paired with @elbandito on multibuildpack support

bin/build

@@ -23,5 +23,11 @@ mkdir -p "${profile_dir}/profile.d"
 cp .profile.d/* "${profile_dir}/profile.d/"
 echo "launch = true" > ${layers_dir}/profile.toml
 
+if [ -f "{$target_dir}/exports" ]; then
+	echo "build = true" >> ${layers_dir}/profile.toml
+	mkdir -p "${profile_dir}/profile.d/env.build/"
+	"${bp_dir}/bin/exports" "${target_dir}/exports" "${platform_dir}"
+fi
+
 # run bin/release, read Procfile, and generate launch.toml
 "${bp_dir}/bin/release" "${target_dir}" "${layers_dir}" "${platform_dir}"

cmd/exports/main.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strings"
+
+	"github.com/buildpack/libbuildpack/logger"
+)
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Println("Usage:", os.Args[0], "EXPORTS_PATH", "PLATFORM_DIR")
+		return
+	}
+
+	log, err := logger.DefaultLogger(os.Args[3])
+	if err != nil {
+		log.Info(err.Error())
+		os.Exit(1)
+	}
+
+	exportsPath := os.Args[1]
+
+	data, err := ioutil.ReadFile(exportsPath)
+	if err != nil {
+		log.Info(err.Error())
+		os.Exit(2)
+	}
+
+	contents := string(data)
+	lines := strings.SplitN(contents, "\n", 2)
+
+	for _, line := range lines {
+		components := strings.Split(line, "=")
+		ioutil.WriteFile(components[0], []byte(components[1]), 0644)
+	}
+}