
are not allowed in this context'

Root cause: bin/detect and bin/release wrapper scripts compiled Go
binaries at runtime, polluting stdout with build messages before
YAML output. Cloud Foundry expects pure YAML on stdout during the
release phase.

Solution follows the pattern from Java buildpack (commit 11e9bfc5):

- Convert bin/detect to pure bash (no runtime compilation)
- Simplify bin/release to just 'cat' pre-generated YAML file
- Generate release YAML in finalize phase (finalize.go)
- Remove obsolete src/php/detect and src/php/release Go CLIs
- Add regression test for git URL deployments

Changes:
- bin/detect: Pure bash detection logic (~40 lines)
- bin/release: Cat YAML file from tmp/php-buildpack-release-step.yml
- finalize.go: Write release YAML during finalize phase
- Deleted: src/php/detect/, src/php/release/ directories
- Added integration test for git URL buildpack deployment

Net result: -70 lines of code, clean YAML output, no pollution

Author: ramonskie

bin/detect

@@ -1,15 +1,37 @@
 #!/bin/bash
-set -euo pipefail
+# Cloud Foundry PHP Buildpack - Detect Script
+# Pure bash implementation matching Ruby/Java buildpack pattern
+
+set -e
 
 BUILD_DIR=$1
+BUILDPACK_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+VERSION=$(cat "$BUILDPACK_DIR/VERSION" 2>/dev/null || echo "unknown")
+
+# 1. Check for composer.json (most common indicator)
+[ -f "$BUILD_DIR/composer.json" ] && echo "php $VERSION" && exit 0
+
+# 2. Check for .php files
+compgen -G "$BUILD_DIR/*.php" > /dev/null 2>&1 && echo "php $VERSION" && exit 0
+
+# 3. Check for common web directories with PHP files
+for webdir in htdocs public web www; do
+  if [ -d "$BUILD_DIR/$webdir" ]; then
+    compgen -G "$BUILD_DIR/$webdir/*.php" > /dev/null 2>&1 && echo "php $VERSION" && exit 0
+  fi
+done
 
-export BUILDPACK_DIR=`dirname $(readlink -f ${BASH_SOURCE%/*})`
-source "$BUILDPACK_DIR/scripts/install_go.sh"
-output_dir=$(mktemp -d -t detectXXX)
+# 4. Check for index.php in subdirectories (common pattern)
+[ -f "$BUILD_DIR/htdocs/index.php" ] && echo "php $VERSION" && exit 0
+[ -f "$BUILD_DIR/public/index.php" ] && echo "php $VERSION" && exit 0
+[ -f "$BUILD_DIR/web/index.php" ] && echo "php $VERSION" && exit 0
+[ -f "$BUILD_DIR/www/index.php" ] && echo "php $VERSION" && exit 0
 
-pushd $BUILDPACK_DIR
-echo "-----> Running go build detect"
-GOROOT=$GoInstallDir $GoInstallDir/bin/go build -mod=vendor -o $output_dir/detect ./src/php/detect/cli
-popd
+# 5. Check for PHP files recursively (slower, last resort)
+if find "$BUILD_DIR" -maxdepth 3 -name "*.php" -type f 2>/dev/null | head -1 | grep -q .; then
+  echo "php $VERSION"
+  exit 0
+fi
 
-$output_dir/detect "$BUILD_DIR"
+# Not a PHP app
+exit 1

bin/release

@@ -2,14 +2,4 @@
 set -euo pipefail
 
 BUILD_DIR=$1
-
-export BUILDPACK_DIR=`dirname $(readlink -f ${BASH_SOURCE%/*})`
-source "$BUILDPACK_DIR/scripts/install_go.sh"
-output_dir=$(mktemp -d -t releaseXXX)
-
-pushd $BUILDPACK_DIR
-echo "-----> Running go build release"
-GOROOT=$GoInstallDir $GoInstallDir/bin/go build -mod=vendor -o $output_dir/release ./src/php/release/cli
-popd
-
-$output_dir/release "$BUILD_DIR"
+cat $BUILD_DIR/tmp/php-buildpack-release-step.yml

src/php/detect/cli/main.go

@@ -138,6 +138,21 @@ func Run(f *Finalizer) error {
 		return err
 	}
 
+	// Write release YAML file for bin/release to consume
+	tmpDir := filepath.Join(f.Stager.BuildDir(), "tmp")
+	if err := os.MkdirAll(tmpDir, 0755); err != nil {
+		return fmt.Errorf("failed to create tmp directory: %w", err)
+	}
+
+	releaseYamlPath := filepath.Join(tmpDir, "php-buildpack-release-step.yml")
+	yamlContent := `---
+default_process_types:
+  web: $HOME/.bp/bin/start
+`
+	if err := os.WriteFile(releaseYamlPath, []byte(yamlContent), 0644); err != nil {
+		return fmt.Errorf("failed to write release YAML: %w", err)
+	}
+
 	f.Log.Info("PHP buildpack finalize phase complete")
 	return nil
 }

src/php/detect/detect.go

@@ -91,5 +91,31 @@ func testDefault(platform switchblade.Platform, fixtures string) func(*testing.T
 			})
 		})
 
+		context("PHP app deployed via git URL buildpack", func() {
+			it("successfully builds without release YAML pollution", func() {
+				if settings.Platform == "docker" {
+					t.Skip("Git URL buildpacks require CF platform - Docker platform cannot clone git repos")
+				}
+
+				deployment, logs, err := platform.Deploy.
+					WithBuildpacks("https://github.com/cloudfoundry/php-buildpack.git").
+					WithEnv(map[string]string{
+						"BP_DEBUG": "1",
+					}).
+					Execute(name, filepath.Join(fixtures, "default"))
+
+				Expect(err).NotTo(HaveOccurred(), logs.String)
+
+				Eventually(logs).Should(SatisfyAll(
+					ContainLines("Installing PHP"),
+					ContainLines(MatchRegexp(`PHP [\d\.]+`)),
+				))
+
+				Eventually(deployment).Should(Serve(
+					ContainSubstring("PHP Version"),
+				))
+			})
+		})
+
 	}
 }